| According to statistics,rice,as a kind of staple food,feed more than half of the world’s population.Fully excavating the yield potential of rice varieties fully through the genetic improvement,could protect the safety of grain production.Breeding work is used to create or modify germplasm resources,so people can increase the rice grain yield.Tillering is an important agronomic trait and the number of tillers has a direct impact on the plant type and grain yield.So,breeding ideal rice tillers and high yield through studying rice tillering is a common goal to all breeders.In recent years,the rapid development of biological science made the complex mechanism of regulating rice tilling clearer.Specially,a lot of rice genes involved in regulating tillering were cloned through molecular biology.Strigolactones(SLs)are a class of phytohormone which play essential roles in regulating rice tillering,the pattern of strigolactones suppressing shoot branching as well as functional genes are highly conserved in monocots and dicots.ATMAX1 in Arabidopsis is an important gene involved in the biosynthesis of SLs through encoding P450.Our study found 5 MAX1 homologous genes through sequence blast,namely OsMAX1a,OsMAX1b,OsMAX1c,OsMAX1d and OsMAX1e.Among them,OsMAX1a and OsMAX1e have stable and high expression in rice tissues.Our experiments verified that the overexpression of OsMAX1a and OsMAX1e gene in Arabidopsis can rescue the maxi branched mutant phenotype,and the interference of OsMAX1a and OsMAX1e gene expression in rice respectively can increase rice tillering number.At the same time,gene OsMAX1a and OsMAX1e expression in offspring of interference rice decreased prominently.It suggested that OsMAX1a and OsMAX1e had similar function with MAX1 controlling plant tillering.Furthermore,applying GR24 can inhibit the expression of OsMAX1a and OsMAX1a gene and P-starvation can improve the expression of OsMAX1a and OsMAX1e gene to promote the biosynthesis of SLs.In addition,IAA、Kinetin(a cytokinin:KT)and NPA(N-1-napbthyphthalamic acid)treatment apparently had remarkable effect on the expression of OsMAX1a and OsMAX1e.Taken together,the results demonstrated that the expression of OsMAX1a and OsMAX1e gene can respond to the SLs level and they were involved in the biosynthesis of SLs regulating rice tillering. |
