Growth assessments of Nicotianatabaccumcv.Xanthitransformed with Arabidopsis thalianaP5CS under salt stress
Proline plays important role in osmo-adjusment and prevention of osmotic stress in plants. In order to analyze osmotic stress resistance, germination and growth pattern in vitro and in vivo, the Arabidopsis thalianaδ-1-pyrroline-5-carboxylate synthetase (P5CS) which is the regulatory enzyme of proline biosynthesis, was reverse transcribed, amplified into double stranded cDNA, cloned and transformed into tobacco using Agrobacterium tumefaciens mediated transformation. Seeds of chimeric T0
transgenic plants were grown; T1 and the succeeding T2 transgenic plants were obtained. Subsequently, wild type and binary vector transformed control plants along with T2 transgenic lines were exposed to salt concentrations from 0 to 250 mM during germination and growth stages. Results showed a significant difference (P < 0.0001) between T2 and control plants, while the control plants germinated in the presence of salt concentrations up to 50 mM and tolerated 100 mM salt during growth phase. Transgenic T2 lines were able to germinate in 200 mM NaCl and tolerated up to 250 mM salt during growth phase. Assessing proline contents, we observed 7.5 times more proline in T2 transgenic plants
than control plants in normal condition which increased up to 3.3 folds in stress condition. This osmotic stress resistance was further assessed for T3 generation against drought and salt stresses in vivo. Results indicated osmotic stress resistance of T3 generation as well as stable expression of P5CS along with achievement of homozygous transgenic lines.
Key words: δ-1-Pyrroline-5-carboxylate synthetase (P5CS), osmotic stress, transgenic plants, germination, growth phase.