The Expression Profile Investigation And Functional Characterization Of Rice OsMPK7 Protein

Rice is an important food crop and model plants for basic research.The growth and development of rice is influenced by environment cues.The change of the environment and the infection of pests and pathogen can affect the yield of rice.MAPK(Mitogen-activated protein kinase)is highly conserved among higher organisms and play important roles in maintaining the growth and development of plants,and response to biotic and abiotic stresses.There are 1 5 MAPK genes in rice.This study aims to characterize the function of rice OsMPK7 gene.In this study,the full length cDNA sequence of OsMPK7 gene was cloned by PCR,the recombinant protein was expressed in E.coli.and the monoclonal antibody was generated.Tissues from different parts of rice at different growth and development stages were collected,Western blot(WB)was used to detect OsMPK7 protein expression in rice tissues.In the flowering stage of rice.the expression of OsMPK7 protein in glumes,young panicles.leaves,occipital and leaf sheaths was higher than that in root.The expression of OsMPK7 protein in the lower stem and node is not as high as in the upper stem and node.In the young panicle,the expression abundance of OsMPK7 protein in small panicle was slightly higher than that in larger panicle.In mature stage,the higher the degree of leaf aging.the lower the expression of OsMPK7 protein.In summary,OsMPK7 protein is expressed in multiple tissues constitutetively,but mainly in the shoot of rice,while barely detectable in root,thus the OsMPK7 protein was also expressed with tissue-specific way.The rice leaves under cold.hot.drought,constant light and constant dark were collected.The WB results showed that the expression of OsMPK7 protein was significantly down-regulated under drought stress.while no significant change was detected under the rest stress conditions.In order to further study the function of OsMPK7 gene,an overexpression vector and an RNAi vector were constructed and introduced into rice TP309 by agrobacterium-mediated method.Homozygous transgenic plants were identified based the screening of progeny.Field experiments showed that the overexpression of OsMPK7 gene had negative effects on rice growth,including lower seed setting rate.shorter plant height and fewer tiller numbers.Treatment of wild-type seeds and homozygous transgenic seeds with 20%PEG-6000 showed that drought stress inhibited the germination of overexpressed transgenic rice.In the seedling stage.it was found that the OsMPK7 overexpressed plants were sensitive to drought stress.while the growth of RNAi plants under drought stress was not significantly changed compared with wild type.indicated that overexpression of OsMPK7 gene reduced tolerance to drought stress.Under jasmonic acid(JA)treatment.the expression of OsMPK7 protein was up-regulated.Additionally,it was found that RNAi transgenic plants showed impaired resistance when inoculated with Xoo(Xanthomonas oryzae pv.oryzae).This study enhanced the understanding of the function of OsMPK7 gene.