The Transcriptome Studies Of Receptor-Like Kinase Osrpk1in Auxin Signal Transduction And Polar Transport

With range of plant receptor-like kinase involed in plant growth and development,hormone signal transduction,disease resistance and other channels,so the research of receptor-like kinase is significant.This article aims to signal transduction of receptor-like kinase in plant through studying transcriptome of a new receptor-like kinase OsRPK1.In previous work, our lab analysised plasma membrane proteome from rice, identified a series of protein responsing to salt stress, one of which, molecular weight is98kDa, theoretical pI is5.93, and the expression level is up regulated remarkably after treatment with salt. Retrieved agaist the rice protein database, this protein is a putative receptor-like kinase which we tentatively named as OsRPK1.The coding region of OsRPK1is2910bp, encoding969amino acids.In order to study the fuction of OsRPK1in signal transduction, first we used RT-PCR for tissue-specific expression of OsRPK1and the OsRPK1highest expression level in root tips and leaves of rice, OsRPK1expression of stems was significantly lower than the roots and leaves, due to polar auxin transport in root tips and leves and other parts where have a stronger differentiation have more auxin,in these parts OsRPK1highest expression,we initially speculated that OsRPK1may be related to auxin signal transduction or polar transport. Then rice were hydroponiced with plant hormones Ethephon (1mM),2,4-D (100μM),6-BA (100μM), GA3(100μM), ABA (100μM), BR (10μM), MeJA (100μM), SA (1mM) hydroponic3h,12h,48h, take the rice root tip as the experimental material, and then we re-use of semi-quantitative RT-PCR methods to detect OsRPK1expression in root tips after different hormones treatment and found that OsRPKl expression continue to rise in48h within2,4-D,within Ethephon,6-BA, ABA, MEJA treatment OsRPKl expression rise in3h while the expression will gradually dccline in12h,and within SA treatment the expression continue to rise in12h,after the expression will decline. The results show that OsRPK1may be mainly affected by auxin regulation, OsRPK1as a receptor-like protein kinase, may be involved in auxin signal recognition or transport.To further study the function of OsRPK1in polar auxin transport and in auxin signal transduction,we built two plant expression vectors:pGSA1285-OsRPK1(+) and pGSA1285-OsRPK1(-),and the two plasmids were connected into Agrobacterium tumefaciens EHA105by using freeze-thaw method, Agrobacterium infect embryogenic callus,after the resistance screening, the resistent callus differentiate seedlings. Followed we compared OsRPK1expression in wild-type rice with pGSA1285-OsRPK1(+) into seedlings and pGSA1285-OsRPK1(-) into seedlings by semi-quantitative RT-PCR method, the results show that we successfully get OsRPK1overexpressing plant and OsRPK1underexpressing plant. We used real-time quantitative PCR mothod to detect the expression of the early auxin response genes such as IAA1,IAA3,IAA5,IAA6,IAA9and IAA19in transgenic rice and wild type rice,the results showed that six kind genes were all induced to express by auxin,but also found the inductions were inhabited in underexpressing rice compared with wild type rice,but in overexpressing rices the expression of IAA1,IAA6,IAA9and IAA19induced by auxin were lower than wild types,in two stains the expression of IAA3and IAA5were slightly higher than wild types while there was each stain lower than wild types.This indicated that OsRPK1participates in intracellular auxin signal transduction or polar auxin transport. Second, we compared the expression of auxin signal translation genes in wild-type rice and transgenic rice,we found OsRPKl affected multiple auxin signal-related genes expression. After that we analyzed the auxin signal transduction-related genes and polar auxin transport relatedgenes in wild-type rice,overexpressing rice and underexpressing rice,and we found that there was no significant trend between wild type rice and transgenic rice,but the expression of PIN family,AUX1and LAX family downregulated in overexpressing rice while increased in underexpressing rice.ALL these results suggested OsRPK1was involed in polar auxin transport.We first proved OsRPK1gene was involved in polar auxin transport, but how OsRPK1involed in polar auxin transport remains unclear, it will be our main goal on future research.