Ramanna, Hema , Muthappa, Senthil-Kumar , Reddy, Chandrasekhara , Makarala, Udayakumar .
Acclimated stress responses of the transgenic tobacco plants expressing mtlD gene in constitutive and stress inducible fashion under various abiotic stresses.
Water deficit, salinity and oxidative stress are major abiotic factors that limit crop productivity in semiarid areas. Cellular accumulation of mannitol alleviates these abiotic stress effects. In this study we developed transgenic tobacco plants expressing mtlD (for the biosynthesis of mannitol). Initially the transformants were confirmed for the presence of the transgene by PCR and their expression pattern was studied by RT-PCR. We compared the performance of transgenic plants expressing mtlD driven by either constitutive (CaMV35S) or inducible (osmotin) promoter under different stress conditions. Under water deficit and salinity stress, the expression levels of mtlD transcripts were not altered in CaMV35S-mtlD lines and found to have equal levels of expression as that of non-stress. However, the lines with stress inducible expression showed higher levels of mtlD transcripts. Inoculating the transgenic leaf segments in MS medium supplemented with PEG or NaCl produced more number of shoot-lets compared to the wild type. The excised leaf segments from the osmotin-mtlD lines exposed to high light stress in the presence of methylviologen maintained more cell viability and less reduction in chlorophyll content than CaMV35S-mtlD lines. In all the experiments the stress was imposed gradually to allow the initial acclimation and later exposed to the severe stress levels. Interestingly the transgenic lines expressing mtlD gene in stress inducible manner exposed to acclimated stress showed better performance. Transgenics expressing mtlD under constitutive and inducible promoter showed only less tolerance under non-acclimated conditions. We have concluded that the performance of transgenic lines expressing stress genes should be studied only with prior acclimation stress.
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1 - University of Agricultural Sciences, crop Physiology, Deapartment of Crop Physiology, University of Agricultural Sciences, GKVK, Bangalore, Karnataka, 560065, India
2 - Samuel Roberts Noble Foundation, Plant Biology
3 - University of Agricultural Sciences, Crop Physiology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM