Establishment of a system for regeneration and transformation of Tamarix chinensis Lour. and functional analysis on transient transformation of TcSYP121 gene

【Objective】To establish a regeneration system and genetic transformation system of Tamarix chinensis Lour. and analyze the function of transiently transformed T. chinensis syntaxin（TcSYP121） gene， in order to provide theoretical re-ferences for the screening of candidate genes of T. chinensis molecular resistance breeding and the improvement and ecological restoration of saline and alkaline soil. 【Method】T. chinensis regeneration system was established by univariate analysis of the selection of explants， disinfection treatment， medium type and hormone combination concentration at each stage （primary， differentiation， proliferation and rooting）； four factors affecting the transformation system （preculture time， infestation time， co-culture time and Agrobacterium concentration） were analyzed by orthogonal test； and the transformation system of T. chinensis was established by the results of PCR amplification electrophoresis. Meanwhile， the transient transformation of TcSYP121 gene obtained overexpression plants （OE） and virus-induced gene silencing plants （VI）， and phenotypic observation， plant superoxide anion dyeing solution（NBT） and diaminobenzidine method （DAB） staining， salt gland diameter and density， chlorophyll content， superoxide dismutase （SOD） activity， peroxidase （POD） activity， and the relative expression of the TcSYP121 gene were determined to analyze the function of TcSYP121 gene. 【Result】The optimal explants were the tender stem segment of T. chinensis， the most suitable disinfection method was 5% sodium hypochlorite（NaClO） ，the best disinfection time was 5min， the most suitable primary medium was MS medium， and the best differentiation medium was MS+1.0 mg/L 6-BA+0.1 mg/L NAA. The best rooting medium was 1/2 MS+0.5 mg/L IBA. The results of orthogonal test in the transformation system were the best pre-culture time being 2 d， the optimal infection time being 5 min， the optimal co-culture time being 2 d， the optimal Agrobacterium concentration OD₆₀₀ value being 0.8， the antibiotic concentration Cef being 300 mg/L， and kanamycin（Kan） screening pressure was 30 mg/L. PCR amplification electrophoresis results showed that positive transgenic plants could be obtained using this genetic transformation system. The results of salt tolerance function analysis of transiently transformed TcSYP121 gene of T. chinensis showed that under salt stress， the chlorophyll content in VI and control （CK） decreased significantly （P<0.05）， and the OE decrease was not significant （P>0.05）； OE T. chinensis had a higher level of SOD and POD activities than VI and CK， the relative expression of TcSYP121 gene in OE was higher than that in CK and VI. 【Conclusion】The regeneration system and genetic transformation system of T. chinensis were preliminarily established， and overexpressed and silenced T. chinensis were obtained through transient transformation of T. chinensis Lour.， which confirmed that the TcSYP121 gene could improve the salt tolerance of T. chinensis.