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Background: Damage from insect herbivores can elicit a wide range of plant responses, including reduced or compensatory growth, altered volatile profiles, or increased production of defence compounds. Specifically, herbivory can alter floral development as plants reallocate resources towards defence and regrowth functions. For pollinator-dependent species, floral quantity and quality are critical for attracting floral visitors; thus, herbivore-induced developmental effects that alter either floral abundance or attractiveness may have critical implications for plant reproductive success. Based on past work on resource trade-offs, we hypothesize that herbivore damage-induced effects are stronger in structural floral traits that require significant resource investment (e.g. flower quantity), as plants reallocate resources towards defence and regrowth, and weaker in secondary floral traits that require less structural investment (e.g. nectar rewards)., Methods: In this study, we simulated early-season herbivore mechanical damage in the domesticated jack-o-lantern pumpkin Cucurbita pepo ssp. pepo and measured a diverse suite of floral traits over a 60-d greenhouse experiment., Key Results: We found that mechanical damage delayed the onset of male anthesis and reduced the total quantity of flowers produced. Additionally, permutational multivariate analysis of variance (PERMANOVA) indicated that mechanical damage significantly impacts overall floral volatile profile, though not output of sesquiterpenoids, a class of compounds known to recruit specialized cucumber beetle herbivores and squash bee pollinators., Conclusions: We show that C. pepo spp. pepo reduces investment in male flower production following mechanical damage, and that floral volatiles do exhibit shifts in production, indicative of damage-induced trait plasticity. Such reductions in male flower production could reduce the relative attractiveness of damaged plants to foraging pollinators in this globally relevant cultivated species., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The globally changing climatic condition is increasing the incidences of drought in several parts of the world. This is predicted and already shown to not only impact plant growth and flower development, but also plant-pollinator interactions and the pollination success of entomophilous plants. However, there is a large gap in our understanding of how drought affects the different flowers and pollen transfer among flowers in sexually polymorphic species. Here, we evaluated in monoecious Styrian oil pumpkin, and separately for female and male flowers, the responses of drought stress on flower production, petal size, nectar, floral scent and visitation by bumblebee pollinators. Drought stress adversely affected all floral traits studied, except floral scent. Although both flower sexes were adversely affected by drought stress, the effects were more severe on female flowers, with most of the female flowers even aborted before opening. The drought had negative effects on floral visitation by the pollinators, which generally preferred female flowers. Overall, our study highlights that the two flower sexes of a monoecious plant species are differently affected by drought stress and calls for further investigations to better understand the cues used by the pollinators to discriminate against male flowers and against flowers of drought-stressed plants., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)

Key Message: Two major QTLs for cold tolerance in pumpkin were localised, and CmoERF017 was identified as a key candidate gene within these QTLs via RNA-seq. Functional analysis revealed that CmoERF017 was a positive regulator of pumpkin in response to low-temperature stress. Low temperature is a key environmental factor that affects the protected cultivation of cucumber (Cucumis sativus L.) in winter, and the cold tolerance of cucumber/pumpkin-grafted seedlings depends on the rootstock. Pumpkin (Cucurbita spp.) has a well-developed root system, high resistance and wide adaptation, commonly used as rootstock for cucumber to improve the cold tolerance of grafted seedlings. This study used two high-generation inbred lines of Cucurbita moschata with significant differences in cold tolerance. We identified key candidate genes within the major cold tolerance QTL of rootstocks using QTL-seq and RNA-seq and investigated the function and molecular mechanisms of these genes in response to low-temperature stress. Results showed that QTL-seq located two cold tolerance QTLs, qCII-1 and qCII-2, while RNA-seq located 28 differentially expressed genes within these QTLs. CmoERF017 was finally identified as a key candidate gene. Functional validation results indicated that CmoERF017 is a positive regulator of pumpkin in response to low-temperature stress and affected root ABA synthesis and signalling by directly regulating the expression of SDR7 and ABI5. This study identified a key gene for low-temperature stress tolerance in rootstock pumpkin and clarified its role in the molecular mechanism of hormone-mediated plant cold tolerance. The study findings enrich the theoretical understanding of low-temperature stress tolerance in pumpkin and are valuable for the selection and breeding of cold-tolerant varieties of pumpkin used for rootstocks., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Key Message: We identified a 580 bp deletion of CmaKNAT6 coding region influences peel colour of mature Cucurbita maxima fruit. Peel colour is an important agronomic characteristic affecting commodity quality in Cucurbit plants. Genetic mapping of fruit peel colour promotes molecular breeding and provides an important basis for understanding the regulatory mechanism in Cucurbit plants. In the present study, the Cucurbita maxima inbred line '9-6' which has a grey peel colour and 'U3-3-44' which has a dark green peel colour in the mature fruit stage, were used as plant materials. At 5-40 days after pollination (DAP), the contents of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids in the 'U3-3-44' peels were significantly greater than those in the '9-6' peels. In the epicarp of the '9-6' mature fruit, the presence of nonpigmented cell layers and few chloroplasts in each cell in the pigmented layers were observed. Six generations derived by crossing '9-6' and 'U3-3-44' were constructed, and the dark green peel was found to be controlled by a single dominant locus, which was named CmaMg (mature green peel). Through bulked-segregant analysis sequencing (BSA-seq) and insertion-deletion (InDel) markers, CmaMg was mapped to a region of approximately 449.51 kb on chromosome 11 using 177 F 2 individuals. Additionally, 1703 F 2 plants were used for fine mapping to compress the candidate interval to a region of 32.34 kb. Five coding genes were in this region, and CmaCh11G000900 was identified as a promising candidate gene according to the reported function, sequence alignment, and expression analyses. CmaCh11G000900 (CmaKNAT6) encodes the homeobox protein knotted-1-like 6 and contains 4 conserved domains. CmaKNAT6 of '9-6' had a 580 bp deletion, leading to premature transcriptional termination. The expression of CmaKNAT6 tended to increase sharply during the early fruit development stage but decrease gradually during the late period of fruit development. Allelic diversity analysis of pumpkin germplasm resources indicated that the 580 bp deletion in the of CmaKNAT6 coding region was associated with peel colour. Subcellular localization analysis indicated that CmaKNAT6 is a nuclear protein. Transcriptomic analysis of the inbred lines '9-6' and 'U3-3-44' indicated that genes involved in chlorophyll biosynthesis were more enriched in 'U3-3-44' than in '9-6'. Additionally, the expression of transcription factor genes that positively regulate chlorophyll synthesis and light signal transduction pathways was upregulated in 'U3-3-44'. These results lay a foundation for further studies on the genetic mechanism underlying peel colour and for optimizing peel colour-based breeding strategies for C. maxima., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Jasmonates are growth regulators that play a key role in flower development, fruit ripening, root growth, and plant defence. The study explores the coordination of floral organ maturation to ensure proper flower opening for pollination and fertilization. A new mutant (jar1b) was discovered, lacking petal elongation and flower opening but showing normal pistil and stamen development, leading to parthenocarpic fruit development. The mutation also enhanced the elongation of roots while reducing the formation of root hairs. BSA sequencing showed that jar1b is a missense mutation in the gene CpJAR1B, which encodes the enzyme that catalyzes the conjugation between JA and the amino acid isoleucine. The loss of function mutation in CpJAR1B produced a deficiency in biologically active (+) -7-iso-jasmonoyl-L-isoleucine (JA-Ile), which was not complemented by the paralogous gene CpJAR1A or any other redundant gene. Exogenous application of methyl jasmonate (MeJA) demonstrated that jar1b is partially insensitive to JA in both flowers and roots. Further experimentation involving the combination of JA-Ile deficient and ethylene-deficient, and ET insensitive mutations in double mutants revealed that CpJAR1B mediated ET action in female petal maturation and flower opening, but JA and ET have independent additive effects as negative regulators of the set and development of squash fruits. CpJAR1B also regulated the aperture of male flowers in an ethylene-independent manner. The root phenotype of jar1b and effects of external MeJA treatments indicated that CpJAR1B has a dual role in root development, inhibiting the elongation of primary and secondary roots, but promoting the formation of root hairs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

