The Regulation And Mechanism Of OsSAPK10 On Plant Height

Plant height,one of the important agronomic traits of rice,is closely related to yield.The higher plant height makes plants more susceptible to lodging,and the shorter plant height leads to insufficient biomass accumulation,both of which can affect rice yield potential.Therefore,the proper plant height makes sense to guaranteeing rice yield,thus the study on plant height has important scientific significance and application prospect.Recently,many researches of phytohormone?abscisic acid,ABA?have focused on the response to stresses,however,there is a few researches of regulatory mechanism of ABA on rice plant height.In this study,wild type rice?Dongjin?,OsSAPK10?gene encoding the positive regulator of ABA signal transduction in rice?overexpression transgenic lines?OsSAPK10-OE?andOsSAPK10RNAinterferencetransgeniclines?OsSAPK10-RNAi?was used to investigated the OsSAPK10 regulates plant height by affecting rice heading and internode elongation.The main results of our study are as follows:1.The expression of OsSAPK10 was negatively correlated with rice height.Compared with the wild-type,the plant height of OsSAPK10-OE transgenic lines were significantly shorter,furthermore the higher expression level of OsSAPK10,the shorter plant height;Compared with the wild-type,the plant height of OsSAPK10-RNAi transgenic lines were significantly higher,and the lower expression level of OsSAPK10,the higher plant height.2.OsSAPK10 up-regulated the expression level of early heading genes and down-regulated the expression level of late heading genes,which led to early heading date,and reduced internode number and panicle length,ultimately resulting in reduced rice height.In OsSAPK10-OE transgenic lines,the expressions level of the early heading genes?such as OsFKF1,Ehd1,etc?were up-regulated,while the late heading genes?such as Ghd7,DTH7 etc?were down-regulated,the heading stage was significantly advanced,the internode number was decreased,and the panicle length was reduced by 21.01%and24.54%,compared with the wild type.However,in OsSAPK10-RNAi transgenic lines,the expressions level of the early heading genes?such as OsFKF1,Ehd1,etc?were down-regulated,while the late heading genes?such as Ghd7,DTH7 etc?were up-regulated,the heading stage was significantly delayed,and the panicle length was increased by 14.12%and 16.02%,compared with the wild type.3.OsSAPK10 inhibited the expressions level of GA biosynthetic genes,decreased the content of endogenous active GA,reduced the expressions level of genes that regulate GA signal transduction,reduced the expressions level of cell division and cell elongation related genes,inhibited internode growth and ultimately reduced the rice height.In OsSAPK10-OE transgenic lines,the expressions level of GA synthetic genes such as OsGA20ox3 etc were significantly down-regulated,GA inactivated genes such as OsGA2ox5 etc were significantly up-regulated,the content of active GA₄ was decreased,the expressions level of GA signal transduction regulatory genes such as d1?OsGID1?OsGRF1 were significantly down-regulated,the expressions level of cell division related genes such as OscycB:1etc and cell elongation related genes such as OsXTH8?OsXET?OsEXP1 were significantly down-regulated,and the uppermost internode length were decreased by 5.95%and 18.38%compared with the wild-type.However,in OsSAPK10-RNAi transgenic lines,the expressions level of GA biosynthetic genes such as OsGA20ox3 etc were significantly up-regulated,GA inactivated genes such as OsGA2ox5etc were significantly down-regulated,the content of active GA₄ was increased,the expressions level of GA signal transduction regulative genes such as d1?OsGRF1 were significantly up-regulated,the expressions of cell division related genes such as OscycB:1etc and cell elongation related genes such as OsXTH8?OsXET?OsEXP1 were significantly up-regulated.4.OsSAPK10 reduced the yield per plant.In OsSAPK10-OE transgenic lines,grains numbers as well as 1000-grain weight were significantly decreased compared with the wild-type.However,in OsSAPK10-RNAi transgenic lines,grains numbers were significantly increased,but 1000-grain weight were decreased compared with the wild-type.In conclusion,OsSAPK10 reduces the yield per plant by decreasing the grains numbers as well as 1000-grain weight,as a result of the reduced vegetative growth period.The reduced vegetative growth period can also reduce the internode number and panicle length.Furthermore,the reduced vegetative growth period is caused by premature transformation of plant vegetative growth to reproductive growth as a result of the advanced heading stage.And OsSAPK10 promotes the advancement of heading stage by promoting early heading genes expressions level and inhibiting late heading genes expressions level;During the internode elongation growth process,OsSAPK10down-regulates GA biosynthetic genes expressions level,decreases the content of active GA₄,down-regulates the expressions level of GA signal transduction regulative genes,which leads to reduced expressions level of cell division and elongation related genes in the internode,ultimately inhibits the growth of internode and reduces rice height.