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The fungus Fusarium oxysporum f. sp. lycopersici (FOL) is known to cause vascular wilt on tomato almost over the world. Inoculation of FOL reduced plant growth and increased wilt of tomato. The following study examined the possible role of arbuscular mycorrhizal fungi (AMF) consortium comprising of Rhizophagus intraradices, Funneliformis mosseae and Claroideoglomus etunicatum against FOL in tomato and explored in an inducing plant systemic defense. AMF inoculation reduced the wilt disease within vascular tissue and in vivo production of fusaric acid was observed which may be responsible in reduced wilting. FOL had an antagonistic effect on AMF colonization, reduced the number of spores, arbuscules and vesicles. AMF also inhibited the damage induced by Fusarium wilt through increasing chlorophyll contents along with the activity of phosphate metabolising enzymes (acid and alkaline phosphatases). Moreover, tomato plants with mycorrhizal inoculation showed an increase in the level of antioxidant enzymes including glutathione reductase, catalase, and etc. with an ultimate influence on the elimination of reactive oxygen species. Moreover, rise in phosphatase along with antioxidant enzymatic systems and enhanced photosynthetic performance contributed to induced resistance against FOL in tomato.

Background Late embryogenesis abundant (LEA) proteins were reported to be related to adversity stress and drought tolerance. Lea-3 from Arachis hypogaea L. (AhLea-3) was previously found to be related to salt tolerance according to the result of transcriptome profiling and digital gene expression analysis. So, AhLea-3 was cloned and the salt tolerance was validated by transgenic peanut plants. Results AhLea-3 was isolated from M34, a salt-resistant mutant of peanut, with its cDNA as the template. AhLea-3 contains one intron and two extrons, and the full-length cDNA sequence contains 303 bp. AhLea-3 was ligated to pCAMBIA1301 to obtain the overexpression vector pCAMBIA1301-AhLea-3, which was then transferred into peanut variety Huayu23. The expression level of AhLea-3, as determined by qRT-PCR analysis, was >10 times higher in transgenic than in non-transgenic plants. Five days after they were irrigated with 250 mM NaCl, the transgenic plants showed less severe leaf wilting, higher activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase), and lower malonic dialdehyde content than non-transgenic plants. Relative to non-transgenic plants, the transgenic plants had a higher photosynthetic net rate, stomatal conductance, and transpiration rate, and a lower intercellular CO2 concentration after salt stress treatment (250 mM NaCl). Conclusions These results indicate that overexpression of AhLea-3 increased the salt tolerance of transgenic peanut plants. AhLea-3 might become a useful gene resource for the variety breeding of salinity tolerance in peanut. How to cite: Qiao L, Jiang P, Tang Y, et al. Characterization of AhLea-3 and its enhancement of salt tolerance in transgenic peanut plants. Electron J Biotechnol 2021;49. https://doi.org/10.1016/j.ejbt.2020.10.006

Tomato (Lycopersicon esculentum) is one of the widely grown vegetables worldwide. Fusarium oxysporum f. sp. lycopersici (FOL) is the significant contributory pathogen of tomato vascular wilt. The initial symptoms of the disease appear in the lower leaves gradually, trail by wilting of the plants. It has been reported that FOL penetrates the tomato plant, colonizing and leaving the vascular tissue dark brown, and this discoloration extends to the apex, leading to the plants wilting, collapsing and dying. Therefore, it has been widely accepted that wilting caused by this fungus is the result of a combination of various physiological activities, including the accumulation of fungal mycelia in and around xylem, mycotoxin production, inactivation of host defense, and the production of tyloses; however, wilting symptoms are variable. Therefore, the selection of molecular markers may be a more effective means of screening tomato races. Several studies on the detection of FOL have been carried out and have suggested the potency of the technique for diagnosing FOL. This review focuses on biology and variability of FOL, understanding and presenting a holistic picture of the vascular wilt disease of tomato in relation to disease model, biology, virulence. We conclude that genomic and proteomic approachesare greater tools for identification of informative candidates involved in pathogenicity, which can be considered as one of the approaches in managing the disease. Keywords: Fusarium oxysporum f. sp. lycopersici, Pathogenicity, Biology, Diversity, Lycopersicon esculentum, Vascular wilt

Cashew (Anacardium occidentale L.) is composed of two distinct parts: the nut (fruit), which represents only 10% of the total weight of the harvested product, and the cashew apple (pseudo-fruit), usually known as cashew. This study aimed to determine the hydrocooling temperature of cashew apples and its effects on quality maintenance. Cashews were hydrocooled (HC) by immersion in chlorinated water at 1, 3, 5 and 7 °C. Fruit were cooled in a refrigerator at 5 °C as controls. After treatments, all the fruit were stored at 5 °C for 15 d, and cooling rate, color, freshness, visual assessment, weight loss, and thermal properties were evaluated. Fruit hydrocooled at 1 and 7 °C had lower visual quality and wilting, and greater weight loss, 3 °C was discarded by did not show evident results. A temperature of 5 °C was selected for further studies. Cashew apples were HC at 5 °C, and control treatment cooled in display cold room (CR) at 5 °C, and then fruit from both treatments were stored for 25 days. Samples were taken for physical, physico-chemical and enzymatic analyses at 5 days intervals. HC fruit showed greater freshness, higher firmness and acidity, and slower losses of fresh weight loss and vitamin C when compared with CR. Total phenolic contents decreased during storage, but little effect of treatment on the rate of decline was detected. However, activities of polyphenol oxidase and peroxidase were generally higher in cashew apples with CR than after HC. Red color loss of the cashew apples was constant during storage, regardless of the cooling method. Our study shows that 5 °C is the minimal temperature for hydrocooling of cashew apples, to decrease the risk of damage by cooling, and that this temperature is the optimal temperature for storage of cashew apples

Interactions between the fungal symbionts of the polyphagous shot hole borer (PSHB) Euwallacea nr. fornicatus and avocado host trees of cultivars 'Hass' and 'Ettinger' were studied, with emphasis on the three symbiotic fungi of the beetle. Fusarium euwallaceae did not spread far from the beetle galleries and remained viable in live xylem for 25 months; Graphium euwallaceae and Paracremonium pembeum disappeared from the live tissue 2 months after inoculation, but remained viable in dead xylem. The role of F. euwallaceae as a pathogen that contributes to typical wilting symptoms of PSHB-colonized avocado branches was assessed. The enhanced resistance of 'Ettinger' than of 'Hass', as manifested in its fewer beetle attacks was not reflected in the interaction of these cultivars with the symbiotic fungi. The specific pseudo-pathogenic interaction of F. euwallaceae with the xylem may be the key to understanding the different susceptibility between attacked hosts.

Hydroponic root mats (HRMs) are a green technology for various wastewaters purification. However, plants wilting will inevitably reduce the purification efficiency of HRMs. Harvesting as an important way of plant management for a better understanding of sustainability of HRMs has always been highly controversial. The goal of this study was to investigate the impacts and sustainability of harvesting on nitrogen removal and greenhouse gases (CH4, N2O) emissions of the two kinds of enhanced hydroponic root mats: autotrophic hydroponic root mat (AHRM) and heterotrophic hydroponic root mat (HHRM) for treating secondary effluent. The results showed that harvesting temporarily decreased nitrogen removal efficiency of the two systems, and removal efficiency recovered quickly because of the existence of external electron donors. The effects of harvesting are ordered as: HHRM > AHRM, NO3−-N > NH4+-N. Increasing C/N, S/N would reduce the impact of temperature on harvesting systems. Harvesting also increased the emission of greenhouse gases, and increasing C/N(=6), S/N(=1.1) could significantly reduce greenhouse gases emission of the harvesting systems at low temperature. In addition, composition analysis of the shoots of the harvested plants was also conducted, and the results showed that N contents of growing shoots were significantly higher than that of withered shoots. In order to make the hydroponic root mats sustainable, harvesting before the plants wilt is more effective in removing nitrogen from the system permanently and maintain a sustainable system.

