Mapping And Identifying Of QTLs For Seed Storability In Rice (Oryza Sativa L.)

Rice（Oryza sativa L.）is the most important food crop in China.The storability of rice is great significance to ensure the security of national food and rice production.The storability of rice is a complex quantitative trait affected by many factors,such as heredity,growth and development status,harvest time and water content during storage.Screening storage tolerant germplasm resources and mapping QTL are helpful to elucidate the genetic basis of seed storability,and promote the innovation of storage tolerant germplasm and molecular marker assisted selection breeding.Due to the different materials and aging methods used in the previous research on rice storage tolerance genetics,the results of rice storage tolerance QTLs are different;In addition to the lack of genetic research on storage tolerance such as indica japonica cross rice,it is very necessary to expand the types of rice materials and study the storage tolerance characteristics and mechanism of different types of rice varieties such as conventional japonica rice,hybrid japonica rice and indica japonica cross rice,so as to provide theoretical basis and technical support for optimal storage of rice.The storability of 37 rice germplasm resources with different genotypes were evaluated by artificial aging,and the correlation between indica content index（Fi）and seed storability was analyzed.Furthermore,a Double Haploid（DH）population containing 154 lines was constructed using anthers of F₁generation derived the cross of between restorer line fan 38 and japonica restorer line fan 26,and QTL mapping analysis was conducted for rice seed storability.The main results are as follows:1.The germination rate of all tested materials decreased upon artificial aging treatment,and the storability of indica-japonica hybrid rice was weaker than japonica hybrid rice and inbred japonica rice.The higher basal metabolism level may result in the weak resistance to storage of indica-japonica hybrid rice.2.Three varieties,fan 12,fan 32 and fan 38,with high resistance to storage were screened from 15 restorer lines.After 15 days aging,the germination rate of fan 12,fan32 and fan 38 were more than 50.00%,and the storage index,respectively,were 70.37%,63.10%and 73.86%,which was significantly higher than other varieties.Indica contents of 15 restorer lines were determined by 34 pairs of Indel markers.It was found that the storability index（SI）of rice was significantly positively correlated with Fi（correlation coefficient was 0.72）.These results indicated that there were more favorable alleles for rice storage in indica rice genome.3.The DH population and its parents were used for 2b-RAD simplified genome sequencing,and 867,521,818 high-quality genome tag sequences were obtained.7175SNP loci were obtained through sequence comparison,SNP typing and filtering.These markers were classified as 666 bins by QTL Icimapping software to construct a genetic linkage map.4.After 10 days of aging of the DH population,the distribution of SI is mostly between 60.00%-70.00%,with a skewness value of 0.20,which is approximately a continuous normal distribution.Whereas after 15 days of aging,the distribution SI of DH lines is mostly ranged from 0.00%to 10.00%with a skewness value of 1.45,and shown a continuous distribution.The SI of DH population aged 10 days and 15 days was significantly correlated（correlation coefficient 0.432）.These results suggested that the storability trait of rice is a quantitative trait.5.Six QTL related to storability were detectedon chromosomes 3,5,6,11 and 12,respectively.The LOD values ranged from 3.45 to 6.80,which could explain 6.16%-13.00%of phenotypic variation,and the additive effect ranged from 6.76%to 6.12%.QSI-12 locus can be detected at both 10 and 15 days of aging.QSI-5a and q SI-6 were detected only at 10 days of aging,while q SI-3,q SI-5b and q SI-11 were detected only at15 days of aging storability,and q SI-3,q SI-5b and q SI-11 were the first reported site related to storage tolerance in rice.In addition,there were 32 pairs of epistatic interaction sites,most of which existed between non-additive effect sites,suggesting that epistatic interaction was an important part of regulating rice storability.