| Stem cells play an important role in the growth and development of plants.The aboveground tissues and organs are derived from the division and differentiation of stem cells in the shoot apical meristem(SAM);The growth of underground roots comes from the division and differentiation of stem cells in the root apical meristem(RAM);and the lateral growth of plants,such as the thickening of roots and stems depends on the differentiation of cambium stem cells.WUS、WOX5 and WOX4 play a central role in stem cell maintainance of the SAM、RAM and cambium respectively.Plant have to adjust its growth and development to adapt to changing environment.Salt stress significantly inhibits plant growth and development.However,it still remains to be elucidated how salt stress regulates plant stem cell function.Methionine synthase 2(AtMS2)catalyzes the last step of de novo synthesis of methionine in cells.In this research,we found that AtMS2 protein in the nucleus increases significantly in response to the stimulation of NaCl;AtMS2 protein can bind to WUS、WOX5 and WOX4 proteins to form complexes which further inhibit the activities of WUS、WOX5 and WOX4 promoters by binding to their promoters respectively.AtMS2 has been shown to repress the expression of WUS、WOX5 and WOX4 genes under salt stress.The expression levels of WUS、WOX5 and WOX4 proteins in WT were decreased significantly under NaCl stress,while these proteins in atms2 were expressed at a relative higher level.The germination,leaf differentiation,and root elongation of WT were significantly inhibited by NaCl stress,while atms2 mutant showed a higher resistance to salt stress.Therefore,the loss-of-funciton ofAtMS2 causes an insensitivity to salt stress.Taken together,AtMS2 protein mediates the salt signalling and inhibits plant growth and development under salt stress. |