The long-term performance of green infrastructures (e.g., vegetated slopes, green roof, bio-retention systems, etc.) can be affected by the wilting of vegetation (i.e., tendency of evapotranspiration (ET) to be nil) attributed to the decrease in volumetric soil water content. Therefore, it is important to explore an approach to investigate the wilting time of vegetation so that mitigation measures can be taken to ensure the serviceability of green infrastructure. The technical note aims to 1) conduct probabilistic analysis of volumetric soil water content in slopes vegetated with non-crop tree and grass species; and 2) further explore this analysis method for estimating probability of wilting (tendency of transpiration becoming nil) of the selected vegetation species under natural climate conditions. For this investigation, two non-crop species namely, Ivy tree (Schefflera heptaphylla) and Bermuda grass (Cynodon dactylon), commonly grown in subtropical regions in world were selected. A normal distribution was found as the best fit to the measured volumetric water content under the impact of both species. The estimated mean value was found significantly higher in Cynodon dactylon slope compared with that of Schefflera heptaphylla slope, while the coefficient of variation among the species is similar. The probability of wilting of C. dactylon is found lower than that of Schefflera heptaphylla. In the present study, the significance of using probabilistic approach for characterizing the distribution of volumetric soil water content to assess the reliability of vegetated infrastructure was highlighted. The study is useful for estimating the behaviour of vegetation for better planning of restoration and rehabilitation measures. This differs from those in agricultural fields with the usually shorter period for monitoring of vegetation growth (mostly within 3 months), and they are usually subjected to controlled manual irrigation.

In the present study, the essential oil (EO) of Hyptis suaveolens has been explored for the first time for its phytotoxic and cytotoxic activities. The phytotoxic activity was assessed against rice (Oryza sativa) and its major troublesome weed, Echinochloa crus-galli, under laboratory and screenhouse conditions. GC-MS analysis revealed EO to be monoterpenoid (~ 79% monoterpenes) in nature with α-phellandrene (22.8%), α-pinene (10.1%) and limonene (8.5%) as the major chemical constituents. The laboratory bioassay showed a complete growth inhibitory effect of EO (≥ 2 mg mL−1) towards the germination and seedling growth of E. crus-galli. However, the inhibitory effect on rice was much less (~40% inhibition). EO caused visible injury, reduction in chlorophyll content, cell viability and ultimately led to complete wilting of E. crus-galli plants. In addition, EO altered the cell division in the meristematic cells of Allium cepa as depicted by ~63% decrease in mitotic index. EO exposure induced several aberrations at chromosomal (c-mitosis, anaphase bridges, chromosomal breakage, vagrant chromosomes, and sticky chromosomes) and cytological level (cytoplasm destruction, peripheral nuclei, and bi-nucleate cells). The present study concludes that H. suaveolens EO possesses phytotoxic activity due to its mito-depressive activity, and could serve as a natural herbicide under sustainable agricultural practices.

Aphanomyces root rot (ARR) of field pea (Pisum sativum), caused by Aphanomyces euteiches, can cause severe root damage, wilting, and large yield losses under wet soil conditions. To identify ways to manage this disease, the effect of A. euteiches inoculum density on field pea was studied under greenhouse and field conditions in 2015 and 2016. Increases in inoculum density reduced seedling emergence, root nodulation, and plant vigor, and resulted in increased root rot severity in both field and greenhouse tests. Seed treatments with the fungicides Apron Advance (thiabendazole + fludioxonil + metalaxyl) + Vibrance (difenoconazole + metalaxyl-M + sedaxane), INTEGO Solo (ethaboxam), BAS 516F (boscalid + pyraclostrobin), BAS 720F (metalaxyl + pyraclostrobin + fluxapyroxad), and BAS 516F + BAS 720F (3:1) were evaluated for their efficacy against ARR. All seed treatments except Apron Advance + Vibrance reduced root rot severity under controlled conditions. BAS 516F, BAS 720F and INTEGO Solo improved plant vigor and all treatments reduced seedling blight to varying degrees under greenhouse conditions, but not in the field. A collection of 22 pea genotypes was evaluated for resistance to root rot in field plot experiments. Line 00–2067 showed the least severe root rot symptoms, whereas ‘Spring D’ showed the lowest reduction in yield. The results suggest that there may be an opportunity to combine partial host resistance and fungicidal seed treatments to adequately manage ARR of field pea. Keywords: Aphanomyces euteiches, Field pea, Fungicides, Inoculum density, Resistance

Gardenias (Gardenia jasminoides Ellis var. ‘fortuniana’) have commercial importance as cut foliage but are prone to severe postharvest water deficit and quick wilting. Herein, we investigated the efficacy of pretreatment with nano-silver (NS), a strong antibacterial agent, in enhancing water relations and the vase life of cut gardenia foliage. Compared with the deionized-water controls, pretreatment with NS at 10, 15, 20, 25, or 30 mg L−1 for 24 h significantly extended the vase life of cut gardenias. The most effective NS concentration was 15 mg L−1, which promoted the longest (15.2 days) vase life extension, i.e., 310.2% of that of the control treatment. In addition, pretreatment with 15 mg L−1 NS effectively delayed wilting by maintaining a higher water balance value and relative fresh weight when compared with untreated cut foliage. Scanning electron microscopy revealed that these higher values were due to an improved water uptake as a result of the alleviation of bacterial xylem blockage at the stem-ends. Furthermore, Ag concentration was remarkably higher at the stem-ends of NS-pretreated cut gardenias than in any other tissues. Overall, these results demonstrate that NS pretreatment effectively inhibited bacterial growth at the cut stem-ends, and helped maintain a favorable water balance, thereby delaying wilting and extending the vase life of cut gardenias.

Unlike many of the fresh-cut popular leafy vegetables whose deterioration becomes apparent in wilting and browning, fresh-cut pepper (Capsicum spp.) undergoes subtler visible changes. The current study investigated hyperspectral fluorescence imaging as an alternative to monitor the physical changes to sliced pepper rings in cold storage (4 °C, 0–21 d). Five accessions of bell-type pepper and an equal number of jalapeno-type pepper accessions were prepared by routine fresh-cut operation and placed in cold storage. At weekly intervals, pepper samples were scanned by UV-excited (365 nm) hyperspectral fluorescence imaging (464–799 nm response range), whereupon quantitative and qualitative modeling was performed in trials to respectively a) model electrolyte leakage percentage by partial least squares regression, and b) compare storage days by linear discriminant analysis (LDA). LDA classification models were moderately successful at distinguishing post-cut storage times 0, 7, 14, and 21 d. As with previous studies on the physiological effects of slicing peppers, the fluorescence response was variable across accessions within pepper type and between the two pepper types studied, which is attributed to the complicating effects of fluorescence reabsorption and cell injury response and genotypic differences that influence suitability for fresh-cut applications among the accessions evaluated.

This study aimed to evaluate the evolution of physical and physicochemical characteristics of white-fleshed dragon fruit during its development. Correlations between external color and the main pulp quality variables were analyzed. Important characteristics were observed throughout fruit development, such as increase in pulp weight and yield, pH, and soluble solids and decrease in weight and thickness, firmness, and moisture. The visual changes in different development stages showed their potential use as morphologic markers in the determination of fruit ripening, especially the appearance of fruit scales. Based on the analyzed variables, the ideal harvest time indicated for commercialization in the short or medium term is between 34–38 days after anthesis. After 40 days, the fruit becomes less visually attractive because of scale wilting and loss of the intense pink color of the skin; although, up to 42 days, they possess adequate internal quality to be consumed, and may be also used for processing.

Potato blackleg is a tuber-borne bacterial disease caused by species within the genera Dickeya and Pectobacterium that can cause decay of plant tissue and wilting through the action of cell wall degrading enzymes released by the pathogen. In case of serious infections, tubers may rot before emergence. Management is largely based on the use of pathogen-free seed potato tubers. For this, fields are visually monitored both for certification and also to take out diseased plants to avoid spread to neighboring plants. Imaging potentially offers a quick and non-destructive way to inspect the health of potato plants in a field. Early detection of blackleg diseased plants with modern vision techniques can significantly reduce costs. In this paper, we studied the use of deep learning for detecting blackleg diseased potato plants. Two deep convolutional neural networks were trained on RGB images with healthy and diseased plants. One of these networks (ResNet18) was experimentally found to produce a precision of 95 % and recall of 91 % for the disease class. These results show that convolutional neural networks can be used to detect blackleg diseased potato plants.

