Correlation Analysis Of Zinc And Iron Contents In Japonica Rice Germplasm Resources And QTL Mapping Of Zinc Content In Grains Of Local Varieties In Ningxia

Rice,as the primary staple food for half of the world population,is also one of the major cereals of biofortified trace elements.Zinc and iron play a key role in the normal growth and metabolism of animals and plants,especially in countries where rice is the main grain,the deficiency of zinc and iron in human body is more common.Therefore,it is of great significance to improve zinc deficiency in human body by biological enhancement.The aim of this study was to provide a theoretical and molecular basis for the improvement of zinc content in rice grains by molecular breeding through association analysis and linkage analysis of QTL loci controlling Zn and Fe content in rice grains.In the present study,57 pairs of SSR markers were used to analyze the genetic diversity of 155 japonica rice germplasm resources in Ningxia.The correlation analysis between Zn,Fe content in grain and grain shape,the correlation analysis with SSR markers were carried out.An F2 population derived from a cross between a high zinc Ningxia local variety,Yanghebaipidao,and a low zinc variety,Ninggeng 35,was produced.The linkage genetic map was constructed by F2 generation segregation population.The QTL Interval Mapping method was used to map the loci of zinc content in grain.The main results are summarized as follows:1.Correlation analysis between zinc,iron content and grain shape of 155 japonica rice germplasm resources in Ningxia showed that zinc content was significantly positively correlated with iron content;zinc content was significantly positively correlated with grain length;iron content was significantly positively correlated with grain length;2.Through genetic diversity analysis of 155 japonica rice germplasm resources in Ningxia,the results showed that 155 japonica rice germplasm resources in Ningxia were divided into 4 subgroups.A total of 257 alleles were detected,among which there were 148.The average number of alleles per locus was 4.51 the average number of effective alleles was 2.60,and the number of alleles varied from one locus to another,with the range from 2 to 10.3.Through association analysis,it was found that there were three sites had significant correlation with the rice grain zinc content,there were RM5461-4,RM5647-2 and RM7356-1,whose contribution rate were 7.59%,5.89%and 4.72%,respectively.The allele RM5647-2 had the highest positive phenotypic effect,and the carrier variety was Changli No.5.There were 20 sites significantly associated with rice grain iron content,with 2.56%-7.33%explaining the phenotypic variance.The highest contribution rate was from the allelic variation RM3600-1.12-3 had the highest positive phenotypic effect and the carrier variety was Liang xiang No.5.4.QTL analysis of the F2 population showed that a total of eight QTLs for zinc content in grains were located on chromosomes 3,7,and 8.The phenotypic variance explained by these eight individual QTLs varied from 4%to 8%.Among them,qZn-7-3 was detected on chromosome 7,explaining 8%of the phenotypic variance,and the additive effect of the Yanghebaipidao-derived allele increased grain zinc content by 1.16mg/kg.