The emerging wearable plant sensors demonstrate the capability of in-situ measurement of physiological and micro-environmental information of plants. However, the stretchability and breathability of current wearable plant sensors are restricted mainly due to their 2D planar structures, which interfere with plant growth and development. Here, origami-inspired 3D wearable sensors have been developed for plant growth and microclimate monitoring. Unlike 2D counterparts, the 3D sensors demonstrate theoretically infinitely high stretchability and breathability derived from the structure rather than the material. They are adjusted to 100% and 111.55 mg cm -2 ·h -1 in the optimized design. In addition to stretchability and breathability, the structural parameters are also used to control the strain distribution of the 3D sensors to enhance sensitivity and minimize interference. After integrating with corresponding sensing materials, electrodes, data acquisition and transmission circuits, and a mobile App, a miniaturized sensing system is produced with the capability of in-situ and online monitoring of plant elongation and microclimate. As a demonstration, the 3D sensors are worn on pumpkin leaves, which can accurately monitor the leaf elongation and microclimate with negligible hindrance to plant growth. Finally, the effects of the microclimate on the plant growth is resolved by analyzing the monitored data. This study would significantly promote the development of wearable plant sensors and their applications in the fields of plant phenomics, plant-environment interface, and smart agriculture., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Melatonin regulates defense responses in plants under environmental stress. This study aimed to explore the impact of exogenous melatonin on the phenotype and physiology of 'BM1' pumpkin seedlings subjected to waterlogging stress. Waterlogging stress was induced following foliar spraying of melatonin at various concentrations (CK, 0, 10, 100, 200, and 300 μmol·L -1 ). The growth parameters, malondialdehyde (MDA) content, antioxidant enzyme activity, osmoregulatory substance levels, and other physiological indicators were assessed to elucidate the physiological mechanisms underlying the role of exogenous melatonin in mitigating waterlogging stress in pumpkin seedlings. The results indicate that pumpkin seedlings exhibit waterlogging symptoms, such as leaf wilting, water loss, edge chlorosis, and fading, under waterlogging stress conditions. Various growth indicators of the seedlings, including plant height, stem diameter, root length, fresh and dry weight, and leaf chlorophyll content, were significantly reduced. Moreover, the MDA content in leaves and roots increased significantly, along with elevated activities of superoxide dismutase, catalase, peroxidase, and soluble protein contents. When different concentrations of melatonin were sprayed on the leaves post waterlogging stress treatment, pumpkin seedlings showed varying degrees of recovery, with the 100 μmol·L -1 treatment displaying the best growth status and plant morphological phenotypes. There were no significant differences compared to the control group. Seedling growth indicators, chlorophyll content, root activity, antioxidant enzyme activities, soluble protein content, and osmotic adjustment substance content all increased to varying degrees with increasing melatonin concentration, peaking at 100 μmol·L -1 . Melatonin also reduced membrane damage caused by oxidative stress and alleviated osmotic imbalance. Exogenous melatonin enhanced the activities of antioxidant enzymes and systems involved in scavenging reactive oxygen species, with 100 μmol·L -1 as the optimal concentration. These findings underscore the crucial role of exogenous melatonin in alleviating waterlogging stress in pumpkins. The findings of this study offer a theoretical framework and technical assistance for cultivating waterlogging-resistant pumpkins in practical settings. Additionally, it establishes a theoretical groundwork for the molecular breeding of pumpkins with increased tolerance to waterlogging., Competing Interests: The authors declare that they have no competing interests., (© 2024 Liu et al.)

Cucurbita moschata varieties grown in Africa have very low yield. They have been neglected, and totally ignored in agricultural research programs. However, interest in their fruits, seeds, flowers and leaves is growing nowadays due to their nutritional and medicinal potentials. That growing interest has prompted plant breeders and agronomists to develop research programs for their improvement. A complete diallel cross analysis of four parental lines, Long, Zouan-H, Oval, and Soubre and their twelve F1 hybrids, was carried out in a farming environment at the University Nangui Abrogoua, Abidjan, Côte d'Ivoire. The four parental lines and the F1 hybrids were evaluated for their general performances, combining abilities, potency ratio and heterosis effects. The investigated traits included plant height, and eleven fruit- and seed-related characters. The analysis of variance showed significant differences for all traits studied. In addition, the diallel model yielded highly significant gca effects of the female parents. The gca effects of the male parents were significant for all traits except plant height, length of the fruit, width of the fruit and length of the seed. Highly significant sca effects were observed in the crosses for all the traits. Strong maternal effects were observed for the weight and diameter of the fruit, weight of the pulp, number of seeds per fruit, weight of the fresh seeds and 100-seed weight. The general predictive ratio approached the value 1 for all the traits except weight of the fresh seed and width of the dry seed. Most of the characters under this study are predominantly determined by the effects of additive genes. But, weight of the fresh seed and width of the dry seed may be controlled by non-additive genes. Mid-parent heterosis was significant for all measured traits in the crosses, except the length of the fruit. And better-parent heterosis was significant for all traits except plant height, number of fruits per plant and length of the fruit. Gene expression is described by a super-dominance for many traits, and partial dominance for some other traits in all twelve F1 hybrids. Classification of the parental lines based on the effects of their general combining ability grouped the Soubre lines as promising contributors to fruit yield. The parental lines Long and Oval formed another group likely on the basis of the small size of their fruits, the small pulps, the smaller number of fruits per plant and the large number of seeds per fruit. However, Long would be a candidate parent for the development of cultivars with longer vegetative growth. The parental line Zouan-H formed the third group and it was mostly characterized by its large number of seeds per fruit and relatively large fruits., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 KOUAGO et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The crosstalk of phytohormones in the regulation of growth and development and the response of plants to environmental stresses is a cutting-edge research topic, especially in crop species. In this paper, we study the role and crosstalk between abscisic acid (ABA), ethylene (ET), and jasmonate (JA) in the control of germination and seedling growth in water or in standard nutrient solution and under salt stress (supplemented with 100-200 mM NaCl). The roles of ET and JA were studied using squash ET- and JA-deficient mutants aco1a and lox3a , respectively, while the crosstalk between ET, JA, and ABA was determined by comparing the expression of the key ABA, JA, and ET genes in wild-type (WT) and mutant genotypes under standard conditions and salt stress. Data showed that ET and JA are positive regulators of squash germination, a function that was found to be mediated by downregulating the ABA biosynthesis and signaling pathways. Under salt stress, aco1a germinated earlier than WT, while lox3a showed the same germination rate as WT, indicating that ET, but not JA, restricts squash germination under unfavorable salinity conditions, a function that was also mediated by upregulation of ABA. ET and JA were found to be negative regulators of plant growth during seedling establishment, although ET inhibits both the aerial part and the root, while JA inhibits only the root. Both aco1a and lox3a mutant roots showed increased tolerance to salt stress, a phenotype that was found to be mainly mediated by JA, although we cannot exclude that it is also mediated by ABA.

Key Message: A large fragment deletion of CpAPRR2, encoding a two-component response regulator-like protein, which influences immature white rind color formation in zucchini (Cucurbita pepo). Fruit rind color is an important agronomic trait that affects commodity quality and consumer choice in zucchini (Cucurbita pepo). However, the molecular mechanism controlling rind color is unclear. We characterized two zucchini inbred lines: '19' (dark green rind) and '113' (white rind). Genetic analysis revealed white immature fruit rind color to be controlled by a dominant locus (CpW). Combining bulked segregant analysis sequencing (BSA-seq) and Kompetitive Allele-Specific PCR (KASP) markers, we mapped the CpW locus to a 100.4 kb region on chromosome 5 and then narrow down the candidate region to 37.5 kb using linkage analysis of 532 BC 1 and 1613 F 2 individuals, including 6 coding genes. Among them, Cp4.1LG05g02070 (CpAPRR2), encoding a two-component response regulator-like protein, was regarded to be a promising candidate gene. The expression level of CpAPRR2 in dark green rind was significantly higher than that in white rind and was induced by light. A deletion of 2227 bp at the 5' end of CpAPRR2 in '113' might explain the white phenotype. Further analysis of allelic diversity in zucchini germplasm resources revealed rind color to be associated with the deletion of CpAPRR2. Subcellular localization analysis indicated that CpAPRR2 was a nuclear protein. Transcriptome analysis using near-isogenic lines with dark green (DG) and white (W) rind indicated that genes involved in photosynthesis and porphyrin metabolism pathways were enriched in DG compared with W. Additionally, chlorophyll synthesis-related genes were upregulated in DG. These results identify mechanisms of zucchini rind color and provide genetic resources for breeding., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Long noncoding RNAs (lncRNAs) play important roles in various biological processes. However, the regulatory roles of lncRNAs underlying fruit development have not been extensively studied. The pumpkin (Cucurbita spp.) is a preferred model for understanding the molecular mechanisms regulating fruit development because of its variable shape and size and large inferior ovary. Here, we performed strand-specific transcriptome sequencing on pumpkin (Cucurbita maxima "Rimu") fruits at 6 developmental stages and identified 5,425 reliably expressed lncRNAs. Among the 332 lncRNAs that were differentially expressed during fruit development, the lncRNA MSTRG.44863.1 was identified as a negative regulator of pumpkin fruit development. MSTRG.44863.1 showed a relatively high expression level and an obvious period-specific expression pattern. Transient overexpression and silencing of MSTRG.44863.1 significantly increased and decreased the content of 1-aminocyclopropane carboxylic acid (a precursor of ethylene) and ethylene production, respectively. RNA pull-down and microscale thermophoresis assays further revealed that MSTRG.44863.1 can interact with S-adenosyl-L-methionine synthetase (SAMS), an enzyme in the ethylene synthesis pathway. Considering that ethylene negatively regulates fruit development, these results indicate that MSTRG.44863.1 plays an important role in the regulation of pumpkin fruit development, possibly through interacting with SAMS and affecting ethylene synthesis. Overall, our findings provide a rich resource for further study of fruit-related lncRNAs while offering insights into the regulation of fruit development in plants., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists.)