There is a great need to make biological control research applicable to local political and social situations. The objectives of this study were to evaluate the effect of Fusarium oxysporum isolates against opium poppy (Papaver somniferum) and verify their potential as biocontrol agent. For this, a 2-year experiment was carried out under glasshouse (2 trials) and field conditions (2 trials). From infected poppy plants, a total of 16 pathogenic fungal strains were identified as F. oxysporum and used for the experiments. The isolates Ghr18, Ghr5-2, Mr28 and Ghr5-4 caused the highest wilting symptoms on sample plants (P 0.5). Moreover, the results showed a clear host specificity of the selected pathogenic isolates. These results suggest that Fusarium isolates have the potential to be used as biological control agents against poppy plants in the Middle East.

Grass is an abundant feedstock which is commonly used as animal fodder. It can also be utilized for bio-production, however its availability is generally not consistent through time. Storage is therefore an economic necessity to ensure continuous, steady supply for bioprocessing. Extrusion tests were performed, before or after Ca(OH)2 addition (75, 100 or 200 g kg−1 total solid (TS) of grass), with the objective to achieve 3 months storability without major carbon loss. The performances were determined by the changes in biomass characterisation, methane production through anaerobic digestion and carboxylate production through fermentation, in three storage conditions: fresh (no storage), and afterensiling or wilting for 3 months. For wilting, Ca(OH)2 addition of 100 and 200 g kg−1 TS before extrusion, and 200 g kg−1 TS after extrusion significantly preserved the biomass. For ensiling, the biomass were well preserved. Ensiling with Ca(OH)2 addition of 100 g kg−1 TS before extrusion was found the optimum preservation method in this study, with methane production of 237 ± 10 (test) vs 265 ± 29 (initial control) cm3 g−1 VSinitial CH4, and carboxylate production of 124 ± 8 (test) vs 109 ± 4 (initial control) mg g−1 VSinitial Carbon. Especially when storage conditions were sub-optimal (wilting), addition of 100 g kg−1 TS Ca(OH)2 before extrusion outperformed the non-treated, wilted condition to a large extent (178 ± 18 vs 50 ± 8 cm3 g−1 VSinitial CH4 and 86 ± 17 vs 18 ± 4 mg g−1 VSinitial Carbon). Overall, combined extrusion and alkali pretreatment improves grass storability.

In this study, the effects of drought stress on gas exchange and water relations of the invasive weed Chromolaena odorata were investigated. Drought stress was induced in potted plants by withholding water. The responses of drought stressed plants (DS) were then compared to well-watered (WW) controls. Measurements of diurnal gas exchange and chlorophyll fluorescence parameters were taken initially and every two days after water was withheld to day 10. Maximum CO2 uptake in WW plants ranged from 10.5 to 12.8 μmol m−2 s−1 while in the DS treatment values decreased from 9.3 μmol m−2 s−1 on day 0 to 3.95 μmol m−2 s−1 on day 10. Trends in diurnal leaf conductance and transpiration in DS and WW plants were similar to those for CO2 uptake. In WW plants, maximum quantum yield (Fv/Fm) of Photosystem II (PS II) was high, while in the DS treatment, it decreased significantly from day 2 to day 10. Leaf water potential (Ψ) was high in WW plants and significantly lower in DS plants. Water use efficiency (WUE) and proline concentrations were low in WW plants and increased significantly with drought stress. The photosynthetic rates in C. odorata suggest a high capacity for light utilization and water absorption and transport to leaves. Early stomatal closure and significant reductions in stomatal conductance suggest that C. odorata may be considered as a drought-avoider species which is sensitive to water deficit and responds by rapid wilting and leaf abscission. Our study provides empirical evidence for links between plant functional traits and the ecological success of an important invasive species.

The importance of rice resistance to abiotic stress has largely been attributed to signal-induced closure of stomata, protection of antioxidase enzymes, and osmotic adjustment of sugars, etc. However, regulation role of nodes in water flow under drought stress has not been reported. Two rice genotypes Z4 and its recombinant inbred line (RIL) were subjected to drought stress for 10 d at the pollen mother cell meiosis stage. Results indicated a higher decline in spikelet fertility was found in RIL than Z4 plants under drought stress compared with the corresponding control. However, the leaves of Z4 plants were wilting 1 d earlier than those of RIL plants under drought stress. Accordingly, a greater decline in the RWC and water potential of the leaf and sheath, but a lower decrease in the panicle, was observed in the Z4 plants than the RIL plants. In the process, higher decrease in transpiration rate of leaf, hydraulic conductance, diameter of the xylem vessel and relative expression level of aquaporins (AQP) genes of node were observed in Z4 than RIL plants under drought stress compared with the corresponding control. Thereby, we deduced that the node act as a “node switch” to control panicle water status by mediating the hydraulic resistance through changing the xylem diameter and the expression level of AQP genes under drought stress.

Date palm (Phoenix dactylifera L.) fruit wilting disorder, caused by the high increase in temperature and decrease in relative humidity of the environment, is more prevailing due to climate change over the last decades. This has affected negatively the economy of single-product palm growers. The physiological effects of deficit irrigation on ‘Mazafati’ date palm during four months, starting from two months before flowering (early January) up to two months after flowering which is concomitant with the middle of the Kimri stage (late April) was investigated. Two irrigation levels of 100% ETc and 70% ETc at three irrigation intervals of 50, 100 and 150 mm cumulative evaporation in two locations with different average daily and annual temperatures in Sistan and Baluchestan province of Iran were compared. Deficit irrigation at intervals of 100 mm evaporation resulted to the highest bunch weight and yield in two orchards and, the highest water use efficiency was obtained in the location 2 (warmer area). Wilting percentage of bunch was not affected by irrigation levels, but the irrigation interval at 100 mm evaporation showed the best control. The increase in mean weight of fruit was observed only in the location 1 with irrigation intervals of 50 and 100 mm evaporation. The highest amount of soluble solids and soluble sugars was obtained in the second location with irrigation interval at 150 mm evaporation. Total phenolic compounds and fruit starch showed the lowest and highest with full irrigation, respectively. Deficit irrigation at all three irrigation intervals increased the activity of peroxidase and polyphenol oxidase in fruits and leaves. Reduction of calcium and iron of leaf during the disorder was observed with deficit irrigation at different irrigation intervals. However, reduction in leaf zinc was observed only at 150 mm irrigation interval. According to the results, irrigation level of 70% with 100% did not show a significant difference in fruit qualitative properties, and irrigation at 100 mm evaporation intervals before the disorder risk period is recommended to control the disorder. It seems to be a more increasing in percentage or duration of deficit irrigation on date palm in future researches to be promising.

Postharvest water loss causes fruit softening, wilting, and a decline in quality and commodity value. Cuticular wax is a key barrier against non-stomatal water loss and plays a crucial role in fruit quality maintenance. However, there has been limited research on the genetic basis of fruit wax and postharvest water loss. Here, we found that HJ (Citrus reticulata) and ZK (Poncirus trifoliata) fruit had significant differences in postharvest water loss and cuticular wax. HJ fruit had a lower wax content and a faster water loss, and the main aliphatic wax components were alkanes and aldehydes. By contrast, ZK fruit had a higher wax content and a slower water loss, and the main aliphatic wax components were only alkanes. Correlation analysis revealed that fruit water loss seemed to be correlated with cuticular wax alkane in the F1 pseudo-testcross population of HJ and ZK. Furthermore, through high-density genetic map and bulk segregant analysis, alkanes and fruit water loss were co-localized to QTL3, resulting in the identification of CER1-1 and CER1-3 as the candidate genes. Heterologous overexpression in Arabidopsis revealed that they were involved in alkane synthesis and reduction of leaf water loss. In addition, coating with C28 alkane could reduce postharvest fruit water loss of six citrus varieties. Collectively, we speculated that cuticular wax alkanes might play an important role in limiting fruit water loss. The study provides new insights into the development of coating agents and breeding of citrus varieties with better storage performance.

