OVEREXPRESSION OF KVP5CS1 INCREASES SALT TOLERANCE IN TRANSGENIC TOBACCO

Proline is a generally accumulated osmolytes in plants under salt stress. Overexpressing P5CS gene for more proline production is considered as an effective strategy to improve plant salt tolerance. In this study, KvP5CS1 was cloned from a halophyte Kosteletzkya virginica and transferred to the genome of tobacco (NC89) by Agrobacterium-mediated method. Under normal condition, there is no obvious difference in the growth, chlorophyll and proline content, malondialdehyde (MDA) content, superoxide dismutase (SOD) and peroxidase (POD) activity between wild-type (WT) and transgenic seedlings, except that catalase (CAT) activity in wild type was lower than that in transgenic seedlings. However, after treatment by 200 mM NaCl stress for 14 days, transgenic seedlings grew better and showed higher levels of chlorophyll and proline, stronger antioxidant enzyme activities, lower level of malondialdehyde (MDA) than wild type seedlings. These results suggested that overexpression of KvP5CS1 resulted in proline accumulation, stronger antioxidant capacity and increased salt tolerance in transgenic tobacco, indicating KvP5CS1 was involved in plant salt tolerance and might be a promising gene to breed salt-tolerant crops growing in salinized farmlands and coastal lands.