A number of cis-regulatory elements (CREs) conserved during evolution have been found to be responsible for phenotypic novelty and variation. Cucurbit crops such as cucumber (Cucumis sativus), watermelon (Citrullus lanatus), melon (Cucumis melo), and squash (Cucurbita maxima) develop fruits from an inferior ovary and share some similar biological processes during fruit development. Whether conserved regulatory sequences play critical roles in fruit development of cucurbit crops remains to be explored. In six well-studied cucurbit species, we identified 392,438 conserved noncoding sequences (CNSs), including 82,756 that are specific to cucurbits, by comparative genomics. Genome-wide profiling of accessible chromatin regions (ACRs) and gene expression patterns mapped 20,865 to 43,204 ACRs and their potential target genes for two fruit tissues at two key developmental stages in six cucurbits. Integrated analysis of CNSs and ACRs revealed 4,431 syntenic orthologous CNSs, including 1,687 cucurbit-specific CNSs that overlap with ACRs that are present in all six cucurbit crops and that may regulate the expression of 757 adjacent orthologous genes. CRISPR mutations targeting two CNSs present in the 1,687 cucurbit-specific sequences resulted in substantially altered fruit shape and gene expression patterns of adjacent NAC1 (NAM, ATAF1/2, and CUC2) and EXT-like (EXTENSIN-like) genes, validating the regulatory roles of these CNSs in fruit development. These results not only provide a number of target CREs for cucurbit crop improvement, but also provide insight into the roles of CREs in plant biology and during evolution., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The WRKY gene family is crucial for regulating plant growth and development. However, the WRKY gene is rarely studied in naked kernel formation in hull-less Cucurbita pepo L. (HLCP), a natural mutant that lacks the seed coat. In this research, 76 WRKY genes were identified through bioinformatics-based methods in C. pepo , and their phylogenetics, conserved motifs, synteny, collinearity, and temporal expression during seed coat development were analyzed. The results showed that 76 CpWRKYs were identified and categorized into three main groups (I-III), with Group II further divided into five subgroups (IIa-IIe). Moreover, 31 segmental duplication events were identified in 49 CpWRKY genes. A synteny analysis revealed that C. pepo shared more collinear regions with cucumber than with melon. Furthermore, quantitative RT-PCR (qRT-PCR) results indicated the differential expression of CpWRKYs across different varieties, with notable variations in seed coat development between HLCP and CP being attributed to differences in CpWRKY5 expression. To investigate this further, CpWRKY5 -overexpression tobacco plants were generated, resulting in increased lignin content and an upregulation of related genes, as confirmed by qRT-PCR. This study offers valuable insights for future functional investigations of CpWRKY genes and presents novel information for understanding the regulation mechanism of lignin synthesis.

To increase agriculture production, accurate and fast detection of plant disease is required. Expert advice is needed to detect disease in plants, nutrition deficiencies or any other abnormalities caused by extreme weather conditions. But this process is very tedious, costly, and takes more time. In this paper, hyperspectral imaging and machine learning were used to detect different stages (early, middle, and critical stage) of the powderly mildew disease (PMD) in squash plants. An unmanned aerial vehicle (UAV) was used to collect the data from the field and Locality Preserving Discriminative Broad Learning (LPDBL) was used to distinguish the diseased and healthy plants. In addition, the ability to detect the diseased plant by the proposed method was evaluated using 10 different spectral vegetation indices (VIs). The results show the proposed method detected the disease accurately in the early, middle, and critical stages of the squash plant. The proposed method's performance is compared with six different PMDs under indoor laboratory test and UAV-based field test conditions. The comparison's results show that the LPDBL provides better accuracy in detecting disease in the squash plant.

Key Message: Powdery mildew resistance in zucchini is controlled by one major dominant locus, CpPM10.1. CpPM10.1 was fine mapped. The expression of candidate gene Cp4.1LG10g02780 in resistant individuals was significantly upregulated after inoculation with the powdery mildew. Powdery mildew (PM) is one of the most destructive fungal diseases, reducing the productivity of Cucurbita crops globally. PM influences the photosynthesis, growth and development of infected zucchini and seriously reduces fruit yield and quality. In the present study, the zucchini inbred line 'X10' had highly stable PM resistance, and the inbred line 'Jin234' was highly susceptible to PM in the seedling stage and adult stages. Genetic analysis revealed that PM resistance in 'X10' is controlled by one major dominant locus. Based on the strategy of QTL-seq combined with linkage analysis and developed molecular markers, the major locus was found to be located in a 382.9-kb candidate region on chromosome 10; therefore, the major locus was named CpPM10.1. Using 1,400 F 2 individuals derived from a cross between 'X10' and 'JIN234' and F 2:3 offspring of the recombinants, the CpPM10.1 locus was defined in a region of approximately 20.9 kb that contained 5 coding genes. Among them, Cp4.1LG10g02780 contained a conserved domain (RPW8), which controls resistance to a broad range of PM pathogens. Cp4.1LG10g02780 also had nonsynonymous SNPs between the resistant 'X10' and susceptible 'Jin234.' Furthermore, the expression of Cp4.1LG10g02780 was strongly positively involved in PM resistance in the key period of inoculation. Further allelic diversity analysis in zucchini germplasm resources indicated that PM resistance was associated with two SNPs in the Cp4.1LG10g02780 RPW8 domain. This study not only provides highly stable PM resistance gene resources for cucurbit crops but also lays the foundation for the functional analysis of PM resistance and resistance breeding in zucchini., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The finely tuned balance between sources and sinks determines plant resource partitioning and regulates growth and development. Understanding and measuring metabolic indicators of source or sink limitation forms a vital part of global efforts to increase crop yield for future food security. We measured metabolic profiles of Cucurbita pepo (zucchini) grown in the field under carbon sink limitation and control conditions. We demonstrate that these profiles can be measured non-destructively using hyperspectral reflectance at both leaf and canopy scales. Total non-structural carbohydrates (TNC) increased 82% in sink-limited plants; leaf mass per unit area (LMA) increased 38% and free amino acids increased 22%. Partial least-squares regression (PLSR) models link these measured functional traits with reflectance data, enabling high-throughput estimation of traits comprising the sink limitation response. Leaf- and canopy-scale models for TNC had R 2 values of 0.93 and 0.64 and %RMSE of 13 and 38%, respectively. For LMA, R 2 values were 0.91 and 0.60 and %RMSE 7 and 14%; for free amino acids, R 2 was 0.53 and 0.21 with %RMSE 20 and 26%. Remote sensing can enable accurate, rapid detection of sink limitation in the field at the leaf and canopy scale, greatly expanding our ability to understand and measure metabolic responses to stress., (Published 2021. This article is a U.S. Government work and is in the public domain in the USA.)

Climate change is a pressing matter of anthropogenic nature to which agriculture contributes by abusing production inputs such as inorganic fertilizers and fertigation water, thus degrading land and water sources. Moreover, as the increase in the demand of food in 2050 is estimated to be 25 to 70% more than what is currently produced today, a sustainable intensification of agriculture is needed. Biostimulant substances are products that the EU states work by promoting growth, resistance to plant abiotic stress, and increasing produce quality, and may be a valid strategy to enhance sustainable agricultural practice. Presented in this review is a comprehensive look at the scientific literature regarding the widely used and EU-sanctioned biostimulant substances categories of silicon, seaweed extracts, protein hydrolysates, and humic substances. Starting from their origin, the modulation of plants' hormonal networks, physiology, and stress defense systems, their in vivo effects are discussed on some of the most prominent vegetable species of the popular plant groupings of cucurbits, leafy greens, and nightshades. The review concludes by identifying several research areas relevant to biostimulant substances to exploit and enhance the biostimulant action of these substances and signaling molecules in horticulture.