Sustainable biomaterials such as natural fibers and biochars have been increasingly used in green infrastructures such as landfill covers for its dual-advantages of climate change mitigation and waste management. The existing studies did not systematically discuss the comparison on how biochar (stable carbon) and fiber (likely degradable), influence plant growth and water retention abilities in unsaturated soils. Also, the effect of photochemistry in the amended soils has rarely been investigated. This study addresses the limitations of previous investigations by exploring plant parameters such as photochemical yield, stomatal conductance, root area index, and unsaturated soil hydraulic parameters, including soil water retention curves (SWRC) of amended soils. Pot experiments were conducted in an environmentally controlled greenhouse. Two biochars from different plant-based feedstocks (Eichhornia crassipes, Prosopis juliflora) and one natural fiber (coir pith fiber) were mixed with soil at 5% and 10% application rate (by weight). Grass species of Axonopus compressus was planted to study the effects of different amendment materials and its corresponding plant responses during an applied drought period. The test results show that biochar amended soils increased the shoot growth by up to 100−200%. The stomatal conductance of the grass leaves increased by 54%−101% during the drought period for both biochars and coir amended soil. Furthermore, at low suction, the coir had a high water retention capacity than the biochars, explaining the observed higher stomatal conductance values. Importantly, it was discovered that the plant photochemical quantum yield responses associated with plant wilting was found to vary between 1500 and 1800 kPa for all the soil treatments. The study concludes with a newly developed mathematical expression based on the measurements of plant parameters and soil suction. The new equation could be used to optimize the irrigation frequency in order to apply any informed measures to maintain green infrastructures.

Wilting and decay are the general postharvest problems of fresh-cut cauliflower during marketing. The objectives of this study were; (i) to investigate the product physiological responses on transpiration and respiration rates (TR and RR) under different storage temperatures (1, 5, 10 and 15 °C) and relatively humidity (RH) (60, 76, 86 and 96%), in order to design packages; and, (ii) to evaluate the impact of packaging design (using PeakFresh (PF), poly-propylene (PP), and NatureFlex (NF)) on the quality of fresh-cut cauliflower at 5 °C for 12 days. Based on the physiological responses, two packages were designed; package-1 (20NF; 20% NF + 80% PP) and package-2 (40NF; 40% NF + 60% PP), while PF (100% PF) and PP (100% PP) served as control. Mathematical model adequately predicted respiration rates as a function of storage time and fitted to the experimental data (R2 = 0.98). The RR of fresh-cut cauliflower was significantly higher than that of the uncut cauliflower and was within the range of 120 and 77.5 mg/kg.h at 5 °C for fresh-cut and uncut cauliflower, respectively. Transpiration rate for fresh-cut cauliflower was lowest at 96% RH across all storage temperatures (p ≤ 0.05). Optimal package was achieved as a function of fresh-cut cauliflower physiological responses. At the end of storage day 12 at 5 °C, optimized 20NF package had the best performance compared to other packages; gas composition was within the range of 5% O2 and 10% CO2, with 0% in-package water vapour condensation but at expense of 7% weight loss.

The relation between bacteria numbers in vase water and vase life of gerbera cut flowers has recently been challenged because of reported negative effects of bactericidal compounds. This relation is investigated using two types of experiments that do not rely on antimicrobial compounds. The first type controls vase water temperature (4, 15, 22 or 28 °C) independently from air temperature (15, 22 or 28 °C) to investigate whether fresh weight behavior for two mini gerbera cultivars (‘Okidoki’ and ‘Kimsey’) is affected by bacterial growth and leaking of soluble sugars in the vase water, or by senescence of the flower head. Fresh weight loss, when compared at constant water temperatures, was higher at higher air temperatures. At higher water temperatures and constant air temperatures fresh weight loss was not higher, although bacterial levels were high enough to expect water uptake issues. Also sugar consumption in the vase water depended on water temperature. This indicates that senescence was the main reason for the decline in fresh weight for these flowers, not bacterial growth. The second type of experiments was based on adding predetermined levels of bacteria (0, 103 or 105 CFU mL−1) and sugars (0.1% glucose or 0.2% sucrose) into vase water of flowers of three large-bloomed (‘Carambole’, ‘Candela’ and ‘Iceberg’) cultivars harvested with closed stem-ends and had their scapes sterilized before the start of vase life. When bacteria were added varying types of responses were observed. ‘Carambole’ flowers showed lower water uptake and lower transpiration and, early scape bending. Petal wilting was observed for ‘Candela’ flowers. ‘Carambole’ flowers showed higher scape sugar leakage levels in the vase water while ‘Candela’ flowers had higher scape firmness. ‘Iceberg’ flowers were also affected by bacteria, resulting in early scape bending, although sugar levels in the vase water were low. Furthermore, adding sucrose and/or bacteria in the vase water of one ‘Iceberg’ and one ‘Carambole’ flower in the same flask resulted in later scape bending for ‘Iceberg’ flowers compared to having two ‘Carambole’ or two ‘Iceberg’ flowers. The results indicate that bacteria interactions with gerbera flowers depend strongly on genotype.

In the 2015–2016 growing seasons, two novel symptoms were assessed on the crown of trees in orchards and coppices of chestnut groves in Central Italy. The first symptom was flagging of annual shoots with green leaves undergoing sudden wilt and turning brown later in the season. The second symptom consisted of leaves on annual shoots turning yellow before wilting in absence of flagging represented the second symptom. Samples were collected along transects in early summer, late summer and winter, and processed in the laboratory. The flagging symptom was associated in early summer with the presence of C. parasitica in cryptic dried buds on stems from the previous year's growth. The pathogen was also found in dormant buds in winter, suggesting that the infection could take place in summer during the Chinese gall wasp oviposition period. Cryphonectria parasitica was also isolated from abandoned galls in winter supporting the hypothesis that galls are a potential source of inoculum for crown infections. Aetiology of yellowing was not clarified and no fungal taxa were specifically associated with this symptom. Gnomoniopsis castanea, C. parasitica and, in early summer, Colletotrichum acutatum were the most abundant fungal taxa isolated from chestnut shoots and buds.

Field pea (Pisum sativum var. arvense L.) is an important legume crop around the world. It produces grains with high protein content and can improve the amount of available nitrogen in the soil. Aphanomyces root rot (ARR), caused by the soil-borne oomycete Aphanomyces euteiches Drechs. (A. euteiches), is a major threat to pea production in many pea-growing regions including Canada; it can cause severe root damage, wilting, and considerable yield losses under wet soil conditions. Traditional disease management strategies, such as crop rotations and seed treatments, cannot fully prevent ARR under conditions conducive for the disease, due to the longevity of the pathogen oospores, which can infect field pea plants at any growth stage. The development of pea cultivars with partial resistance or tolerance to ARR may be a promising approach to analyze the variability and physiologic specialization of A. euteiches in field pea and to improve the management of this disease. As such, the detection of quantitative trait loci (QTL) for resistance is essential to field pea-breeding programs. In this paper, the pathogenic characteristics of A. euteiches are reviewed along with various ARR management strategies and the QTL associated with partial resistance to ARR. Keywords: Field pea, Aphanomyces euteiches, Root rot, Pathogenicity variability, Quantitative trait loci

Charcoal rot caused by the fungal pathogen Macrophomina phaseolina is an important disease of soybean and the use of resistant cultivars is recommended to manage the disease. Since symptoms, including leaf wilt, typically occur as soybeans reach maturity, screening varieties for tolerance to charcoal rot can be time-consuming, requiring nearly an entire growing season. In this study, soybean seedlings (V1) were exposed to a culture filtrate of M. phaseolina containing toxin(s) produced by the fungal pathogen. The effect on the seedlings was measured with hyperspectral spectroscopy on leaves. Two spectrometers integrated with a fiber optic light source and a 6.35 mm diameter probe yielding 480–850 nm and 900–2400 nm ranges after preprocessing were used. The spectra of the untreated plants measured at 0 h, 4 h, 8 h, 12 h, and 24 h post-exposure to the fungal extract were nearly indistinguishable. In contrast, the toxin-treated plants had significantly different spectra from the untreated plants at each of the 4 h, 8 h, 12 h, and 24 h measurements. Reflectance increased in the NIR (900–2400 nm) region with extended exposure to the fungal extract. This change was most noticeable in the 1450 nm and 1940 nm wavebands. Across the spectra, the 24 h reflectance was significantly higher than that of 12 h, which was significantly higher than those of 8 h, 4 h, and 0 h. Jeffries-Matusita (JM) distance, quantifying class separability, was used as a feature selection method and the 24 h measurement had the highest JM distance values, which indicated good separability. Based on JM Distance the most sensitive wavebands were in the regions of 1370–2400 nm. A ratio of the reflectance at 0 h to reflectance at the other times for each of the wavebands was calculated. The ratio curves had two noticeable troughs centered on 1450 nm and 1940 nm, with respective ratios of 0.47 and 0.32 for the 24 h measurement. The 1940 nm ratio at 24 h was proposed as a relative measure of charcoal rot susceptibility of soybean varieties. A ratio of 1.0 indicated no susceptibility with lower ratios indicating greater susceptibility to charcoal rot toxin(s). This study has implications in terms of developing tools to screen for soybean varieties tolerant to charcoal rot and potentially for other biotic or abiotic factors that induce foliar wilting.

