Genetic Analysis And Fine-mapping Of A Leafy Head 3 Mutant In Rice (Oryza Sativa L.)

As the model plant for studying genome of monocotyledon plants,rice is the most important object for breeding research.The generative date decides varietal adaptability with area and season,and is a necessitous matter for solving to gain the precocious and fruitful variety.The date divides into three stages,including vegetative growth,reproductive growth and maturity stages.The two later ones are steady,so the heading date from seeding to heading can reflect generative trait of rice variety.A natural rice mutant lhd.3(leafy head 3) with delayed heading date and leafy head was isolated from progenies of a japonica cultivar,Changyou 94.In short-day conditions,outgrowth of new leaves (generally 3 leaves) and tillering on upper nodes continue in later stage of vegetative growth in the lhd3 mutant,which is similar to tree branching.Also it holds the delay in heading date(generally 10 days). But the number of basal tillers isn't changed.We got the conclusion as follows:1.The harvested mutant seeds were planted in Hainan in the winter.Their offsprings all showed the mutant trait that can be inherited stably.2.Classical genetic analysis with F₂ population of lhd3/Nanjing 6 indicated that the lhd3 phenotype was controlled by a single recessive gene.3.LHD3 gene was mapped with the F₂ population between two developed STS markers,wpla3 and wpla25,on the short arm of rice chromosome 1.Fine mapping delimited it to a 60 kb physical distance between a STS marker and a CAPS marker,WX6 and CAPS1,where 10 ORFs were predicted by Rice Genome Annotation(http://rice.plantbiology.msu.edu/index.shtml).4.At last we disposed the mutant and Changyou 94 with different geographical condition and different light length.The result showed that the trait of leafy head disappeared in Fuyang of China,but the heading date was still delayed.Short light can get mutant heading earlier indeed.Further cloning of LHD3 will contribute to the clarification of regulation mechanism for growth period and leaf-primordium development in rice.