Sorghum bicolor L. Moench cv. SPV462 was transformed with the mtlD gene encoding for mannitol-1-phosphate dehydrogenase from E. coli with an aim to enhance tolerance to water deficit and NaCl stress. Transgene (pCAM mtlD) integration and expression were successfully confirmed by PCR, Southern, RT-PCR and Western analysis. Segregation analysis based on germination of T 0 seed on hygromycin-supplemented medium revealed an expected Mendelian ratio 3:1 in lines 5, 72 and 75. Retention of leaf water content was remarkably higher in transgenic leaf segments when exposed to polyethylene glycol 8000 (-2.0 MPa), as compared to the untransformed controls. Another significant finding is that the transgenics maintained a 1.7 to 2.8 fold higher shoot and root growth, respectively, under NaCl stress (200 mM) when compared to untransformed controls. These results demonstrate that engineering mannitol biosynthetic pathway into sorghum can impart enhanced tolerance to water deficit and salinity.

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Sunflower (Helianthus annuus L.) and maize (Zea mays L.) were chosen as C₃and C₄ crop plants and assessed for the impact of enhanced CO₂ (700 ppm) and its interaction with drought stress in open top chambers (OTCs). The ameliorative effect of higher CO₂ concentration (eCO₂) under drought stress was quantified. It is interesting to note that the C₃ crop responded significantly and positively with eCO₂ under both well-watered and drought stress treatments for root: shoot ratio while C₄ crop showed a better response only with the drought stress environment. Root volume showed a positive significant response with CO₂ concentration enhanced over ambient level and the increment in root volume was 146% and 340% in sunflower and maize crops, respectively. The leaf water potential, stomatal conductance and transpiration showed a decreasing trend in both the crops with drought stress and eCO2 showed an ameliorative effect leading to higher P_n rates in sunflower crop under drought stress treatment. The findings reveal that improvement of root traits is worth attempting for the future crop behavioral responses under eCO₂ and drought stress environments. The study confirmed the beneficial effect of eCO₂ in maize and sunflower by ameliorating the adverse affects of drought stress.

A reproducible and highly efficient protocol for genetic transformation mediated by Agrobacterium has been established for greengram (Vigna radiata L. Wilczek). Double cotyledonary node (DCN) explants were inoculated with Agrobacterium tumefaciens strain LBA 4404 harboring a binary vector pCAMBIA 2301 containing neomycin phosphotransferase (npt II) gene as selectable marker, β-glucuronidase (GUS) as a reporter (uidA) gene and annexin 1 bj gene. Important parameters like optical density of Agrobacterium culture, culture quantity, infection medium, infection and co-cultivation time and acetosyringone concentration were standardized to optimize the transformation frequency. Kanamycin at a concentration of 100 mg/l was used to select transformed cells. Transient and stable GUS expressions were studied in transformed explants and regenerated putative plants, respectively. Transformed shoot were produced on regeneration medium containing 100 mg/l kanamycin and 250 mg/l cefotaxime and rooted on ½ MS medium. Transient and constitutive GUS expression was observed in DCN explants and different tissues of T0 and T1 plants. Rooted T0 and T1 shoots confirming Polymerase Chain Reaction (PCR) positive for npt II and annexin 1bj genes were taken to maturity to collect the seeds. Integration of annexin gene into the greengram genome was confirmed by Southern blotting.

The response of blackgram (Vigna mungo L. Hepper) to two levels of elevated carbon dioxide (550 and 700 ppm) in terms of growth and yield was investigated and compared with ambient CO 2 level (365 ppm) using open-top chambers. The growth parameters viz., length and weight of root and shoot, root:shoot ratio, leaf area and weight significantly increased at 700 ppm CO 2 when compared with 550 ppm. The percentage increase in total biomass at 700 and 550 ppm CO 2 was 65.4% and 39%, respectively compared to the ambient (chamber) control. The increase in total seed yield at 700 ppm (129%) was due to an increase in number of pods per plant and 100 seed weight, whereas at 550 ppm (88.7%) it was due to an increased number of pods/plant and seeds/pod. The results indicate variable responsive effects at different levels of CO 2 emphasizing the pertinence of research on elevated CO 2 in various agroecological inhabitations all over the world. The indication of higher responses for root and leaf at initial growth stages at the higher elevated level of CO 2 (700 ppm), which leads to better root establishment, achieving early photosynthetic efficiency and also better biomass production, and its improved partitioning can be reckoned as a positive aspect of increasing concentrations of CO 2 in atmosphere. The harvest index increased significantly to 35.7 and 38.4% at 550 and 700 ppm, respectively; it is a very important phenomenon in pulses for breaking the yield barrier.