Endophytic actinomycetes were isolated from 6 different plants collected from Uttarakhand, India. Actinomycetes isolates were screened for their herbicidal activity against Parthenium hysterophorus, Ageratum conyzoides and Bidens biternata. These isolates belong to the seven different genera. None of the isolate showed herbicidal activity on SCN agar plates. Therefore, direct fermentation method was used for the phytotoxin production in the submerged culture to study the herbicidal activity against different test weeds. The significant differences were observed in the production of phytoxin in SCN and GS medium. In the case of Ageratum conyzoides (billygoat weed), the culture filtrate of Nocardiodes sp. 1, Nocardiodes sp.2 and Actinomadura sp. showed 60% reduction in seed germination. However, culture filtrate of endophytic actinomycetes was ineffective on seed of Bidens biternata in the pre-emergence condition. In Parthenium hysterophorus, the highest seed germination reduction was observed with the culture filtrate (in SCN) of Nocardiodes sp.1 (80%). While in GS medium, maximum inhibition was observed in culture filtrate of Saccharopolyspora sp. (80%). The culture filtrates exhibited phytotoxic activity towards the germinated seedlings of Ageratum conyzoides, Bidens biternata, and Parthenium hysterophorus showing effects like leaf curling, wilting and burning. In post-emergence condition, reduction in shoot-root length was observed with the culture filtrate of Actinomadura sp.1, Nocardiodes sp.1, Streptomyces sp.1, Saccharopolyspora sp. and Microbispora sp. These findings suggest that endophytic actinomycetes are rich source of herbicidal metabolites. Further studies are required to isolate, purify and structure elucidation of the metabolites. Keywords: Endophytes, Weeds, Herbicidal activity, Actinomycetes, Fermentation

The objective of this study was to evaluate the effect of dry matter (DM) concentration and the use of lactic acid bacteria (LAB) inoculant on the protein value of grass silages. Grass samples containing 170 g DM/kg fresh material were wilted to different DM concentrations (310, 390, 420, 470, 530, 580, 600 g/kg fresh material) before ensiling. Half of the grass material at respective DM was treated with LAB, the other half remained untreated (control, CON). Ruminal degradation of organic matter (OM) and crude protein (CP) was determined using the in situ technique. For this, silage samples were incubated for 2, 4, 8, 16, 24, 48 and 72 h. Rumen undegraded CP (RUCP) was derived from in situ CP degradation. Microbial CP (MCP) synthesis was assumed to be 181 g per kg fermented OM. Post-ruminal CP (prCP) was defined as the sum of RUCP and MCP. Effective prCP in situ (prCPk in situ) was calculated for passage rates (k) of 0.02, 0.04 and 0.06/h. In addition, the modified Hohenheim gas test (modHGT) was used to determine effective prCP in vitro (prCPk in vitro) for the same passage rates. The DM linearly increased prCPk in situ in CON (P

Bacterial wilt disease caused by Ralstonia solanacearum affects a wide variety of crops, including tomatoes. Novel natural products and organisms offer opportunities for innovation in agroindustry as an alternative way to pest and pathogen controls. Gluconacetobacter diazotrophicus Pal5 (Gd) belongs to PGPBEs (Plant-Growth-Promoting Bacterial Endophytes), which facilitate plant growth via phytostimulation, biofertilization and biocontrol. In this study Rio Grande tomato seedlings were inoculated with Gd to test its ability to colonize them and its protective potential against the phytopathogen Ralstonia solanacearum A21 (Rso). Gd root and stem colonization of tomato seedlings were determined. Stem height was markedly affected by the inoculation with Gd after 80 dpi and a set of biochemical and anatomical structural changes in root, stem and leaves were triggered. The resistance mechanisms elicited in the plant after inoculation with the endophytic bacteria involved reinforcement of the cell walls in the root vascular cylinder and stem vascular bundles, with the presence of an augmented number of contact cells with dense cellular content, probably pectins, lignin and tannins. Roots and stems presented thicker and more lignified xylem vessel walls. These plants showed statistically significant differences with mock inoculated plants in several quantitative variables, such as area of the xylem vessels in root and stem. Biocontrol assays without Gd showed wilting at 9 dpi with Rso. Histological analysis showed bacteria cells filled xylem vessels and dispersal through tissue degradation. In contrast, plants with Gd remained asymptomatic and phytopathogen colonization was observed to a lesser extent in the stem and root. Anatomical changes primed by Gd were enhanced upon Rso infection and the tyloses process appeared. Therefore, Gd primes the resistance mechanism in Rio Grande tomato plants significantly reducing bacterial wilt caused by Rso.

Reduction of soil moisture by plant root-water uptake could improve soil aeration for microbial aerobic methane oxidation (MAMO) in a landfill cover, but excessive soil moisture removal could suppress microbial activity due to water shortage. Existing models ignore the coupled microbe-vegetation interaction. It is thus not known whether the presence of plants is beneficial or adverse to MAMO. This study proposes a newly-improved theoretical model that couples the effects of root-water uptake and microbial activity for capturing water-gas flow and MAMO in unsaturated soils. Parametric studies are conducted to investigate the effects of root characteristics and transpiration rate on MAMO efficiency. Uniform, parabolic, exponential and triangular root architectures are considered. Ignoring the effects of water shortage on microbe over-predicts the MAMO efficiency significantly, especially for plants with traits that give high root-water uptake ability (i.e., uniformly-rooted and long root length). The effects of plants on MAMO efficiency depends on the initial soil moisture strongly. If the soil is too dry (i.e., close to the permanent wilting point), plant-water uptake, with any root architecture considered, would reduce MAMO efficiency as further soil water removal by plants suppresses microbial activity. Plants with exponential or triangular root architectures could preserve 10% higher MAMO than the other two cases. These two architectures are more capable of minimizing the adverse effects of root-water uptake due to microbial water shortage. This implies that high-water-demand plants such as those with long root length and with uniform or parabolic root architectures require more frequent irrigation to prevent from excessive reduction of MAMO efficiency.

Recent climate effects include severe fluctuation and an increasing probability of extreme meteorological events, such as seasonal and annual drought, the succession between typhoons and summer drought, between low temperature and winter drying, and even the association between high tide and high temperatures. We studied the wilting of Japanese black pine ( Pinus thunbergii Parl.) by investigating the age, site properties and injury status of wilted trees. The water and energy imbalances of wilted trees were determined by measuring the imaging temperature and anthocyanin content and by performing a meteorological analysis. We found a heavy rainfall after a successive normal climate induced the lush growth and secondary height growth of P. thunbergii , which is sensitive to winter drying injury. Pines wilted because of the internal water and energy imbalance due to a sudden change of precipitation and cold injury, especially pine trees growing at unfavorable site conditions. In Northeast Asia and along the coast of China, such extreme changes of precipitation are not infrequent.

