SlNAC1 Enhanced The Stress Resistance Of Transgenic Arabidopsis And The Mechanism Analysis

Plant-specific NAC transcription factors play a key role in plant growth and development,which resistance to water deficiency,salinity,high or low temperature,injury and other physiological processes.Preliminary work in our laboratory has cloned a NAC transcription factor from S.liaotungensis,which named as SlNAC1,and also has obtained the second generation seeds of transgenic pEGAD-Sl NAC1 Arabidopsis and transgenic pEGAD-GUS Arabidopsis.This study uses the third generation of homozygous diploid Arabidopsis analyzing the resistance to abiotic stresses and corresponding mechanisms.The main results are as follows:1.This study uses seeds of second generation transgenic Arabidopsis as material to screen the third generation of homozygous diploid Arabidopsis,using MS culture medium contained Basta.We obtain the transgenic pEGAD-SlNAC1 Arabidopsis named L1?L2?L3 and the transgenic pEGAD-GUS Arabidopsis named VT.The wild type Arabidopsis named WT.2.Parameters connected with physical development and physiological of transgenic Arabidopsis and wild type Arabidopsis were tested under abiotic stresses including drought,high salt and low temperature.The physical development indexes mainly including seed germination rate,root length,seeding survival rate,plant height and stomatal state.The physiological characteristics mainly including chlorophyll fluorescence,conductivity,proline content,SOD,POD and CAT.The germination rate of these Arabidopsis thaliana are all restrained differently,but WT and VT are more seriously under abiotic stresses.At the seeding growth stage,L1,L2 and L3 were more tolerant than WT and VT on root development,survival rate,plant height and stomatal state.Detection of chlorophyll fluorescence demonstrates that transgenic pEGAD-SlNAC1 Arabidopsis stand up against abiotic stress by means of photosynthesis.The contents of proline and activity of antioxidant enzyme in the transgenic pEGAD-SlNAC1 Arabidopsis are significantly higher than that in the WT and VT.It is effectively proved that the expression of exogenous gene,SlNAC1,in transgenic Arabidopsis reduced the damage of abiotic stresses and enhanced tolerance to them.3.We select the genes differentially expressed in transgenic SlNAC1 Arabidopsis compared to the wild type by cDNA microarry,which provides us with scientific basis for investigating the genes related to abiotic stresses.There were 3046 genes differentiallyexpressed more than twice in the total 43604 genes of transgenic SlNAC1 Arabidopsis.Gene Ontology(GO)analysis was performed on genes differentially expressed more than five-fold.It turned out that genes relevant to cellular components occupied 33.05%,genes correlated with molecular function accounted for 33.95% and genes pertinent to biological process constituted a 33.00% portion.The genes differentially expressed more than twice were processed through Kyoto Encyclopedia of Genes and Genomes pathways enrichment(KEGG)analysis.2431 genes were involved in 88 different signaling pathways.Among the differentially expressed genes,ABI4,NRT1.6,ADC1 and FBL17 involved in the regulation of seed germination in L2 increase the seed germination rate under stress conditions.The genes,such as PRXCA,EXPA7,EXPA8 and so on,are involved in the regulation of unidimensional cell growth and enhance the growth of root and shoots under stress conditions.The genes,AT2G14247,AT5G05270,AT5G40450 and so on are involved in the regulation of chloroplast formation and enhance photosynthetic capacity under stress conditions.SlNAC1 is one of the family members of NAC transcription factors,which improves the tolerance to abiotic stress of the transgenic Arabidopsis through regulating down-stream genes' expression.Studies have shown that the SlNAC1 gene has functions to abiotic stress indeed and revealed the regulation downstream genes,which provided a new materials for the study of the mechanism of stress resistance in plants.