Peanut, a major edible oil seed crop globally is predominantly grown under rainfed conditions and suffers yield losses due to drought. Development of drought-tolerant varieties through transgenic technology is a valid approach. Besides superior water relation traits like water mining, intrinsic cellular level tolerance mechanisms are important to sustain the growth under stress. To achieve this objective, the focus of this study was to pyramid drought adaptive traits by overexpressing a stress responsive helicase, PDH45 in the background of a genotype with superior water relations. PCR, Southern, and RT-PCR analyses confirmed stable integration and expression of the PDH45 gene in peanut transgenics. At the end of T₃ generation, eight transgenic events were identified as promising based on stress tolerance and improvement in productivity. Several transgenic lines showed stay-green phenotype and increased chlorophyll stability under stress and reduced chlorophyll retardation under etherel-induced simulated stress conditions. Stress-induced root growth was also substantially higher in the case of transformants. This was reflected in increased WUE (low Δ¹³C) and improved growth rates and productivity. The transgenics showed 17.2 and 26.75 % increase in yield under non-stress and stress conditions over wild type ascertaining the feasibility of trait pyramiding strategy for the development of drought-tolerant peanut.

The amenability and reproducibility of a tissue culture-independent Agrobacterium tumefaciens-mediated transformation strategy was analyzed in field bean and the stability of the transgenes was examined. The protocol involves in planta inoculation of embryo axes of germinating seeds and allowing them to grow into seedlings ex vitro. Transformants were raised using a chimeric Bt gene, cry1AcF, and putative transformants were analyzed by PCR for both cry1AcF as well as the nptII genes. Bioassays against Helicoverpa armigera, the major pod borer, showed that several T 1 plants performed well with 17% of T 1 plants harboring the transgene. Further, enzyme-linked immunosorbent assay (ELISA) and quick dip strip test confirmed the expression of the chimeric Bt toxin. The stability of the transgenes was checked in three generations for integration, expression, and efficacy against the two insects, H. armigera and Spodoptera litura. Southern blot analysis of 10 high expressing plants confirmed the integration of the transgene, whereas single copy integration of the T-DNA in 5 events was also evident. Transcript accumulation of the cry1AcF gene by Northern analysis supported the expression analysis by ELISA. Likewise, Western blot analysis for the NPTII protein further confirmed the transgenic nature of the plants. At the end of the analysis in the T 3 generation, five plants from five T 1 events were selected as promising. Therefore, the study proved not only the amenability of the field bean to the transformation protocol but also the stability of the introduced genes through three generations.

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