The dried root of Rheum tanguticum plays an important role in formulations and prescriptions in traditional Chinese medicine and Kampo medicine. Due to over-exploitation, R. tanguticum resources have decreased sharply in recent years. The main objective of our investigation (a 3-year field experiment) was to explore the effect of different levels of phosphorus (superphosphate) and potassium (potassium sulfate) fertilizer on the biomass (root fresh weight, root increment, and root dry weight), yield, dry matter content, and anthraquinone content of this plant at different harvesting stages (green stage, growth stage, and wilting stage) under alpine conditions. The root fresh weight and root dry weight increased significantly at the wilting stage following treatment with 90 kg P2O5/ha (100% and 59%, respectively) in 2016 and 75 kg K2O/ha (43% and 41%, respectively) in 2015 compared to the control. The yield of root dry weight obtained from three-year-old R. tanguticum plants was 9200 kg/ha when 90 kg P2O5/ha of phosphorus fertilizer was applied, and 10,400 kg/ha when 75 kg K2O/ha of potassium fertilizer was applied. This yield reached a maximum at the wilting stage. The anthraquinone content of two-year-old R. tanguticum plants had already reached the standard level of the Chinese Pharmacopoeia; however, three-year-old plants had double the anthraquinone content of two-year-old plants. Phosphorus and potassium fertilizers had no obvious influence on the anthraquinone content of R. tanguticum at the same harvesting stage.

Root rot is a major disease of strawberry (Fragaria × ananassa cv. Duchesne) worldwide affecting production and leading to huge economic losses. In 2018 and 2019, strawberry plants displaying root rot symptoms accompanied by plant wilting were observed on commercial farms in Beijing, China. A fungus with the general morphological characters of Neopestalotiopsis was consistently isolated from necrotic lesions in symptomatic roots. Eight representative isolates were selected for further studies. Based on morphological characters and phylogenetic analyses of the combined internal transcribed spacer (ITS) region, partial sequences of the β-tubulin gene (tub2) and the transcription elongation factor 1-α (tef1), all isolates were identified as Neopestalotiopsis rosae. Pathogenicity test showed that N. rosae can produce wilt and root rot symptoms on strawberry plants. Therefore, N. rosae was recognized as the causal agent of root rot of strawberry. This is the first report that discusses the role of N. rosae in causing root rot disease on strawberries in China.

The three pre-ensiling treatments dry matter (DM) concentration, wilting intensity and sucrose addition have recently been shown to affect the chemical composition of lucerne (Medicago sativa L.) silages (LS) with highest true protein preservation and improved fermentation quality when lucerne was wilted with high intensity to 35% DM concentration and ensiled with the addition of sucrose. Provided that ruminants prefer these LS to those produced under other pre-ensiling conditions, an improved provision of dietary energy and nutrients may be achieved. However, information on how such pre-ensiling treatments influence the feed choice and DM intake (DMI) of ruminants is lacking and thus, feed choice trials with ten Saanen-type wethers were conducted. The LS were tested in two separate trials split by the factor sucrose addition. In both trials, the animals first passed an adaptation period receiving each differently pre-treated LS (n = 4) and lucerne hay that served as a control for one day to gain forage-specific post-ingestive responses. Subsequently, each possible two-way combination of forages was offered to the animals to determine the forage preference, i.e. 30-min and 3-h DMI. The DM concentration affected the feed intakes at both time points with greater preference for 35% DM LS than for 25% DM LS and a higher consumption was observed for sucrose-treated LS than for untreated LS when related to control lucerne hay. In contrast, wilting intensity showed no influence on DMI. The higher intake of high DM or sucrose-treated LS was likely related to the superior silage quality as indicated by high negative correlations of DMI and non-protein nitrogen, ammonia-nitrogen, acetic acid, butyric acid and gamma-aminobutyric acid concentrations.

Ralstonia solanacearum species complex strains are the causative agents for wilting diseases of many plants, including the economically important brown rot of potato. We developed a high-throughput virulence screen that is implemented in 96-well microtiter plates using seedlings grown in soft water agar to save space, effort, and resources. Nicotiana glutinosa was determined to be the most effective host for this assay, and we confirmed bacterial growth and systemic spread in inoculated seedlings. In our assay, N. glutinosa seeds were sown quickly and easily on top of individual water agar wells of a 96-well plate by pipetting out desired number of seeds in an aqueous suspension. They were inoculated on the same day by first touching a bacterial colony with an autoclaved toothpick and then stabbing the toothpick into the center of the water agar well. Such inoculation method resulted in inocula above a threshold of 2 × 10 4 CFU per well achieving consistent virulence results and enabling reduction of inoculum preparation efforts to facilitate high-throughput screening. Our assay is suitable for forward genetic screening of a large number of strains, isolates or mutants for disease symptoms under both cool (20 °C) and warm (28 °C) temperature conditions before detailed studies can be narrowed down to a manageable number of desired candidates. Our virulence screen method provides a valuable tool for future work in understanding genetics of virulence of Rssc , especially cool virulence of the highly regulated race 3 biovar 2 group of R. solanacearum, leading toward development of effective control strategies.

Pulsed light (PL) is an emerging technology with potential applications in food processing. This study investigated the impact of PL treatment on the viability of Cryptosporidium parvum oocysts inoculated onto cilantro, mesclun lettuce, spinach, and tomatoes. A light with pulses at wavelengths of 180–1100 nm, generated at 3 pulses/s with a pulse width of 360 μs was used. Samples were treated for 0, 10, 45, and 90 s at a working distance of 40 cm. Oocyst viability was determined using an HCT-8 cell culture infectivity assay. The maximum log reductions (log genomic copies) achieved on cilantro, mesclun lettuce, spinach, and tomato were 2.4, 4.3, 2.5, and 2.2, respectively. Significant changes in color values (CIE L*, a*, b*) were not observed in leafy greens or herbs; however, wilting was observed in samples treated longer than 10s. Significant change in the b* value for tomato treated for 90 s was observed. Pulsed light can reduce the infectivity of C. parvum oocysts on cilantro, mesclun, lettuce, spinach, and tomato and with further optimization could have potential applications in post-harvest processing of these commodities.

Nut production by the European sweet chestnut (Castanea sativa Mill.) in grafted orchards is under threat of increased drought stress associated with current global warming. To explore whether drought tolerance in C. sativa could be improved using drought tolerant scions and rootstocks, trees from humid (H) and xeric (X) populations in Spain were used to generate intra-family (H/H and X/X) and reciprocal inter-location (X/H and H/X) grafts. We studied the effects of the (i) scion, (ii) rootstock and (iii) the grafting itself as a wounding stress on the vegetative budbreak, secondary growth and drought tolerance of C. sativa trees. Drought tolerance was assessed by measuring leaf gas exchange, chlorophyll fluorescence, water status and leaf wilting two weeks after water deprivation. Hormone (ABA, SA, JA and JA-Ile) and proline quantification in tree leaves and fine roots were assessed, as well as tree and scion mortality. Rootstocks and scions of xeric origin induced earlier flushing and improved drought tolerance of scions and rootstocks of humid origin. Tree mortality after drought was 57 % lower in H/X than in H/H trees, and scion loss after drought was 47 % lower in H/X than in X/H trees. The ‘grafting’ (i.e., wounding) effect delayed vegetative budbreak and reduced secondary growth of trees but did not predispose trees to drought. We report for the first time differences in hormone and proline content in leaves and fine roots of chestnut trees of humid and xeric origins exposed to drought. The results suggest the use of scions and rootstocks from xeric areas to improve drought tolerance in chestnut.

Drought modifies the endogenous hormonal status, which is involved in the regulation of stress responses and tolerance. This study aimed to characterize the drought-responsive hormone-mediated regulation of stress responses based on the time-course of drought intensity. Alterations in H2O2, Ca2+ and their signaling genes with decreasing leaf water potential (Ψw) were interpreted as being linked to the endogenous hormonal level. Drought responses in relation to SA and ABA balance represented two distinct phases. The early phase, during the first 6 days when the Ψw was greater than -0.78 MPa, was characterized by a rapid decrease in photosynthetic activity with a progressive accumulation of H2O2 and Ca2+ in the strong correlation with the increases in both SA and ABA level. The late phase, days 6–14, was distinguished by ABA-mediated stress symptomatic responses (e.g., the maintenance of the depressed photosynthesis with severe leaf wilting) with highly enhanced expression of ABA-related genes (NCED3 and MYC2) and concomitant depression in the SA level and SA-related genes (ICS1 and NPR1). The regression analysis revealed that both SA and ABA levels as being positively correlated with Ca2+ and H2O2 were closely related to the depression of photosynthesis for the early phase (days 0–6), whereas the correlations were significant only with ABA for the whole period of drought (days 0–14). These results indicate that SA-stimulated H2O2 accumulation and SA responses during the early drought phase are part of upstream H2O2-stimulated ABA accumulation, which causes ABA signaling and responses, leading to severe drought symptoms during the late phase.

