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Genetically engineered crop plants for enhanced emission of herbivore-induced plant volatiles (HIPVs) offer great potential in reducing the herbivore load on crops by repelling insect herbivores directly or attracting their natural enemies. Plant volatile organic compounds (VOCs) are also essential for pollination, insect reproduction, allelopathy, and serve as antimicrobial agents. Existing research in this field revolves around the routine chemical ecological experiments like identifying VOCs, HIPVs, and synthetic blends. Therefore, a deeper understanding of the role of enhanced volatile emissions and volatile biosynthetic pathways involved in chemical communication can lead to the development of behavior-based novel pest management strategies and lay the foundation for future research in these approaches. Recent discoveries in identifying and isolating the enzymes and genes associated with the biosynthetic pathways of volatiles have opened new avenues for the genetic engineering of crops. Genetically engineered plants could be developed to release volatiles only with an herbivore attack to conserve plant resources by mimicking a natural defensive strategy for direct repellence and/or recruitment of natural enemies. Crops engineered for sustainable volatile production can also serve as companion plants in the push and pull strategies and modify insect behavior to reduce the pest damage. A crop bioengineered for enhanced repellence of oviposition and increased release of insect pheromone-resembling compounds could benefit pest management programs. Further advanced research under field conditions is required to assess the physiological and ecological consequences, especially to the crop and the environment. [ABSTRACT FROM AUTHOR]

Pigeonpea (Cajanus cajan) production can be affected by the spotted pod borer (Maruca vitrata). Here, we identified biochemical changes in plant parts of pigeonpea after M. vitrata infestation. Two pigeonpea genotypes (AL 1747, moderately resistant; and MN 1, susceptible) were compared for glyoxalase and non-glyoxalase enzyme systems responsible for methylglyoxal (MG) detoxification, γ-glutamylcysteine synthetase (γ-GCS), glutathione-S-transferase (GST) and glutathione content in leaves, flowers and pods under control and insect-infested conditions. MN 1 had major damage due to M. vitrata infestation compared to AL 1747. Lower accumulation of MG in AL 1747 was due to higher activities of enzymes of GSH-dependent (glyoxylase I, glyoxylase II), GSH-independent (glyoxalase III) pathway, and enzyme of non-glyoxalase pathway (methylglyoxal reductase, MGR), which convert MG to lactate. Decreased glyoxylase enzymes and MGR activities inMN1 resulted in higher accumulation of MG. Higher lactate dehydrogenase (LDH) activity in AL 1747 indicates utilisation of MG detoxification pathway. Higher glutathione content in AL 1747 genotype might be responsible for efficient working of MG detoxification pathway under insect infestation. Higher activity of γ-GCS in AL 1747 maintains the glutathione pool, necessary for the functioning of glyoxylase pathway to carry out the detoxification of MG. Higher activities of GST and GPX in AL 1747 might be responsible for detoxification of toxic products that accumulates following insect infestation, and elevated activities of glyoxylase and non-glyoxylase enzyme systems in AL 1747 after infestation might be responsible for reducing reactive cabanoyl stress. Our investigation will help the future development of resistant cultivars. [ABSTRACT FROM AUTHOR]

Development of transgenic crops with stable gene inheritance and expression over generations is important for effective deployment at field level. In present study, T1 plants of pigeonpea cultivars AL15 and AL201 were evaluated for the presence and expression of cry1Ab gene and protection against Maruca pod borer. Cry1Ab protein in transgene carrying T1 plants ranged from 0.72 to 0.87 µg g-1 flower tissue. In vitro insect bioassay demonstrated up to 49.17 and 53.80% loss in larval body weight after four days of infesting T1 transgenic flowers and pods, respectively. Further, no adults emerged from the pupae of larvae fed on transgenic plants 15-537 and 201-344. All T2 progeny plants of 15-537 exhibited cry1Ab presence; likewise, all T3 progeny plants derived from homozygous T2 plant (15-537-5) displayed presence and expression of transgene, thus establishing stable transgene integration in T1 plants, followed by its stable inheritance and expression in T2 and T3 generations. [ABSTRACT FROM AUTHOR]

Antioxidative compounds were quantified from the leaves of nine black gram (Vigna mungo (L.) Hepper) genotypes over a period of two years, for potential whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleryrodidae) resistance. Oviposition preference, nymphal and adult development were evaluated under screen-house conditions. Biochemical analysis revealed that higher per cent increase in the total phenol and o-dihydroxy phenol contents both at 30 and 50 days after sowing was evident in moderately resistant genotypes NDU 5-7 (49.6 and 50.8%, respectively) and KU 99-20 (47.8 and 50.8%, respectively) under whitefly stress conditions as compared to non-stressed plants. Tannin and flavonol contents in leaves increased to varying degrees (up to 11.1 and 7.1%, respectively) in resistant plants after whitefly infestation, indicating that the changes in tannin and flavonol contents were closely associated with the resistance to whitefly. Correlation studies relating leaf content of black gram antioxidative compounds from different genotypes with whitefly population were also worked out. Total phenols (r = -0.71 & -0.88), o- dihydroxy phenols (r = -0.56 & -0.76), flavonols (r = -0.80 & -0.81) and tannins (r= -0.16 & -0.26) showed significant negative correlation with whitefly population (nymphs and adults) suggesting that enhanced level of these biochemicals may contribute to bioprotection of black gram plants against B. tabaci infestation. Comparatively higher level of resistance in genotype NDU 5-7 and KU 99-20 can serve as base for genetic improvement of black gram, focusing on the development of resistant varieties to B. tabaci.