During the growing season of 2018, several field-grown cucurbit plants in different parts of Iraq and Iran were surveyed for the presence of zucchini yellow mosaic virus (ZYMV), using two degenerate primer pairs (CIF/Rev and NIb2F/3R) targeting the two separated partial regions of the potyvirus genome (CI and NIb respectively). 7 out of 20 samples were confirmed to be infected with ZYMV. Phylogenetic analyses based on the CI gene grouped all Iranian and two Iraqi (ZYMV1 and ZYMV2) isolates together with isolates from the Middle East in the subgroup (AI), whereas the other Iraqi (ZYMV3 and ZYMV4) isolates were clustered in the subgroup (DI), which was only consisted of American isolates. The highest and lowest identity between the studied isolates and the GenBank isolates showed that the two genes (CI, NIb) of each isolate particularly the Iraqi isolates were more similar to a specific and geographically scattered mosaic of worldwide isolates, suggestive of mixed infection might have occurred between different worldwide isolates in Iraq. Furthermore, the first complete nucleotide sequence of an Iraqi ZYMV (ZYMV-Iq) isolate was done, using the Illumina sequencing technique. The complete nucleotide sequence of ZYMV-Iq isolate was 9650 nt, excluding the 3'poly (A) tail. ZYMV-Iq isolate shared the highest nt identity of 98.8% with an American (KC665630) isolate. Phylogenetic analysis based on the full genome sequence placed ZYMV-Iq in subgroup A of group I alongside 18 isolates from the US and two isolates from Australia. In addition, recombination analysis detected lone significant recombination between ZYMV-Iq and South Korean (AY279000) isolate. Moreover, the results showed that symptom intensity was varied across experimental host plants., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Dwarfism is an important agronomic trait in pumpkin that can increase yield. In this study, the dwarf Cucurbita pepo L. line X10 exhibited significantly longitudinally shorter cell length in the stem than did the normal-vine line JIN234. The dwarf stature of X10 was recovered with exogenous gibberellin (GA 3 ) application, suggesting that X10 might be sensitive to GA biosynthesis. Genetic analysis revealed that this dwarf trait is controlled by a single completely dominant locus: CpDw (Cucurbita pepo L. Dwarf). Using 1,300 F 2 individuals derived from a cross between X10 and JIN234, we mapped the CpDw locus to a region of approximately 24.6 kb on chromosome 10 that contain 5 annotated genes. The high expression level of Cp4.1LG10g05910.1 and high GA2ox enzyme activity in X10 revealed that the GA 2-oxidase gene Cp4.1LG10g05910.1 is a candidate gene for CpDw. Alignment of the Cp4.1LG10g05910.1 gene revealed two nonsynonymous single nucleotide polymorphism (SNP) mutations in the two exons, as well as several SNPs and InDels in the important functional elements of promoter between parental lines. Further allelic diversity analysis of the Cucurbita spp. germplasm resources indicated that Cp4.1LG10g05910.1 may be involved in vine growth during the early developmental stage in C. pepo but not in C. maxima or C. moschata. This study provides an important theoretical basis for the genetic regulation of vine length and crop breeding in pumpkin., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The effect of the rootstock on the acropetal and basipetal transport of photoassimilates and hormones was studied in the 'Kiran' (Ki) melon cultivar grafted onto pumpkin rootstocks with different degrees of compatibility. A complementary experiment was performed to compare the incompatible combination (as evidenced by plant collapse at the fruit ripening stage), designated Ki/r53, with self-grafted r53/r53 as a model compatible combination. Both experiments showed the accumulation of a number of amino acids, sugars, and sugar alcohols in the scion of the incompatible Ki/r53 grafts. Additionally, they showed a marked reduction of trans-zeatin-type cytokinins and an elevated content of cis-zeatin-type cytokinins in the rootstock, and the opposite pattern in the scion, hinting at the possible involvement of a hormonal signal for graft compatibility. There was no direct evidence of a blockage at the graft union, since hormone acropetal and basipetal trafficking was demonstrated for all combinations. Dye uptake experiments did not show xylem flow impairment. A possibly significant finding in the incompatible combination was the deposition of undifferentiated cells in the hollow space that replaces the pith region in melon and pumpkin. The link between the above findings and the collapse of the plants of the incompatible combination remains unclear., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: The fruit of Cucurbita ficifolia Bouché is known in Mexico as 'chilacayote'. The scientific interest that C. ficifolia Bouché has acquired is due to its important hypoglycemic effect. The present research aimed (i) to discover whether this hypoglycemic property is present at different stages of development of this fruit, and (ii) to characterize some bioactive compounds with antioxidant or anti-inflammatory properties. Ethylene production, respiration rate, and maturity indices were determined during fruit development. The chemical characterization of the aqueous extracts of each stage of maturity studied was determined and their hypoglycemic effects were bioassayed using groups of normal mice with diabetes induced by streptozotocin at a dose of 500 mg -1 kg -1 body weight., Results: Respiration rate and ethylene production showed a typical pattern for non-climacteric fruit and the quality parameters did not show significant changes. Phenolic compounds such as gallic acid and chlorogenic acid were found to have the highest concentration at 15 days of development. Extracts at 15 days showed a hypoglycemic effect that was 11% greater than that of glibenclamide in diabetized mice., Conclusion: All stages of development of C. ficifolia fruit had a hypoglycemic effect; however, the aqueous extract from the fruit at 15 days of development showed a better effect than glibenclamide. This finding highlights the potential of this maturity stage, and shows that it is appropriate for inclusion in treatments of type 2 diabetes mellitus. The results also indicate that phenolic compounds are mainly responsible for this effect and not d-chiro-inositol as previously thought. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Verticillium dahliae is a significant pathogen in cucurbit cropping systems for which there are limited control options outside of soil fumigation. Endophytes, fungi and bacteria that live within plant hosts without impacting the host negatively, have exhibited antagonism to V. dahliae. The objectives of this study were to survey potential V. dahliae-antagonistic endophytes from roots of 'Cinnamon Girl' pumpkin (Cucurbita pepo) grown under either polyethylene (PE), an experimental polylactic acid/ poly(hydroxalkanoate) (PLA/PHA) mulch, Weed Guard Plus, or no mulch, as well as from 'Sugar Baby' watermelon (Citrullus lanatus), and 'Tetsukabuto' squash (C. maxima x C. moschata). Four selected endophytes were screened for antagonism against V. dahliae in the laboratory, greenhouse, and field. A total of 777 isolates of potential fungal endophytes were recovered from pumpkin, watermelon, and squash roots between 2015 and 2016 of which 198 isolates were identified down to the genus level. Of those isolates, frequency of isolation was greatest for Dichotomopilus/Chaetomium spp. (5%), Cladosporium spp. (15.2 %), Clonostachys spp. (5.6 %), Epicoccum spp. (22.2 %), and Fusarium spp. (24.7 %). All five genera only weakly associated with roots grown under a particular mulch treatment (Cramer's V = 0.22) or cucurbit host (Cramer's V = 0.1925). In a laboratory culture plate assay, V. dahliae isolate JAW-113 was plated against one of four prospective endophytes (Dichotomopilus sp., Epicoccum sp., Microdochium sp., or Schizothecium sp.). The area under the Verticillium culture growth curve (AUVGC) was significantly highest (P < 0.0001) when V. dahliae was by Schizothecium sp. or Dichotomopilus sp. In a greenhouse study using a Mason jar assay with V. dahliae amended potting mix, pumpkin plant vigor, plant fresh weight, root fresh weight, and root dry weight were significantly higher (P < 0.05) for plants inoculated with Dichotomopilus sp., Epicoccum sp., Microdochium sp., and Schizothecium sp. compared to plants without endophyte inoculation. Subsequent field trials in 2017 and 2018 showed no significant differences in foliar disease severity or fruit yield, regardless of whether plants were inoculated with an endophyte or not. However, recovery of V. dahliae colony forming units from pumpkin stem sap was significantly lower (P < 0.0001) for plants inoculated with either Dichotomopilus sp. or Schizothecium sp. in 2017 or Dichotomopilus sp. in 2018., (Published by Elsevier GmbH.)

Pumpkins ( Cucurbita moschata ; Cucurbitaceae) are the rich source of nutrients and valued for their biologically active substances to be used for the treatment of several diseases. The contents, composition, and conformation of starch are the significant quality traits of C. moschata . Two germplasms were targeted for analysis regarding the taste difference. Results indicated that the total starch contents and amylose/amylopectin ratio were high in CMO-X as compared to CMO-E during each fruit development stage. Scanning electron microscopy and transmission electron microscopy observations revealed that smooth surface starch granules fused together to enhance the starch accumulation. For a comparison of fruit development in CMO-E and CMO-X, the putative pathway for starch metabolism was developed and homologs were identified for each key gene involved in the pathway. GBSS and SBE were correlated with the difference in the amylose/amylopectin ratio of CMO-E and CMO-X. Conclusively, the developmental regulation of genes associated with starch accumulation can be considered as an important factor for the determination of fruit quality.