Drought leading to water deficit stress is known to reduce performance of galling insects. The shoot tip-galling fly Parafreutreta regalis has been released for biological control of Cape-ivy (Delairea odorata) in California. Lack of moisture during the dry season causes wilting of Cape-ivy shoots, and subsequent reduced host quantity and quality could influence the fly’s ability to multiply and establish. We imposed water deficit stress on potted Cape-ivy plants, then measured the plant’s and insect’s response to water deficit compared to fully-watered plants. Water deficit stress was imposed during female oviposition (short-term), gall development (long-term), or full insect life cycle (long-term). Plants subjected to long-term water deficit showed declines in shoot growth, leaf area, and total biomass. In choice tests, 72% fewer galls were found on water deficit stressed plants, but there was no difference in the numbers of insects per gall. In no-choice tests, long-term water deficit reduced the number and size of galls by up to 51% and 39%, respectively, and puparia inside the galls were up to 35% smaller. Long-term water deficit also increased the time required for the insect to complete its life cycle (egg to adult) by about 10 days, and up to 80% fewer adults emerged, decreasing the fly’s rate of increase by up to five-fold. Our study shows that P. regalis will oviposit and develop successfully on water deficit-stressed plants, but declines in female preference, insect development and abundance could inhibit fly field establishment and/or population growth under climatic drought conditions.

Our previous report indicated that tomato (Solanum lycopersicum) fruit of two contrasting varieties in the chilling tolerance showed the opposite expression pattern of a mitochondrial small heat shock protein (M-sHSP23.8) gene after chilling stress. Thus, the fruit of the relatively tolerant variety Micro-Tom strongly accumulated M-sHSP23.8 transcripts while the susceptible var. Minitomato fruit did not. To test whether M-sHSP23.8 is involved in tomato fruit protection mechanisms against chilling stress, Minitomato fruit overexpressing M-sHSP23.8 (OE23.8) and knockdown Micro-Tom fruit with reduced levels of M-sHSP23.8 (amiR23.8) were developed. After chilling treatment, most of the amiR23.8 fruit failed to ripen normally, showed wilting and skin wrinkles, partial discoloration, and did not reach full red color. On the contrary, these chilling injury symptoms were significantly diminished in OE23.8 fruit, showing less visible deterioration after chilling. Fruit of OE23.8 and amiR23.8 showed opposite patterns of water loss, electrolyte leakage, and expression of the tomato catalase 1 gene compared to control fruit. Membrane lipidome profile evidenced that amiR23.8 fruit showed differential adjustment of extraplastidic and plastidic lipids and variations in the lipid remodeling compared to control fruit, suggesting alterations in the membrane integrity. The high sensitivity of Micro-Tom amiR23.8 fruit and the better performance of Minitomato OE23.8 fruit to chilling treatment indicate that sHSP23.8 may be crucial in the chilling stress tolerance in tomato fruit.

Drought is one of the complex abiotic phenomena that limit wheat production. Improving drought tolerance at the seedling stage is very important as it is a critical stage affecting the subsequent growth stages. In this study, a population consisted of 138 diverse spring wheat genotypes was used to identify the most drought tolerant genotypes and genomic regions controlling drought tolerance at the seedling stage. Three morphological traits were scored: seedling length, days to wilting, and leaf wilting. All genotypes had a high genetic variation in all the seedling traits scored in this study. Moreover, high significant phenotypic and genotypic correlations were found among these traits. Heritability estimates for these morphological traits ranged from 0.59 to 0.86. Nine genotypes from different countries were identified as drought-tolerant genotypes. The genome-wide association study (GWAS) was performed on the population using 407 Diversity Arrays Technology (DArT) markers which were distributed across 21 wheat chromosomes. The results of GWAS revealed 104 significant QTL controlling drought tolerance and susceptibility in wheat. A set of 12 markers was found to be associated with more than one trait. Out of the 12 markers, the WPT-2356 was found to be associated with drought susceptibility in all traits scored in this study. The gene annotation analysis revealed that this marker fell within TraesCS7B02G438200 gene model which encodes to UBA-like superfamily protein (a negative drought regulator). Moreover, four significant DArT markers WPT-6668, WPT-8460, WPT-8124, and WPT-4196 found in this study were previously reported with their association with drought tolerance and susceptibly at wheat seedling stage. The nine genotypes can be used as candidate parents to improve drought tolerance in spring wheat. Moreover, promising validated markers can be used for marker-assisted selection to genetically improve drought tolerance through a breeding program.

Quantitative detection of pathogen DNA load is a crucial aspect in development of disease management strategies and breeding programs. In recent years, there have been several reports where formae speciales specific intergenic spacer (IGS) sequence based markers have been used for quantification of pathogen DNA in different plant and soil samples, through quantitative real-time PCR (qPCR). In the present study, we have utilized an IGS based marker, ISR 52, to detect and quantify Fusarium oxysporum f.sp. ciceris (Foc) DNA, using both conventional PCR and qPCR, in chickpea genotypes which contrast for resistance to Fusarium wilt. Our study reveals that the Foc DNA load was found to be significantly higher in the early wilting genotypes as compared to the wilt resistant genotypes. Late wilting genotype showed a spike in pathogen DNA load in later stage of plant growth. Phenotypic observation of disease progression in combination with qPCR data validated that the pathogen undergoes incubation period before manifestation of symptoms. The above observations provide evidence about the differential dynamics of pathogen build up inside different hosts during different time periods and probable reason for the earliness, lateness and resistance in wilting like traits in these genotypes.

Certain fungal endophytes improve plant resistance to biotic stresses in forest trees. In this study, three stem fungal endophytes belonging to classes Cystobasidiomycetes, Eurotiomycetes and Dothideomycetes were selected from 210 isolates for their potential as enhancers of Ulmus minor resistance to Ophiostoma novo-ulmi. We evaluated phenotypic traits of these endophytes that could be beneficial for inhibiting O. novo-ulmi in the host plant. Under in vitro conditions, the Dothideomycetous isolate YCB36 strongly inhibited O. novo-ulmi growth, released antipathogenic VOCs, chitinases and siderophores, and overlapped with the pathogen in nutrient utilization patterns. These functional traits could explain the 40% reduction in leaf wilting due to O. novo-ulmi in elm trees pre-inoculated with this endophyte. Ulmus minor trees inoculated with this endophyte showed increased leaf stomatal conductance and higher concentrations of flavonoids and total phenolic compounds in xylem tissues, suggesting induction of defence metabolism.

Dragon fruit undergoes rapid senescence resulting in yellowing and wilting of bracts during storage. This study identified the synergistic effect of gibberellic acid (GA3) or methyl jasmonate (MeJA) dipping combined with chitosan- and κ-carrageenan-based composite coating on the postharvest quality of dragon fruit during storage at 10 °C, 90–95 % RH. Coating with 1.0 % chitosan and 0.2 % κ-carrageenan- based composite decreased the fruit weight loss to lower than 5 % after 30 days of storage and had a positive effect on reducing disease infection. Fruit dipped in 50 mg L−1 GA3 or 0.1 mM MeJA for 5 min was maintained a better bract quality compared to the control. The treatment of 1.0 % chitosan and 0.2 % κ-carrageenan- based composite combined with 50 mg L−1 GA3 or 0.1 mM MeJA pretreatment retained a higher chlorophyll content in bracts (47.98 and 48.43 mg 100 g−1 DW, respectively) compared to the coating alone with 1.0 % chitosan and 0.2 % κ-carrageenan- based composite (45.46 mg 100 g−1 DW) via inhibiting the activities of chlorophyll-degrading enzymes. However, bract colour was maintained in all coating treatments compared to the control. The composite coating alone or pretreatment with MeJA significantly maintained titratable acidity, while the combination of GA3 or MeJA pretreatment and coating retained total soluble solids and increased vitamin C content. No treatment was found to have a significant effect on fruit firmness, ethanol and acetaldehyde, total phenolic content, antioxidant activity, and disease symptoms. We concluded that the chitosan- and κ-carrageenan-based composite coating was crucial for maintaining the freshness and bract colour, and in combination with GA3 or MeJA pretreatment was better in retaining chlorophyll content and dragon fruit eating quality.

