Functional Analysis Of Lilium Small Heat Shock Protein(LimHSP16.45)in Arabidopsis Athsp17.6Ⅱ Mutants

Organisms can produce heat shock proteins (HSPs) under stress conditions. Howerer, the function of heat shock protein, especially small HSPs, in stress tolerance is not fully explored. To improve our understanding of sHSPs, a full-length cDNA encoding LimHSP16.45was islolated from Lilium(Lilium var. davidii unicoior Cotton) in the previous works of our lab. The results of the mutant analysis revealed that LimHSP16.45showed62%similarity of AtHSP17.6II. Genetic analysis of the Athsp17.611mutant indicated that the expression level of AtHSP17.611reduced, suggesting that it is a knockdown mutant. The Athsp17.611mutants had a defect in response to high temperature during seed germination and seedling establishment. To investigate function of LimHSP16.45, the CDS of LimHSP16.45was introduced into Athsp17.6Ⅱ mutants. Two independent T3lines were selected and the expression level of LimHSP16.45was determined by RT-PCR. Both transient and stable expression results showed that LimHSP16.45localize in cytoplasm. Functional analysis of LimHSP16.45was conducted:the POD (Peroxidase), CAT (catalase) and SOD (superoxide dismutase) activities were enhanced in transgenic plants compared to the wild type and mutant plants upon45℃treatment. Moreover, less hydrogen peroxide accumulation compared with Athsp17.6Ⅱ under45℃treatment; the content of soluble sugar and proline significantly increased in transgenic plants under45℃treatment. Under heat stress, LimHSP16.45transgenic lines showed less accumulation of MDA and lower electrolyte leakage than that of wild type plants and Athspl7.611mutant. Taken together, our results showed that LimHSP16.45functions as a positive factor might be involved in the response of plants to heat stress.