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Pests and environmental factors are normally considered as ones of the most widespread stresses that lead to detrimental effects on crop production and quality. Cytochrome P450s (CYPs) are a large protein family which mediates many physiological activities via the biosynthesis of secondary metabolites and detoxifying pathways. Additionally, by controlling phytohormones and secondary metabolite synthesis and accelerating reactive oxygen species (ROS) scavenging, CYPs have the ability to promote plants' molecular and chemical defense mechanisms, making them significant targets for genetic engineering in order to strengthen plant defense against environmental stresses. In this study, the GmCYP gene was transformed into tobacco (N.tabacum cultivar K326) via Agrobacterium-mediated transformation for the study of transgenic plants' resistance to environmental stresses. Under the drought treatment, transgenic tobacco plants displayed changes in metabolite profiling analysis, such as considerably lower chlorophyll degradation, higher proline accumulation, higher rate of antioxidant (POD) activity, indicating their advanced abiotic stress tolerance phenotype. At the same time, their growth and development characteristics remained unchanged as compared to the wild type. Furthermore, in transgenic tobacco plants, caterpillars showed depleted growth features, such as delayed life cycles, shorter lengths, and lower weights, proving enhanced pest resistance of CYP transgenic plants. Therefore, these findings imply that overexpression of GmCYP impacts drought stress tolerance as well as insect resistance, and this candidate gene has potential for further research in the crop improvement program. [ABSTRACT FROM AUTHOR]

Bacillus thuringiensis (Bt) represents one of the most economical biopesticides to date. It produces toxins with insecticidal activity against many agricultural pests, including members of the genus Spodoptera. However, Bt tolerance leads to inefficiency in biological control. To overcome this problem, discovering the hidden cause(s) for the evolution of insect tolerance against Bt is of great importance. We hypothesized that changes in the gut microbiota due to the frequent application of Bt is one of those hidden causes. To investigate this hypothesis, we studied the effect of Bt Cry1c application on the Spodoptera littoralis larval gut microbiota in both Bt-susceptible and Bt-tolerant populations. The results revealed changes in the diversity and abundance of gut bacterial composition between the susceptible and tolerant populations. A high abundance of Enterococcaceae was detected in the tolerant population. Interestingly, Cry1c tolerance eliminates the bacterial genera Klebsiella and Serratia from the larval midgut. These changes may confirm the mechanism developed by Spodoptera larvae to counteract Bt Cry1c toxicity. Understanding the B. thuringiensis–gut microbiota interaction may help in improving biocontrol strategies against agricultural pests to overcome the evolution of tolerance.

Bacillus thuringiensis (Bt) represents one of the most economical biopesticides to date. It produces toxins with insecticidal activity against many agricultural pests, including members of the genus Spodoptera. However, Bt tolerance leads to inefficiency in biological control. To overcome this problem, discovering the hidden cause(s) for the evolution of insect tolerance against Bt is of great importance. We hypothesized that changes in the gut microbiota due to the frequent application of Bt is one of those hidden causes. To investigate this hypothesis, we studied the effect of Bt Cry1c application on the Spodoptera littoralis larval gut microbiota in both Bt-susceptible and Bt-tolerant populations. The results revealed changes in the diversity and abundance of gut bacterial composition between the susceptible and tolerant populations. A high abundance of Enterococcaceae was detected in the tolerant population. Interestingly, Cry1c tolerance eliminates the bacterial genera Klebsiella and Serratia from the larval midgut. These changes may confirm the mechanism developed by Spodoptera larvae to counteract Bt Cry1c toxicity. Understanding the B. thuringiensis–gut microbiota interaction may help in improving biocontrol strategies against agricultural pests to overcome the evolution of tolerance. [ABSTRACT FROM AUTHOR]

