Cloning And Function Preliminary Analysis Of Several Salt Stress Genes In Tomato

Soil salinization is one of the main abiotic stresses affecting growing and development of crops.Improvement of crop salt tolerance is one promising approach in fighting against salt stress.Based on the previous study on identification of the salt stress responsive genes,full length cDNA of 5 genes were isolated,vectors for gene functional analysis were constructed and introduced into tomato,primarily analysis of salt tolerance were carried out.The main results were as follows:1.Five early responsive genes under salt stress were cloned,among them,two genes belonged to NAC family(SlNAC1,SlNAM1),one gene belonged to Zinc-finger family (SlZF1) and the other two(SlSRG1,SlSRG2) were unknown genes.Sequencing results showed that SlNAC1 is 1327 bp in length,coding 301 amino acids(aa).aa alignment result showed SlNAC1 shared high identity with NAC genes from other plant species.The Genbank accession number(GI) of SlNAC1 is EU670750.SlNAM1(GI:EU670749) contained 1218 bp,coding 296 aa.aa alignment result also showed SlNAM1 shared high identity with homologous genes from other species.According to the aa alignment result, SlNAC1 and SlNAM1 belonged to the same type of transcription factor(NAC type). Phylogenetic tree was constructed for these two genes as well as their homologous genes using MEGA 3.1,and putative secondary and tierary protein structure were analyzed by SOPMA and SWISS-MODEL,the results supported that these two genes had the feature of NAC type transcription factor.SlZF1(GI:EU670748) encoded a zinc finger transcription factor,which was 1084 bp in length and coding 260 aa.SlSRG1 and SlSRG2 were two novel genes,SlSRG1(GI:EU670751) full-length cDNA was 1299 bp in length, coding 499 aa while SlSRG2(GI:EU670752) was 1810 bp in length and coding 499 aa.2.Over expressing and RNAi vectors of the above genes were construted and introduced into tomato via Agrobacterium.13,15 and 4 transformants were obtained for over-expression vector with SlNAC1,SlNAM1 and SlSRG2,respectively.PCR results showed that T-DNAs containing the corresponding genes were integrated into tomato genome.3.Semi quantitative RT-PCR results indicated that the transcriptional level of transgene was quite different in different individuals with the same expressing vector.4.Genetic segregation analysis was carried out and a number of offspring populations were obtained for downstream research work.5.Expression profile among different tissues(root,stem,leaf,flower,green fruit,and ripen fruit) of LA2711 were investigated using RT-PCR.