| GRPs(Glycine-rich Protein)are a type of glycine-rich protein.This family has diverse functions in plant growth and development and stress responses.However,the biological function of BrGRP genes in response to abiotic stress is still poorly understood.In this study,systematic bioinformatics analysis was performed on BrGRP genes family in Chinese cabbage,the funciton,including temporal-spatial expression,stress response,and heterologous expression in Arabidopsis thaliana,of three BrGRP genes: w546(Bra030284),w1409(Bra014000)and BrGRP1(Bra004066)were further identified.The research results are as follows:(1)Through homology comparison analysis,a total of 64 BrGRP genes were identified in Chinese cabbage.Further predictions of physicochemical characteristics indicate that 62.5% of BrGRP is basic,53.1%of BrGRP is stable,and 79.7% is hydrophilic.These identified BrGRP genes were also located in 10 chromosomes and three different subgenomics of Chinese cabbage,and 43 orthologous GRP genes were found between Chinese cabbage and Arabidopsis.According to the analysis of open transcriptome data,64,52,and 39 BrGRP genes were abnormally expressed under high temperature,low temperature,and drought stress,respectively.In addition,many stress-related cis-acting elements were found in their promoter regions,such as DRE,MYC,MYB,and ABRE,which corresponded to their differential expression.In a word,the BrGRP genes show abnormal expression under stress,and some of them participate in multiple stress responses,which indicating their potential role in multiple abiotic stresses.(2)q RT-PCR showed that two RB-GRP(Glycine-rich RNA-binding Protein)genes,w546 and w1409,were detected to be expressed in leaves,roots,and flowers,especially highly expressed in leaves and roots of Chinese cabbage.Two genes could also be upregulated by vernalization or salt stress,particularly in roots by salt stress,which indicating that two RB-GRP genes could be irritated by adversity stress such as salt.(3)Overexpression of two RB-GRP genes(w546 and w1409)in Arabidopsis were obtained by flowerdip methods.Compared to wild-type Arabidopsis Col-0,overexpressing w546 in transgenic Arabidopsis(w546OX)showed more sensitivity in seed germination under NaCl(100-150 mmol·L-1),mannitol(300mmol·L-1)or ABA(0.1-0.3 μmol·L-1)stresses.At the same time,the survival rate of w546 OX seedlings and the length of main root(PR)under NaCl or ABA treatment were also improved.However,the seed germination rate of transgenic Arabidopsis overexpressing w1409(w1409OX)showed more tolerance to NaCl,mannitol or ABA stress,and the survival rate and main root length of w1409 OX seedlings were also improved,which were all exactly opposite to the w546 OX transgenetic lines.In addition,the expression of ABA response genes(ABI5,ABF3,NCED3)and salt stress response genes(DREB2A,At MYB2,RD29 B,SOS2)under NaCl(150 mmol·L-1)stress were all upregulated in w546 OX and w1409 OX plants than that in control.These results suggested that two RB-GRP genes may activate ABA signal transduction pathway,although with the different respond to salt stress.(4)overexpressing BrGRP1(non-RB-GRP)in transgenetic Arabidopsis BrGRP1 OX showed more senestive in seed germination under NaCl and mannitol stress.The survival rate of BrGRP1 OX seedlings and the main root(PR)length were also more sensitive to NaCl or ABA stress.However,the sensitivity of seed germination was reduced under ABA stress(0.1-0.3 μmol·L-1).q RT-PCR showed that the expression levels of ABA response or salt stress response related genes in BrGRP1 OX plants were all downregulated under NaCl(150 mmol·L-1)stress than control.All these results suggested that BrGRP1 gene may participates in the response of salt stress and negatively regulated ABA signaling pathway.In summary,three BrGRP genes showed different effects on plant stress resistance were identified by systematic identification,quantification of spatiotemporal expression,and stress treatment,of which the molecular mechanisms were worth further studying. |
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