Engineering drought tolerant tomato plants over-expressing BcZAT12 gene encoding a C2H2 zinc finger transcription factor

Efficient genetic transformation of cotyledonary explants of tomato (Solanum lycopersicum, cv. H-86, Kashi vishesh) was obtained. Disarmed Agrobacterium tumifaciens strain GV 3101 was used in conjugation with binary vector pBinAR containing a construct consisting of the coding sequence of the BcZAT12 gene under the regulatory control of the stress inducible Bclea1a promoter. ZAT12 encodes a C2H2 zinc finger protein which confers multiple abiotic stress tolerance to plants. Integration of ZAT12 gene into nuclear genome of individual kanamycin resistant transformed To tomato lines was confirmed by Southern blot hybridization with segregation analysis of T1 plants showing Mendelian inheritance of the transgene. Expression of ZAT12 in drought-stressed transformed tomato lines was verified in T2 generation plants using RT-PCR. Of the six transformed tomato lines (ZT1–ZT6) the transformants ZT1 and ZT5 showed maximum expression of BcZAT12 gene transcripts when exposed to 7 days drought stress. Analysis of relative water content (RWC), electrolyte leakage (EL), chlorophyll colour index (CCI), H2O2 level and catalase activity suggested that tomato BcZAT12 transformants ZT1 and ZT5 have significantly increased levels of drought tolerance. These results suggest that BcZAT12 transformed tomato cv. H-86 has real potential for molecular breeding programs aimed at augmenting yield of tomato in regions affected with drought stress.