Identification And Mapping Of Gene Involved In Rachis Internodes Of Lb 2308 Mutant In Rice

It is more important to panicle architecture that directly determine grain yield in rice(Oryza sativa L.).Although a number of key genes controlling panicle architecture,which have been cloned and characterized in recent years,their genetic and molecular mechanisms remain unclear.In this study,a panicle mutants lb2308 was identified by indica Yixiang 1B using ethyl methyl sulfonate mutagenesis(EMS).Genetic mapping and Mutmap analysis revealed that LOC_Os03g40540 existed in a single base substitution.We verified their biological function in rice.The main results are as follows:1.lb2308 mutant present a few phenotypes compare with wild type including longer basal internodes,clustered primary branch,low seed setting rate,reduced seeds in size,Sustained spikelets and semid warf phenotype featured with shorter culm internodes.2.Histological examination showed that the longer basal internodes of the lb2308 plants were due to becoming long for cell length and becoming more for cell numbers.Besides,the shorter culm internodes were related to becoming short for cell.3.Genetic analysis indicated that the phenotype of lb2308 mutant was regulated by a single recessive nuclear gene.LB2308(LOC_Os03g40540)was identified using map-based cloning combined with Mutmap analysis,and found a new allele of BR-Deficient dwarf1 brd1,which belonging to the cytochrome P450 superfamily.The function of LB2308(LOC_Os03g40540)involve in the BR biosynthesis pathway.Besides,results suggested that a amino acid substitution residing(Asp168Val)in the encode region of LB2308 by further research.4.The results showed that LOC_Os03g40540 take part in the panicle architecture,plant height and seed size changes by exogenous BR treatment,co-separation experiment,expression analysis of BR gene and determination of BR content.5.Gibberellin content in lb2308 than in wild type continued to accumulate during the development of the basal internodes.We deduce that significant elongation of the basal internodes is due to accumulation of GA.6.At present,mutants involved in BR in rice had considerable reports,and main character including shorter grain length and narrower grain width.However,the grain width of lb2308 is slightly wider than that of wild type.We deduce that width grain derived from significantly high expression of gene qGW8 in lb2308 than in wild type.In brief,these results showed that the specific mutation in LB2308 influenced development of panicle architecture,plant height and seed size.