Ethylene is the key regulator of sex determination in monoecious species of the family Cucurbitaceae. This hormone determines which individual floral meristems develop as female or male flowers and the female flowering transition. The sex determination genes discovered so far code for ethylene biosynthesis enzymes, but little is known about the importance of ethylene signaling components. In this paper we characterize two novel ethylene-insensitive mutations (etr1a-1 and etr1b) which block the female flowering transition of Cucurbita pepo; this makes plants produce male flowers indefinitely (androecy). Two missense mutations in the ethylene-binding domain of the ethylene receptors CpETR1A or CpETR1B were identified as the causal mutations of these phenotypes by using whole-genome resequencing. The distinctive phenotypes of single and double mutants for four etr mutations have demonstrated that the final level of ethylene insensitivity depends upon the strength and dosage of mutant alleles for at least three cooperating ETR genes, and that the level of ethylene insensitivity determines the final sex phenotype of the plant. The sex phenotype ranges from monoecy in ethylene-sensitive wild-type plants to androecy in the strongest ethylene-insensitive ones, via andromonoecy in partially ethylene-insensitive plants. The induction of female flowering transition was found to be associated with upregulation of CpACS11, CpACO2 and CpACS27, three ethylene biosynthesis genes required for female flower development. A model is proposed herein, integrating both ethylene biosynthesis and receptor genes into the genetic network which regulates sex determination in C. pepo., (© 2020 Society for Experimental Biology and John Wiley & Sons Ltd.)

Background: Pumpkins (Cucurbita moschata; Cucurbitaceae) are valued for their fruits and seeds and are rich in nutrients. Carotenoids and sugar contents, as main feature of pumpkin pulp, are used to determine the fruit quality., Results: Two pumpkin germplasms, CMO-X and CMO-E, were analyzed regarding the essential quality traits such as dry weight, soluble solids, organic acids, carotenoids and sugar contents. For the comparison of fruit development in these two germplasms, fruit transcriptome was analyzed at 5 different developmental stages from 0 d to 40 d in a time course manner. Putative pathways for carotenoids biosynthesis and sucrose metabolism were developed in C. moschata fruit and homologs were identified for each key gene involved in the pathways. Gene expression data was found consistent with the accumulation of metabolites across developmental stages and also between two germplasms. PSY, PDS, ZEP, CRTISO and SUS, SPS, HK, FK were found highly correlated with the accumulation of carotenoids and sucrose metabolites, respectively, at different growth stages of C. moschata as shown by whole transcriptomic analysis. The results of qRT-PCR analysis further confirmed the association of these genes., Conclusion: Developmental regulation of the genes associated with the metabolite accumulation can be considered as an important factor for the determination of C. moschata fruit quality. This research will facilitate the investigation of metabolic profiles in other cultivars.

Recycled paper has the potential to be used as a mulch for vegetable production and can be adopted for the cultivation of Italian zucchini. However, there have been no studies about the water savings or crop coefficient values used in irrigation management in this system; therefore, there is a need for more research. In view of the above, this study aimed to evaluate the effects of recycled paper mulch on evaporation and evapotranspiration in Italian zucchini and to determine the crop coefficients in its developmental stages. The study was carried out in two cultivation cycles conducted at the Lysimetric Station in Viçosa, MG, Brazil. The experiments were installed in a randomized block design with four replicates. Four lysimeter cultivation treatments were applied: without mulch (C); with recycled paper as mulch (CP); with only recycled paper (P); and with Bahia grass (G). Irrigation and drainage measurements were performed daily to calculate the crop and reference evapotranspiration, and thus the crop coefficient (Kc) values. The following characteristics were evaluated: fruit yield, NDVI and water productivity. For the cultivation of Italian zucchini using paper as mulch, Kc values of 0.54, 0.77 and 0.44 and Kcb values of 0.15, 0.45 and 0.18 are recommended for the initial, intermediate and final stages, respectively. NDVI can be used to estimate the Kc values for Italian zucchini. The use of recycled paper as mulch reduces the water consumption of Italian zucchini., Competing Interests: The authors have declared that no competing interests exist.

The onset of plant cultivation is one of the most important cultural transitions in human history 1-4 . Southwestern Amazonia has previously been proposed as an early centre of plant domestication, on the basis of molecular markers that show genetic similarities between domesticated plants and wild relatives 4-6 . However, the nature of the early human occupation of southwestern Amazonia, and the history of plant cultivation in this region, are poorly understood. Here we document the cultivation of squash (Cucurbita sp.) at about 10,250 calibrated years before present (cal. yr BP), manioc (Manihot sp.) at about 10,350 cal. yr BP and maize (Zea mays) at about 6,850 cal. yr BP, in the Llanos de Moxos (Bolivia). We show that, starting at around 10,850 cal. yr BP, inhabitants of this region began to create a landscape that ultimately comprised approximately 4,700 artificial forest islands within a treeless, seasonally flooded savannah. Our results confirm that the Llanos de Moxos is a hotspot for early plant cultivation and demonstrate that-ever since their arrival in Amazonia-humans have markedly altered the landscape, with lasting repercussions for habitat heterogeneity and species conservation.

Cucurbita maxima Duchesne squash and pumpkins are cultivated world-wide. Cucurbita maxima fruits are produced for fresh market and are valuable for food processing. Therefore, fruit characteristics and yield are the traits of high economic importance for breeders. To date, the genetic basis of fruit-associated traits in C. maxima have been poorly understood. In the present study, we evaluated fruit-associated traits and conducted quantitative trait locus (QTL) analysis using recombinant inbred lines (RILs) derived from a cross of two inbred lines with different fruit morphotypes. Phenotypic data for nine fruit traits (earliness, weight, number per plant, yield per plant, length and diameter, shape index, flesh thickness, sucrose content and dry matter content) were collected for RILs in two open-field experiments. Pairwise analysis of the phenotypic data revealed correlations among the fruit and yield-associated traits. Using a previously developed genetic map, we identified 26 QTLs for eight traits. The QTLs were found in 10 locations on eight chromosomes of C. maxima . The QTLs were detected across experiments and explained up to 41.4% of the observed phenotypic variations. Major-effect QTLs for multiple fruit-associated traits were clustered on chromosome 4, suggesting that this genomic region has been under selection during diversification and/or domestication of C. maxima .

The environment is the key factor that influences the host-parasite relationship. Elevated CO 2 levels resulting from various anthropogenic sources may directly affect the surroundings around pathogens and plants. It is hypothesized that plants may respond differently to pathogens in the environment containing an elevated concentration of CO 2 . To test the hypothesis an experiment was conducted to examine the effects of intermittent exposures of elevated levels of CO 2 viz., 400, 500 and 600 ppm (5 hr/day on alternate days) on the development of Sphaerotheca fuliginea causing powdery mildew disease on five cucurbits species using open-top chambers. The elevated levels of CO 2 acted as a growth promoter and significantly enhanced the plant growth of all five cucurbit species. Inoculation with the fungus incited specific mildew symptoms on the leaves and decreased the plant growth and biomass production of the cucurbits tested except bitter gourd. The intermittent exposures with elevated levels of CO 2 aggravated the disease development. As a result, severe mildew developed on all five cucurbits, including bitter gourd, which expressed tolerance to the pathogen. Fungus colonization in terms of the number of conidia/cm 2 leaf surface was significantly greater on the plants exposed to 500 or 600 ppm CO 2 . The stomata and trichome density and stomatal pore width were increased in the leaves of CO 2 exposed plants. The CO 2 exposures also accelerated the photosynthesis rate, but transpiration, stomatal conductance, salicylic acid and total phenols were decreased; fungus inoculation caused the effects just reverse of CO 2 . Interaction between S. fuliginea and CO 2 was found synergistic at 500 ppm, whereas with rest of the concentrations it was near to additive.

Powdery mildew (PM) caused by Podosphaera xanthii is one of the most important courgette diseases with high yield losses and is currently controlled by fungicides and sulphur applications in conventional and organic production. Plant derived elicitors/inducers of resistance are natural compounds that induce resistance to pathogen attack and promote a faster and/or more robust activation of plant defense responses. Giant knotweed (Reynoutria sachalinensis, RS) extract is a known elicitor of plant defenses but its mode of action remains elusive. The aim of this study was to investigate the mechanisms of foliar RS applications and how these affect PM severity and crop performance when used alone or in combination with genetic resistance. RS foliar treatments significantly reduced conidial germination and PM severity on both an intermediate resistance (IR) and a susceptible (S) genotype. RS application triggered plant defense responses, which induced the formation of callose papillae, hydrogen peroxide accumulation and the Salicylic acid (SA) - dependent pathway. Increased SA production was detected along with increased p-coumaric and caffeic acid concentrations. These findings clearly indicate that RS elicits plant defenses notably as a consequence of SA pathway induction.

