| RAV(Related to ABI3/VP1)transcription factors are involved in diverse functions in higher plants,containing both AP2 domain and B3 domain.Despite the existing research of RAV gene family in cotton,soybean and Arabidopsis thaliana,there is no research about RAV gene family in saline model plant.A total of eight Ts RAV genes were isolated from the genome of Thellungiella salsuginea and could be divided into two groups(A-and B-group)based on bioinformatics analysis and A-group contains Ts RAV1-Ts RAV4,B-group contains Ts RAV5-Ts RAV8.We found that the transcription of all eight Thellungiella salsuginea RAVs followed a gradual decline during seed germination(from 0 d to 4 d).In Thellungiella salsuginea seedling,transcripts of group A(A-Ts RAVs)were gradually and moderately reduced by salt treatment but rapidly and severely repressed by ABA treatment.In comparison,with a barely detectable constitutive expression,the transcriptional level of group B(B-Ts RAVs)exhibited a moderate induction in cotyledons when treated with ABA.We found that only 35S:A-Ts RAVs showed weak growth retardation including reduced root elongation by analying Ts RAVs transgenic Arabidopsis under Na Cl,ABA and drought stress,suggesting their roles in negatively controlling plant growth.With the presence of Na Cl,seed germination and seedling root elongation of all plants including wild type and 35S:Ts RAVs plants were retarded and a moresevere inhibition occurred to the 35S:A-Ts RAV transgenic plants.ABA treatment only negatively affected the germination rates of 35S:A-Ts RAV transgenic seeds but not those of 35S:B-Ts RAV transgenic seeds.All 35S:Ts RAVs transgenic plants showed a similar degree of reduction in root growth compared with untreated seedlings in the presence of ABA.Furthermore,the cotyledon greening/expansion was more severely inhibited 35S:A-Ts RAVs than in 35S:B-Ts RAVs seedlings.Upon water deficiency,with a wider opening of stomata,35S:A-Ts RAVs plants experienced a faster transpirational water loss than wild type and 35S:B-Ts RAVs lines.Taken together,our results suggest that two groups of Ts RAVs perform distinct regulating roles during plant growth and abiotic defense including drought and salt,and A-Ts RAVs are more likely than B-Ts RAVs to act as negative regulators in the above-mentioned biological processes.This article makes identification and analysis of RAV gene family in the saline model plant,Thellungiella salsuginea.It is an important supplement for the research of RAV gene family function. |
