ENHANCED TOLERANCE TO ABIOTIC STRESS IN TRANSGENIC TOBACCO BY OVEREXPRESSION OF A ZINC-FINGER PROTEIN GENE FROM RICE

The OSISAP1 gene was cloned via the differential screening of an indica rice cDNA library in an attempt to identify genes that show organ-specific and/or stress inducible expression3. OSISAP1 was expressed at a higher level in the root and the prepollination stage spikelet as compared to shoot. Further, expression analysis of OSISAP1 revealed that the gene is expressed in response to several abiotic stresses like cold, salt, drought, submergence, mechanical wounding, and heavy metals.

OSISAP1 codes for a zinc-finger protein, which shows homology in the AN1-type zinc-finger region to the human and mouse PRK-1-associated protein AWP1, Phaseolus vulgaris pathogenesis-related protein PVPR3, human and mouse zinc-finger protein ZNF216, Xenopus laevis ubiquitin-like fusion protein XLULFP, and the ascidian posterior end mark protein PEM6. OSISAP1 also shows homology in the A20-like zinc-finger region to AWP1, hZNF216, and mZNF216. A part of the encoded protein also shows homology to human transcription factor NF-kB p65 subunit.

The gene was overexpressed in tobacco under the control of a constitutive CaMV35S promoter to understand its function, and especially to determine whether the gene has a role to play in stress response. Transgenic lines were analyzed for cold, dehydration, and salt stress tolerance in the T1 generation. Germination, fresh weight gain, and bleaching were used as main parameters for comparing the response of nontransgenic and transgenic lines to different abiotic stresses.
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