High-throughput screening of an ethyl methanesulfonate-generated mutant collection of Cucurbita pepo using the ethylene triple-response test resulted in the identification of two semi-dominant ethylene-insensitive mutants: etr1a and etr2b. Both mutations altered sex determination mechanisms, promoting conversion of female into bisexual or hermaphrodite flowers, and monoecy into andromonoecy, thereby delaying the transition to female flowering and reducing the number of pistillate flowers per plant. The mutations also altered the growth rate and maturity of petals and carpels in pistillate flowers, lengthening the time required for flowers to reach anthesis, as well as stimulating the growth rate of ovaries and the parthenocarpic development of fruits. Whole-genome sequencing allowed identification of the causal mutation of the phenotypes as two missense mutations in the coding region of CpETR1A and CpETR2B, each one corresponding to one of the duplicates of ethylene receptor genes highly homologous to Arabidopsis ETR1 and ETR2. The phenotypes of homozygous and heterozygous single- and double-mutant plants indicated that the two ethylene receptors cooperate in the control of the ethylene response. The level of ethylene insensitivity, which was determined by the strength of each mutant allele and the dose of wild-type and mutant etr1a and etr2b alleles, correlated with the degree of phenotypic changes in the mutants., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Background: Portable handheld near infrared spectroscopy (NIRS) instruments currently present enormous advantages in terms of size, weight, and robustness. They also provide fast, precise information that can be obtained in situ, and they represent a viable option for controlling vegetable safety and quality during the growth period. The aim of this research was to evaluate three handheld portable NIRS instruments for in situ and real-time analysis of intact summer squashes. Traditional methods were used to analyze 221 summer squashes, and this work was used to develop calibration models for morphological, safety, and quality parameters. The longitudinal distribution of nitrate content in summer squashes weighing over 400 g was also studied, and the evolution of this parameter during the harvest period was tracked to determine which summer squashes and which zones of the vegetables (peduncle, equatorial, or stylar) could be earmarked for baby-food production., Results: The robustness of the calibration models confirmed the expectations raised by NIRS technology for morphological, safety, and quality control of individual summer squashes, and the models developed with the MicroNIR-1700 instrument were those that provided more accuracy and precision, being the peduncle zone the part with higher nitrate content., Conclusions: It is in the peduncle zone, therefore, where measurements of this parameter must be carried out to decide on the destination of the harvested product. Summer squashes picked at the end of the harvest are those that must be used for baby-food production. © 2019 Society of Chemical Industry., (© 2019 Society of Chemical Industry.)

We investigated changes in starch content and starch metabolic enzyme activities in developing and postharvest squash of distinct species, Cucurbita maxima and Cucurbita moschata, which accumulate high and low levels of starch, respectively. The total activity of starch phosphorylase in developing fruits significantly correlated (r = 0.99) to the amount of starch among Cucurbita species (C. maxima, C. moschata and C. pepo). Separable activity of a plastidial L-form phosphorylase in C. maxima fruit markedly increased corresponding with starch accumulation. We isolated two genes (CmPhoL1 and CmPhoH1) encoding an L-form and a cytosolic H-form phosphorylase from C. maxima fruit. The expression of CmPhoL1 in the fruit dramatically increased at the beginning of starch accumulation. Recombinant CmPhoL1 enzyme showed similar kinetic parameters in both glucan synthesis and phosphorolysis: this enzyme can catalyze the invertible reaction in vitro depending on the concentration of substrates. These results suggest that CmPhoL1 plays a role in the starch accumulation process during squash development, but the aid of other starch synthetic enzymes may be required for in vivo glucan synthesis reaction by CmPhoL1. An importance of plastidial starch phosphorylase in the starch accumulation in the fruit organ was indicated., (© 2018 Scandinavian Plant Physiology Society.)

The treatment of seeds and plants by electrically generated cold atmospheric pressure plasma can accelerate seed germination and radicle growing rates. The plasma generated reactive oxygen and nitrogen species, UV photons, and high frequency electromagnetic fields can penetrate into seed coats and modify their surface properties. Atomic force microscope data shows that cold helium or argon plasma induces strong corrugation of pumpkin seed coats, produces pores and surface defects. These structural deformations and poration enhance water uptake by seeds during the imbibing process, accelerate seeds germination, and increase seed growth. The cold atmospheric pressure plasmas treatment of pumpkin seeds also decreases the apparent contact angle between a water drop and the seed surface, thereby improving the wetting properties of seeds surfaces. Magnetic resonance imaging studies show acceleration of water uptake in pumpkin seeds exposed to a cold plasma jet. Reactive nitrogen and oxygen species, high frequency electromagnetic fields and photons emitted by the plasma jets accelerate germination of pumpkin seeds both independently and synergistically. These results show that cold plasma can be used in agriculture for acceleration of seed germination, increasing growth of plants seedlings, poration and corrugation of the bio-tissue surfaces., (Copyright © 2019 Elsevier B.V. All rights reserved.)

: Sex expression is a complex process, and in-depth knowledge of its mechanism in pumpkin is important. In this study, young shoot apices at the one-true-leaf stage and 10-leaf stage in Cucurbita maxima trimonoecious line '2013-12' and subandroecious line '9-6' were collected as materials, and transcriptome sequencing was performed using an Illumina HiSeq TM 2000 System. 496 up-regulated genes and 375 down-regulated genes were identified between shoot apices containing mostly male flower buds and only female flower buds. Based on gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, the differentially expressed genes were mainly enriched in the ethylene and auxin synthesis and signal transduction pathways. In addition, shoot apices at the 4-leaf stage were treated with the ethylene-releasing agent 2-chloroethylphosphonic acid (Ethrel), aminoethoxyvinyl glycine (AVG), AgNO 3 and indoleacetic acid (IAA). The number of female flowers up to node 20 on the main stem of '2013-12' increased significantly after Ethrel and IAA treatment and decreased significantly after AVG and AgNO 3 treatment. The female flowers in '9-6' showed slight changes after treatment with the exogenous chemicals. The expression of key genes in ethylene synthesis and signal transduction ( CmaACS7 , CmaACO1 , CmaETR1 and CmaEIN3 ) was determined using quantitative RT-PCR, and the expression of these four genes was positively correlated with the number of female flowers in '2013-12'. The variations in gene expression, especially that of CmaACS7 , after chemical treatment were small in '9-6'. From stage 1 (S1) to stage 7 (S7) of flower development, the expression of CmaACS7 in the stamen was much lower than that in the ovary, stigma and style. These transcriptome data and chemical treatment results indicated that IAA might affect pumpkin sex expression by inducing CmaACS7 expression and indirectly affecting ethylene production, and the ethylene synthesis and signal transduction pathways play crucial roles in pumpkin flower sex expression. A possible reason for the differences in sex expression between pumpkin lines '2013-12' and '9-6' was proposed based on the key gene expression. Overall, these transcriptome data and chemical treatment results suggest important roles for ethylene in pumpkin sex expression., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

This study investigates the effect of SPIONs (superparamagnetic iron oxide nanoparticles, ∼12.5 nm in size) on summer squash plant (Cucurbita pepo) in the presence and absence of supplementary iron (Fe(II)-EDTA). The plants were grown in nutrient solution with different iron sources: (i) Fe(II)-EDTA, (ii) without Fe(II)-EDTA (iii) SPIONs only, and (iv) Fe(II)-EDTA with SPIONs. Plant growth and development were assessed after 20 days of soaking by measuring phenological parameters such as plant biomass, chlorophyll content, amount of carotenoids, and the catalase enzyme activity. Transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy, X-ray diffraction, and vibrating sample magnetometer methods were used to detect uptake and translocation of SPIONs in plant tissues. Our results showed that SPIONs treatment (without Fe(II)-EDTA) caused growth retardation and decreased the plant biomass and chlorophyll content. Hence, they are not efficient sources to compensate for iron demand of squash plant. Electron microscopy observations, magnetization and elemental analyses revealed that SPIONs are taken-up by plant roots but not translocate to upper organs. In roots, SPIONs use a symplastic route for intercellular transfer. These findings suggest that as an iron source, SPIONs alone are not efficient for plant growth, but can contribute it together with Fe(II)-EDTA., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

The association of plant viruses with their vectors has significant implications for virus transmission and spread. Only a few studies, with even fewer pathosystems, have explored non-persistent (NP) virus-vector interactions that are presumed to be transient. We studied how a NP virus, Papaya ringspot virus (PRSV) influenced the behavior and biology of its vector, the melon aphid (Aphis gossypii Glover) and the non-vector, silverleaf whitefly (Bemisia tabaci Gennadius). We also assessed whether the fitness effects on aphids are modulated through changes in the host plant, squash (Cucurbita pepo L.) nutrient profile. The overall performance of A. gossypii was substantially higher on PRSV-infected plants, along with increased arrestment on PRSV-infected than non-infected plants. No such PRSV-modulated fitness effects were observed with B. tabaci. PRSV-infected plants had increased concentrations of free essential amino acids: threonine, arginine and lysine; non-essential amino acids: glycine and homocysteine; and soluble carbohydrates: galactose, raffinose and cellobiose. In general, PRSV encouraged long-term feeding and enhanced fitness of A. gossypii through host plant nutrient enrichment. These findings provide evidence for a NP virus mediated positive fitness effects on its vector, with no spillover fitness benefits to the non-vector within the same feeding guild.