Brown planthopper (Nilaparvata lugens Stal. Homoptera, Delphacidae) is a pest of rice (Oryza sativa L. Cyperales, Poaceae), whose feeding significantly reduced photosynthesis. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) activase (RCA) is a key photosynthetic enzyme. The aim of this study was to examine whether RCA gene of O. sativa (OsRCA) affects photosynthetic efficiency and thereby growth performance of rice infested by brown planthoppers. For this, we conducted experiments in which we overexpressed OsRCA large and small isoforms (oeRCAL and oeRCAS, respectively) and silenced OsRCA (irRCA) in rice. After infestation by brown planthoppers, the photosynthetic rate, plant height and dry weight of overexpressed OsRCA lines were significantly higher than those of wild-type (WT) and irRCA. Initial RuBisCO activity in oeRCAL and oeRCAS was also higher than in WT and irRCA. Overexpression OsRCA alleviated the adverse response of the decrease in the chlorophyll content, maximum photochemical efficiency (Fv/Fm) and photochemical performance index (PIABS). The increase in energy dissipation and quantum yield of energy dissipation in oeRCAL and oeRCAS after infestation by brown planthoppers werer much lower than in WT and irRCA. Thus, we concluded that overexpression of OsRCA, particularly OsRCAS, can alleviate chlorophyll degradation and reduce heat dissipation of photosystem, thereby reducing the degree of photosynthesis damage caused by brown planthoppers infestation. [ABSTRACT FROM AUTHOR]

Thirty sweetpotato (Ipomoea batatas var. batatas) genotypes were evaluated for yield, resistances to weevil or nematode pests, and consumer acceptance across three field trials planted at Pepe‘ekeo, Hawai‘i Island between 2017 to 2020. At harvest, storage roots were graded according to market standards, followed by scoring for damage by sweetpotato weevil (Cylas formicarius elegantulus), rough sweetpotato weevil (Blosyrus asellus), or nematodes; namely root-knot nematode (Meloidogyne spp.) or reniform nematode (Rotylenchus reniformis) in each market class. There were significant differences in marketable yields among accessions when data were analyzed statistically across all three field trials, as well as individually. ‘Regal’ (PI 566650) and ‘Sumor’ (PI 566657) were among the top three highest-yielding genotypes for Trials 1 and 2 (when no insecticides were applied to control weevils), and among the top six highest-yielding genotypes for the joint analysis across three trials. Significant differences among genotypes for combined sweetpotato weevil damage (incidence of sweetpotato weevil alone or incidence of both weevils together) were found in the joint analysis across three trials. ‘Regal’ was among the lowest seven genotypes for combined sweetpotato weevil damage, supporting earlier reports of its moderate resistance to this pest. In addition, two genotypes produced by the World Vegetable Center (Shanhua, Taiwan) (WT-320 and WT-108), were among the lowest genotypes for combined sweetpotato weevil damage, in agreement with earlier reports of their substantial resistance to this pest. Providing access to diverse germplasm will help farmers react to increasing pest pressure, while still allowing for high marketable yields. In addition, breeding and selection for pest resistance could be an important addition to integrated pest management of sweetpotato in Hawai‘i.

Interest in the development of organically grown vegetable crops has risen over the past decades due to consumer preferences. However, most crops that have desirable consumer traits have been bred in conventional growing conditions, and their transfer to an organic setting is challenging. Here, the organically grown Hawaiian pumpkin (Cucurbita moschata) accession 'Shima' was crossed with the conventionally grown Puerto Rican variety 'Taina Dorada' to develop a backcross (BC1) population, where 'Shima' was the recurrent parent. A total of 202 BC1 ('Shima' X F1) progenies were planted in a certified organic field, and twelve traits were evaluated. We used genotype-by-sequencing (GBS) to identify the Quantitative Trait Loci (QTL) associated with insect tolerance along with commercially desirable traits. A total of 1582 single nucleotide polymorphisms (SNPs) were identified, from which 711 SNPs were used to develop a genetic map and perform QTL mapping. Reads associated with significant QTLs were aligned to the publicly available Cucurbita moschata genome and identified several markers linked to genes that have been previously reported to be associated with that trait in other crop systems, such as melon (Cucumis melo L.). This research provides a resource for marker-assisted selection (MAS) e orts in Cucurbita moschata, as well as serving as a model study to improve cultivars that are transitioning from a conventional to an organic setting. [ABSTRACT FROM AUTHOR]

