Evaluation And Gene Mapping Of A Grain Shattering Mutant In Rice (Oryza Sativa L.)

Rice is one of the most important grain crops in China,it's shattering rate directly affects the quality and yield of the rice harvest.Therefore,to comprehensively understand the regulation mechanism of reducing the loss of rice yield due to shattering particle brings has the important practical significance.09-4240 is a late maturing japonica rice,with moderate grain shattering.4240sh,an easy shattering mutant,was obtained from 09-4240 after EMS treat.Easy shattering characteristics of 4240sh showed stable heredity in many generations.An investigation into the grain shattering of 4240sh began at 2 weeks after heading,and found that 4240sh had a few of grains dropping off at 3 weeks after heading in natural condition.At the 28d,35d,42d and 49d after heading,the grain shattering percent increased to 25.5%,56.5%,78%,88.2%respectively in field.the easy shattering characteristics of 4240sh was similar with wild rice.4240sh was crossed with two indica accession B96-TK and GS1649A,that showed difficult shattering.F1 presented easy shattering characteristics as 4240sh,suggesting that the easy shattering trait is dominant.The shattering degree in F2 population was classified from 0 to 5(shattering from difficult to easy)with reference to the parents.the 0-2 level qualitatively belong to difficult shattering,3?5 level belong to easy shattering.The ratio of easy to difficult in F2 was consistent with the single gene segregation.Choosing difficult shattering recessive individuals from F2 of B96-TK/4240sh built a DNA mixed sample,to screen linkage markers.SSR marker RM131 on chromosome 4 showed the same PCR amplified bands between the mixed sample and B96-TK.This result indicated the genetical linkage between shattering gene and marker RM131.Further,RM131 and the polymorphism markers nearby RM131 on chromosome 4 was used to screen marker type in F2 population.QTL analysis by ICIMapping showed that q-SH4,a major QTL for grain shattering,was mapped dt the interval of RM6441 and RM8820 on chromosome 4,explaining 80.46%phenotypic variation for grain shattering with a LOD score of 31.01.The easy shattering allele was derived from 4240sh.By analyzing the phenotype of 6 recombinants from 236 plants of two F2 populations,q-SH4 was finally narrowed to RM6441 and RM1113,with a physical distance of 377kb.The positioning interval of q-SH4 was coincided with the site of a known shattering gene SHA1,inferring that q-SH4 is an allele of SHA1.