Although the physiological states of intact and cut flowers are expected to be significantly different, the floral scent emissions of these two conditions has yet to be compared. We compared the scent emissions from intact and cut flowers using carnation (Dianthus caryophyllus L.) cultivars with two different scent-types—a fruity scent based on benzenoid methyl benzoate and a spicy scent based on eugenol. Methyl benzoate or eugenol, which were the principal scent components, always had the highest percentage (> 30 %) in both intact and cut flowers from flower opening to wilting. The total emissions from intact flowers remained at a similar level for approximately 6 days after flower opening, and then gradually decreased with flower senescence. The total emissions from cut flowers were highest on the day of flower opening and then decreased more rapidly than emissions from intact flowers. Furthermore, the duration of noticeable scent of cut flowers was estimated to be shorter than that of intact flowers. The expression of various scent emission-related genes encoding floral volatile benzenoid/phenylpropanoid biosynthesis enzymes, adenosine triphosphate-binding cassette transporters, and MYB transcription factors increased with flower opening and were accompanied by scent emissions. However, the expressions of most of these genes were not affected by cutting, suggesting that the decrease in scent emissions from cut flowers is unlikely due to changes in gene expression. Recently, we reported that cutting accelerates the decrease in sugar content and increases ethylene production in carnation petals, resulting in hastened flower senescence. Therefore, the rapid decrease in scent emissions from cut flowers may be due to a decrease in sugars, which are substrates for the scent components.

Cut roses (Rosa hybrida L.) have been classified as ethylene-sensitive, but the nature of the ethylene sensitivity changes in these flowers has not been well characterized. In the present study, the relationships between vase life, ethylene sensitivity, and expression of ethylene biosynthetic genes were determined in 33 cultivars. Despite the same growing season and identical postharvest environments, the vase life of cultivars ranged from 5.5 to 15.5 d. Ethylene primarily accelerated petal wilting, which is the main factor shortening the longevity in long vase life cultivars. qRT-PCR analysis revealed that among five ethylene synthesis genes, RhACO1 showed the most distinct expression patterns in response to ethylene. ACS genes were differentially expressed in response to ethylene, and only RhACS2 and RhACS4 are induced by ethylene and during flower senescence. Correlation analysis revealed that the major factors that terminate vase life vary depending on flower sensitivity to ethylene. The vase life of ethylene-sensitive cultivars was strongly related to RhACO1 transcript level, which was induced by ethylene exposure. In contrast, the vase life of ethylene-insensitive cultivars was mostly reduced due to an early failure of water relations, as a consequence of the decreased hydraulic conductance of stems and water loss via transpiration. The current study revealed that postharvest treatments to improve the vase life should be differently applied based on the ethylene sensitivity of each cultivar.

It was established that the main causes of mass diseases of tomato in covered ground in Ukraine are agents of bacterial black spotting, bacterial speck and in open ground are agent of bacterial cancer of tomato plants. Typical symptoms of diseases are wilting and die-off of young plants, blackening of fiber vascular bundles, black spotting of leaves and fruits, and fruit stem rot. It was studied morphological and cultural, as well as physiological and biochemical properties of the selected strains of the agents of tomato bacterial diseases. We recommended biological preparations Phytocide and Phytohelp based on the bacteria Bacillus subtilis , to restrict the development of the agents of bacterial black spotting Xanthomonas vesicatoria and bacterial cancer Clavibacter michiganensis subsp. michiganensis .

Direct seeding is an effective approach for plant re-establishment and revegetation of post-mining areas. However, germination of seeds is influenced by environmental stressors such as soil water conditions and salinity, eventually affecting revegetation success. In this study, we conducted laboratory experiments to evaluate the effect of water stress and salinity on the germination of Atriplex halimus seeds. We exposed seeds to various solutions of NaCl and Polyethylen Glycol (PEG) ranging from soil saturation (0 MPa) to permanent wilting point (−1.5 MPa). We measured the germinability and mean germination time to quantify seed germination. Based on the measured germination data, we estimated the parameters of the hydrotime model, which is a critical tool to predict timing and success of seed emergence. At an osmotic potential of −1.5 MPa, 31% or 3% of the seeds germinated when exposed to PEG or NaCl solution, respectively. This indicates that Atriplex halimus seeds are highly tolerant to water stress, but less tolerant to salinity stress. The results of this study suggest that direct seeding of Atriplex halimus may be an effective path for revegetation of post-mining landscapes where salinity and water stress are predominant features of the environment.

Superabsorbent polymers (SAPs) as soil moisture conditioners have been increasingly used in agriculture, but conflicting results were reported regarding the effects of SAPs on crop growth. In this study, both laboratory cultivation and analysis were conducted to investigate the effects of different SAPs on the growth and physiology of crops under water-saving agricultural practices. Maize ( Zea mays L.) seedlings were cultivated using distilled water or three different SAP hydrogels, sodium polyacrylate (SP), potassium polyacrylate (PP), and sodium polyacrylate embedded with phosphate rock powder (SPP), as growth media. Growth characteristics of the model plant and damage were assessed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that both the SP and PP treatments had pronounced negative effect on the hydrogels of growth of maize seedlings. The SPP treatment appeared to facilitate the stem-leaf growth and had no obvious adverse effect on root growth. All the three hydrogel treatments caused varying degrees of damage to the organizational structure and cellular morphology of the roots, with the SP and PP treatments causing the most severe damage; the membrane system of root cells was damaged by both SP and PP treatments. An excessive accumulation of sodium and reduction of calcium occurred in the roots may be responsible for the observed damage to the cell membrane system, which, in turn, may have promoted the wilting of the cells.

Commercial cucurbits are commonly grafted onto interspecific Cucurbita hybrid rootstocks. The unproven paradigm is that hybrid rootstocks are more vigorous, resulting in better yields and high-level resistance. The objective of this study was to test the above hypothesis by comparing the performance of parental lines to that of derived F1 hybrids as non-grafted Cucurbita accessions and as grafted melons, in experiments conducted in the greenhouse and in the field. The response to biotic stress was evaluated in with Rhizoctonia solani inoculated non-grafted Cucurbita parents and hybrids. In four out of the five hybrid–parent sets evaluated, susceptibility of the hybrid to R. solani was reduced or comparable to that of the parents. Grafted melon performance, expressed by plant development index, physiological wilt incidence and fruit yield, was evaluated in the field and in the greenhouse. Three hybrids out of the five tested in the field exhibited lower physiological wilt incidence than their parents. In three parent–hybrid sets, the male parent exhibited the worst rootstock performance and in one case, the male parent exhibited the lowest wilting. Fruit yield of grafted melons was highly correlated to wilt incidence. According to our results, the superiority of the hybrid over its parents and the benefit of the interspecific Cucurbita rootstock are not conclusive and varies among crosses and traits. The pathological, horticultural and economic benefits of this approach should therefore be further tested and reconsidered.

In 2015, red or black-brown necrotic lesions on main or lateral veins associated with the wilting of leaves and dry rot caused by plant pathogenic bacteria were found in tobacco plants in different fields in Shaowu city, Fujian province, China. Two bacteria (FM3 and FM4) were isolated and selected for further tests. Pathogenicity test results showed that all the tested isolates developed typical vein rot symptoms in tobacco 4 days after inoculation and soft rot symptoms in potato tuber, okra, pepper, capsicum, celery, and Chinese cabbage 2 days after inoculation, with the bacterium re-isolated from all the inoculated plants. On the basis of phenotypic properties, maceration characteristics, biochemical tests, Biolog system, and 16S rRNA sequences analysis, isolates FM3 and FM4 were identified as Pectobacterium carotovorum subsp. carotovorum . To our knowledge, this is the first report that the new bacterial vein rot disease in tobacco in Shaowu city, China, was caused by P. carotovorum subsp. carotovorum .