Background: Zucchini fruit set can be limited due to unfavourable environmental conditions in off-seasons crops that caused ineffective pollination/fertilization. Parthenocarpy, the natural or artificial fruit development without fertilization, has been recognized as an important trait to avoid this problem, and is related to auxin signalling. Nevertheless, differences found in transcriptome analysis during early fruit development of zucchini suggest that other complementary pathways could regulate fruit formation in parthenocarpic cultivars of this species. The development of next-generation sequencing technologies (NGS) as RNA-sequencing (RNA-seq) opens a new horizon for mapping and quantifying transcriptome to understand the molecular basis of pathways that could regulate parthenocarpy in this species. The aim of the current study was to analyze fruit transcriptome of two cultivars of zucchini, a non-parthenocarpic cultivar and a parthenocarpic cultivar, in an attempt to identify key genes involved in parthenocarpy., Results: RNA-seq analysis of six libraries (unpollinated, pollinated and auxin treated fruit in a non-parthenocarpic and parthenocarpic cultivar) was performed mapping to a new version of C. pepo transcriptome, with a mean of 92% success rate of mapping. In the non-parthenocarpic cultivar, 6479 and 2186 genes were differentially expressed (DEGs) in pollinated fruit and auxin treated fruit, respectively. In the parthenocarpic cultivar, 10,497 in pollinated fruit and 5718 in auxin treated fruit. A comparison between transcriptome of the unpollinated fruit for each cultivar has been performed determining that 6120 genes were differentially expressed. Annotation analysis of these DEGs revealed that cell cycle, regulation of transcription, carbohydrate metabolism and coordination between auxin, ethylene and gibberellin were enriched biological processes during pollinated and parthenocarpic fruit set., Conclusion: This analysis revealed the important role of hormones during fruit set, establishing the activating role of auxins and gibberellins against the inhibitory role of ethylene and different candidate genes that could be useful as markers for parthenocarpic selection in the current breeding programs of zucchini.

The Cucurbitaceae family (cucurbit) includes several economically important crops, such as melon, cucumber, watermelon, pumpkin, squash and gourds. During the past several years, genomic and genetic data have been rapidly accumulated for cucurbits. To store, mine, analyze, integrate and disseminate these large-scale datasets and to provide a central portal for the cucurbit research and breeding community, we have developed the Cucurbit Genomics Database (CuGenDB; http://cucurbitgenomics.org) using the Tripal toolkit. The database currently contains all available genome and expressed sequence tag (EST) sequences, genetic maps, and transcriptome profiles for cucurbit species, as well as sequence annotations, biochemical pathways and comparative genomic analysis results such as synteny blocks and homologous gene pairs between different cucurbit species. A set of analysis and visualization tools and user-friendly query interfaces have been implemented in the database to facilitate the usage of these large-scale data by the community. In particular, two new tools have been developed in the database, a 'SyntenyViewer' to view genome synteny between different cucurbit species and an 'RNA-Seq' module to analyze and visualize gene expression profiles. Both tools have been packed as Tripal extension modules that can be adopted in other genomics databases developed using the Tripal system.

Background and Aims: In some plant families, including Cucurbitaceae, initiation and development of lateral roots (LRs) occur in the parental root apical meristem. The objective of this study was to identify the general mechanisms underlying LR initiation (LRI). Therefore, the first cellular events leading to LRI as well as the role of auxin in this process were studied in the Cucurbita pepo root apical meristem., Methods: Transgenic hairy roots harbouring the auxin-responsive promoter DR5 fused to different reporter genes were used for visualizing of cellular auxin response maxima (ARMs) via confocal laser scanning microscopy and 3-D imaging. The effects of exogenous auxin and auxin transport inhibitors on root branching were analysed., Key Results: The earliest LRI event involved a group of symmetric anticlinal divisions in pericycle cell files at a distance of 250-350 µm from the initial cells. The visualization of the ARMs enabled the precise detection of cells involved in determining the site of LR primordium formation. A local ARM appeared in sister cells of the pericycle and endodermis files before the first division. Cortical cells contributed to LR development after the anticlinal divisions in the pericycle via the formation of an ARM. Exogenous auxins did not increase the total number of LRs and did not affect the LRI index. Although exogenous auxin transport inhibitors acted in different ways, they all reduced the number of LRs formed., Conclusions: Literature data, as well as results obtained in this study, suggest that the formation of a local ARM before the first anticlinal formative divisions is the common mechanism underlying LRI in flowering plants. We propose that the mechanisms of the regulation of root branching are independent of the position of the LRI site relative to the parental root tip.

As one of the earliest domesticated species, Cucurbita pepo (including squash and pumpkin) is rich in phenotypic polymorphism and has huge economic value. In this research, using 1660 expressed sequence tags-simple sequence repeats (EST-SSRs) and 632 genomic simple sequence repeats (gSSRs), we constructed the highest-density EST-SSR-based genetic map in Cucurbita genus, which spanned 2199.1 cM in total and harbored 623 loci distributed in 20 linkage groups. Using this map as a bridge, the two previous gSSR maps were integrated by common gSSRs and the corresponding relationships around chromosomes in three sets of genomes were also collated. Meanwhile, one large segmental inversion that existed between our map and the C. pepo genome was detected. Furthermore, three Quantitative Trait Loci (QTLs) of the dwarf trait (gibberellin-sensitive dwarf type) in C. pepo were located, and the candidate region that covered the major QTL spanned 1.39 Mb, which harbored a predicted gibberellin 2-β-oxidase gene. Considering the rich phenotypic polymorphism, the important economic value in the Cucurbita genus species and several advantages of the SSR marker were identified; thus, this high-density EST-SSR-based genetic map will be useful in Pumpkin and Squash breeding work in the future.

Intensive agricultural landscapes can be hostile for bees due to a lack of floral and nesting resources, and due to management-related stress such as pesticide use and soil tillage. This threatens the pollination services that bees deliver to insect-pollinated crops. We studied the effects of farming intensity (organic vs. conventional, number of insecticide applications) and availability of semi-natural habitats at the field and landscape scale on pollinator visits and pollen delivery to pumpkin in Germany. We found that wild bumble bees were the key pollinators of pumpkin in terms of pollen delivery, despite fivefold higher visitation frequency of honey bees. Critically, we observed that the area of cropland had stronger effects on bees' pollen deposition than the area of seminatural habitats. Specifically, a 10% increase of the proportion of cropland reduced pollen delivery by 7%. Pumpkin provides a striking example for a key role of wild pollinators in crop pollination even at high numerical dominance of honey bees. In addition, our findings suggest that habitat conversion to agricultural land is a driver of deteriorating pollination. This underlines the importance to maintain sufficient areas of non-crop habitats in agricultural landscapes.

Soil salinity adversely affects the growth and yield of crops, including cucumber, one of the most important vegetables in the world. Grafting with salt-tolerant pumpkin as the rootstock effectively improves the growth of cucumber under different salt conditions by limiting Na⁺ transport from the pumpkin rootstock to the cucumber scion. High-affinity potassium transporters (HKTs) are crucial for the long distance transport of Na⁺ in plants, but the function of pumpkin HKTs in this process of grafted cucumber plants remains unclear. In this work, we have characterized CmHKT1;1 as a member of the HKT gene family in Cucurbita moschata and observed an obvious upregulation of CmHKT1;1 in roots under NaCl stress conditions. Heterologous expression analyses in yeast mutants indicated that CmHKT1;1 is a Na⁺-selective transporter. The transient expression in tobacco epidermal cells and in situ hybridization showed CmHKT1;1 localization at plasma membrane, and preferential expression in root stele. Moreover, ectopic expression of CmHKT1;1 in cucumber decreased the Na⁺ accumulation in the plants shoots. Finally, the CmHKT1;1 transgenic line as the rootstock decreased the Na⁺ content in the wild type shoots. These findings suggest that CmHKT1;1 plays a key role in the salt tolerance of grafted cucumber by limiting Na⁺ transport from the rootstock to the scion and can further be useful for engineering salt tolerance in cucurbit crops.