Genetic diversity of cultivated soybean {Glycine max (L.) Merrill} 2n = 40 is very narrow, although includes diversity for many obvious morphological traits. A field experiment was conducted to study characterize of fifteen soybean genotypes on agro-morphological trait basis and to identify genetic diversity using SDS-PAGE, with resistance to defoliating insects, at Sakha Agricultural Research Station, Kafr ElShiekh, Egypt during 2017 and 2018 seasons,. Morphological description was performed with 10 qualitative and 7 quantitative traits and screening for defoliation by cotton leaf worm in the open field. The results exhibited significant differences among the tested fifteen genotypes for all studied characters. Defoliation of test plants by the cotton leaf worm, in the field screenings system showed that genotypes H14 L8, H1 L10S, H1 L10 and H10 L10 recorded the highest rating values of insect resistant to cotton leaf worm with defoliation rating (0.0 – 0.2), whereas, soybean genotype H5 L21 showed the highest insect susceptible and had defoliation rating (3.8) indicating heavy insect feeding, over both seasons. Genotypes H11 L145 and H14L8 recorded the highest values of seed yield/fad., this attributed to the considerable increase in their number of branches/plant, number of pods/plant, and 100-seed weight, in both seasons. This indicates that such genotypes are the promising ones. The protein identification indicated that the pattern was uniform where each genotype was not affected by year or location. The soybean genotypes were different in their banding pattern and each one is characterized by certain proteins with different molecular weight. Cluster analysis based on qualitative morphological characters showed clear separation of genotypes on the basis of their plant growth habit. [ABSTRACT FROM AUTHOR]

Interest in the development of organically grown vegetable crops has risen over the past decades due to consumer preferences. However, most crops that have desirable consumer traits have been bred in conventional growing conditions, and their transfer to an organic setting is challenging. Here, the organically grown Hawaiian pumpkin (Cucurbita moschata) accession ‘Shima’ was crossed with the conventionally grown Puerto Rican variety ‘Taina Dorada’ to develop a backcross (BC1) population, where ‘Shima’ was the recurrent parent. A total of 202 BC1 (‘Shima’ X F1) progenies were planted in a certified organic field, and twelve traits were evaluated. We used genotype-by-sequencing (GBS) to identify the Quantitative Trait Loci (QTL) associated with insect tolerance along with commercially desirable traits. A total of 1582 single nucleotide polymorphisms (SNPs) were identified, from which 711 SNPs were used to develop a genetic map and perform QTL mapping. Reads associated with significant QTLs were aligned to the publicly available Cucurbita moschata genome and identified several markers linked to genes that have been previously reported to be associated with that trait in other crop systems, such as melon (Cucumis melo L.). This research provides a resource for marker-assisted selection (MAS) efforts in Cucurbita moschata, as well as serving as a model study to improve cultivars that are transitioning from a conventional to an organic setting.

This research was carried out to selection of desirable cultivar for organic cultivation of carrot in Korea. The assay of disease resistance, insect tolerance and rate of bolting were investigated on 32 cultivars of genetic resources of carrot. This experiment was carried out at experimental field and greenhouse of Gangneung- Wonju National University. ``PI 223360`` was resistant against powdery mildew. Ten cultivars including ``Oxheart Carrot Heirloom`` were moderately resistant, 22 cultivars including ``Long Impeator #58`` were susceptible to powdery mildew. Although there was no resistant cultivar against black rot and leaf blight, our results showed that several cultivars have moderate resistance. Thirteen cultivars including ``Oxheart Carrot Heirloom`` were having insect (Erythroplusia pyropia) tolerance and ``SA 102`` and ``Scarlet Keeper Carrot Rare`` were susceptible. According to the investigation of bolting, 6 cultivars including ``Hongsim Ouchon Carrot`` were early bolting and 4 cultivars including ``Japanese Imperial Long Carrot`` were moderate bolting. Other cultivars were identified as late bolting. From above results, we confirmed that ``Oxheart Carrot Heirloom`` was suitable cultivar for organic cultivation among 32 genetic resources of carrot.

Abstract: The relationship between susceptibility of different peach cultivars (cvs) to the Mediterranean fruit fly (medfly), Ceratitis capitata, and the volatile composition of ripe fruit of each cv has been investigated, since understanding the fruit-insect interaction mechanism is crucial for developing control strategies for such a pest. Volatile compounds were analyzed by SPME–GC–MS in three cvs highly susceptible to medfly attack (Fair Time, Flaminia, Sicilia Piatta), and in two less susceptible cvs (Percoca Romagnola 7 and Doctor Davis). Among the volatile compounds detected, 88 could be identified. The main differences found in the volatile composition of the cvs, concerned the relative abundance of esters. The least susceptible cvs, above all Percoca Romagnola 7, contained the higher amounts of hexenyl, hexyl, 3-methylbutyl, butyl and 2-methylpropyl esters; among these, some C6 derivatives detected, such as (Z)-3-hexenyl acetate, are known to act as priming agents, enhancing plant defence response to insects. Instead, a lower relative content of methyl esters, such as methyl hexanoate and methyl octanoate, known to act as medfly pheromone and attractant respectively, was found in the least susceptible cvs. [Copyright &y& Elsevier]