This study describes the approach of 1 H NMR metabolomic profiling for the differentiation of zucchini produced under different conditions of water irrigation (desalinated seawater -0.397 dS/m, 0.52 €/m 3 vs groundwater -2.36 dS/m, 0.29 €/m 3 ) and ventilation (surface area of the vent openings/greenhouse area was 15.0% for one sector and 9.8% for the other). Overall, 72 extracts of zucchini ( Cucubirta pepo L. cv Victoria) under four different conditions were regularly analyzed during the spring-summer cycle from April to July 2017. We have found that zucchini plants irrigated with desalinated seawater increased the zucchini production yield, presented fruits with higher concentration of glucose, fructose, and vitamin B3, and displayed an increased antioxidant activity. On the contrary, plant groundwater irrigation produced the increment of sucrose level that could rise the sweetness perception of the fruits. Finally, the ventilation variable produced a higher concentration of trigonelline, histidine, and phenylalanine but only on those zucchinis irrigated with groundwater.

Brassinosteroids (BRs) are considered to possess protective activity in plants exposed to various stresses. The present study was conducted to evaluate the effects of 24-epibrassinolide (EBL) on salt stressed summer squash cv. Eskandrani seedlings, whether it can alleviate the deleterious effects of salt stress in growing seedlings or not. For this, summer squash seeds were germinated in solidified half strength MS (Murashige and Skoog) medium supplemented with different concentrations and combinations of EBL (0, 5, 10 and 20 μM) and NaCl (0, 50, 100 and 150 mM). The different concentrations (5, 10, 20 μM) of EBL significantly increased germination percentage and seedling growth capacity and the greatest increase was observed at 10 μM EBL. EBL application significantly increased the contents of photosynthetic pigments, the relative water content and the uptake of K and Ca. However, the different concentrations (50, 100 and 150 mM) of NaCl significantly decreased the above-mentioned attributes. The different concentrations (50, 100 and 150 mM) of NaCl significantly increased the electrolyte leakage, the lipid peroxidation and the Na uptake, but the interaction between EBL and NaCl significantly decreased these parameters. The results of this study proved that the application of 24-epibrassinolide to growing squash seedlings under salt stress conditions reduced the deleterious effects of salt stress and increased the tolerance of seedlings to its detrimental effects.

Spotted (Diabrotica undecimpunctata howardii) and striped (Acalymma vittatum) cucumber beetles (Coleoptera: Chrysomelidae) are serious pests of field-grown cucurbits in most areas of the United States where these crops are grown. This study aimed at quantifying, using a comparative approach, the behavioral response of A. vittatum and D. u. howardii to visual and olfactory cues associated with different trap types. In a first field study, Pherocon corn rootworm (CRW) traps baited with a 5-component floral-based lure (= AgBio lure) captured significantly more A. vittatum than traps baited with any other commercial lure. When used in combination with yellow sticky cards, the AgBio lure outperformed the other lures except for the Trécé lure TRE8274. Subsequent tests revealed that the response of both cucumber beetle species to the AgBio lure was positively associated with increases in the amount of lure used. In the last series of tests that involved color discrimination by the beetles, traps constructed using 3.8-liter jugs painted yellow outperformed the CRW trap. Results from on-farm research, conducted at a commercial vegetable farm, confirmed the beetles' visual preference for yellow, and also revealed an excellent performance of the mass trapping system, which kept cucumber beetle densities in the cash crop below economic thresholds. Combined findings indicate that the mass trapping system developed can be implemented as part of a broader IPM program aimed at managing cucumber beetles.

The distribution of surface modified carbon dots (CDs) in the pumpkin seedlings was studied by visualization techniques and their potential phytotoxicity was investigated at both the physiological and biochemical levels. The average size of carbon dots was approximately 4 nm. The fluorescent peaks of bared CDs, CD-PEI and CD-PAA were between 420 nm and 500 nm, indicating CDs could emit blue and green fluorescence. Fluorescent images showed that all three types of CDs could accumulate in the pumpkin roots and translocate to the shoots, although the distribution pattern of each CDs was obviously different. At the biochemical level, the elevated antioxidant enzymes in pumpkin roots suggest that all the CDs could potentially trigger the antioxidant defense systems in pumpkin seedlings. Additionally, such alteration was greater in the roots than in the shoots. Our study represents a new perspective on CD visualization in plant tissues and provide useful information for the potential toxicity of different types of CDs to terrestrial plants, which is of importance to agricultural application.

Winter cover crop mulches can diversify agricultural habitats and provide a range of benefits for crop production and pest management. Here we report the influence of strip tilled winter cover crop mulches on arthropod abundance in organic vegetable plots. Crookneck squash (Cucurbita pepo L.; Cucurbitales: Cucurbitaceae) was direct seeded into mowed and strip tilled barley (Hordeum vulgare L.; Poales: Poaceae), crimson clover (Trifolium incarnatum L.; Fabales: Fabaceae), a barley + crimson clover mixture, or a no-cover crop control. Arthropods on squash plants were assessed weekly using visual counts. Seed predation was assessed using weed seed arenas. In 2013, mixed species cover crops produced the most ground cover, fewest weeds, and largest squash plants, but herbivore and predator abundance were not correlated with any of those factors. In 2014, mixed species cover crops again produced the most ground cover and fewest weeds, but the largest squash plants were found in no-cover crop control plots, which also had the highest herbivore abundance per plant. Predator and herbivore abundance were positively correlated with squash plant size in 2014. There were no differences in seed predation across treatments. Differences in ground cover biomass and weed presence between the 2 yr may have contributed to differences in squash plant quality and subsequent herbivore abundance between seasons. Results suggest that arthropods on plants responded largely indirectly to cover crops through host plant quality. Results are interpreted in light of overall costs and benefits of cover cropping.

Plants response to symbiosis with arbuscular mycorrhizal fungi (AMF) under water stress is important to agriculture. Under abiotic stress conditions native fungi are more effective than exotics in improving plant growth and water status. Mycorrhization efficiency is related to soil fungi development and energy cost-benefit ratio. In this study, we assessed the effect on growth, water status and energy metabolism of Cucurbita pepo var. pepo when inoculated with native AMF from the Sonoran desert Mexico (mixed isolate and field consortium), and compared with an exotic species from a temperate region, under drought, low and high salinity conditions. Dry weights, leaf water content, water and osmotic potentials, construction costs, photochemistry and mycorrhization features were quantified. Under drought and low salinity conditions, the mixed isolate increased plant growth and leaf water content. Leaf water potential was increased only by the field consortium under drought conditions (0.5-0.9MPa). Under high salinity, the field consortium increased aerial dry weight (more than 1g) and osmotic potential (0.54MPa), as compared to non-mycorrhized controls. Plants inoculated with native AMF, which supposedly diminish the effects of stress, exhibited low construction costs, increased photochemical capacity, and grew larger external mycelia in comparison to the exotic inoculum., (Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.)

Hexachlorobutadiene (HCBD) has been listed as a persistent organic pollutant (POP) in the Stockholm Convention, and is now drawing more and more research interest. However, the understanding of its bioaccumulation, especially in plants, is still very limited. In this work, the behavior of HCBD in aqueous solution and pumpkin seedlings was studied through in-lab hydroponic exposure experiments. It was found that 69% of HCBD volatilized from water to the atmosphere after one day of exposure, and only 1% remained in the solution after four days. This high volatility might be the main cause of the low HCBD levels in aqueous environments. Although a great amount of HCBD volatilized into the atmosphere, only a small proportion of airborne HCBD was captured by the leaves and stems of the blank pumpkin seedling controls. The translocation of HCBD from the leaves to the bottom roots, as well as its release from the roots into the water, was detected. For the exposure groups, the pumpkin seedlings absorbed HCBD from both the hydroponic solution and the air via the roots and leaves, respectively. The concentration of HCBD in the exposed pumpkin roots linearly increased with the continuous addition of HCBD into the exposure system. Upward translocation from the roots to the leaves and downward translocation from the leaves to the roots existed simultaneously in the exposed pumpkin seedlings. However, the concentrations of HCBD in the leaves, stems and roots in the exposure group were much higher than those of the blank plant controls, suggesting little contribution from the airborne HCBD in the hydroponically exposed pumpkin seedlings. The lipid content did not show obvious effects on the bioaccumulation and biodistribution of HCBD in the pumpkin seedlings, indicating that the translocation of HCBD within the pumpkin seedlings might be an active process. This study provided new findings on the environmental behavior of HCBD, which will be helpful for understanding the exposure risks.