QTL Mapping Of Brown Rice Protein Content In A RIL Population Of Rice And Analysis Of Genetic Diversity Of Aromatic Rice Varieties

Protein content is important traits in evaluation of nutrient quality of rice. Most of crop traits are quantitative in nature, which are controlled by polygene. It's very important for rice nutrient quality breeding improvement to map quantitative trait loci(QTLs) of brown rice protein content. Aromatic rice is regarded as pearl in rice because of its good quality, flavor, faint scent and tastiness. Therefore, it's very important to study the genetic diversities of the aroma rice which has provided the main materials for rice researchers. The objective of this study was to identify QTLs conditioning brown rice protein content using a recombinant inbred line(RIL) population. And analysis genetic diversity of aromatic rice varieties based on SSR. And fine mapping of the fragrance gene in rice linked the AP004463-13 of InDel marker on CHRO.8. The main results are as follows:1. QTL Mapping Construction of brown rice protein content in a recombinant inbred line(RIL) population of RiceThe objective of this study was to identify QTLs conditioning brown rice protein content using a recombinant inbred line(RIL) population derived from a cross between Zhongyouzao and Fengjin and its genetic linkage map by the composite interval mapping(CIM) of Windows QTL Cartographer 2.0. Six QTLs(qPc-3,qPc-6,qPc-7,qPc-8-1,qPc-8-2,qPc-11) showing significant additive effects for brown rice protein content were detected respectively. The six QTLs for brown rice protein content collectively explained 61.07% of the phenotypic variance, with the variance explained by a single QTL ranged from 3.79% to 19.41%. QTLs located in the vicinity of marker OSR34 on chromosome 8 displayed a major effect for protein content. Utilization of the QTL mapping on marker assisted selection for the improvement of grain quality in rice was also discussed.2. Genetic Diversity of Aromatic Rice Varieties Based on Markers of Functional gene and SSRGenetic diversity of 32 aromatic rice cultivars were analyzed by some markers of functional gene in rice and 60 SSR primers covered on 12 rice chromosomes. A total of 188 alleles were detected, among of which 126 alleles were effective. The average number of allels per SSR locus was 3.13 with a ranged from 2 to 6. The value of allelic polymorphism information content(PIC) ranged from 0.116 to 0.744, on an average, 0.467±0.023 per SSR maker. The average similarities coefficient was 0.697±0.0035 with a ranged from 0.51 to 0.96. UPGMA cluster analysis showed that the 32 cultivars could be classified into indica and japonica distinct classes at similarities coefficient 0.58, which was generally coincident with pedigree analysis. The results indicated that SSR markers could be employed in diversity identification for aromatic varieties and aromatic rice breeding. Consequently, marker of functional gene in rice could be used for measuring genetic diversity, assigning rice to geographical distribution, and analyzing its ecotype and pedigree relationship.3. Fine Mapping of the Fragrance Gene in RiceWith the development of modern biotechnology, the flavour or fragrance of aromatic rice is associated with the presence of 2-acetyl-1-pyrroline. A recessive gene(fgr) on chromosome 8 of rice has been linked to this important trait. In the proper studies, a F₂ segregation population derived from a cross between Jingxiangmi with jasmine fragrant and MR63 without fragrance were used to study the inheritance of fragrant and map the fragrance gene in rice chromosome 8. Genetic mapping of molecular markers and the fragrance phenotype demonstrated that the InDel markers AP005537-17 and AP004463-13 flanked fgr. The physical distance between AP005537-17 and AP004463-13 is about 252 kb. The data suggested that fgr was closer to AP004463-13(0.4cM) than to AP005537-17(1.6cM). Careful examination of mapping data suggested that one Bacterial Artificial Chromosomes(BAC)(clone AP004463) was most likely to contain the gene. Fragrance in domesticated rice has apparently originated from a common ancestor and may have evolved in a genetically isolated population, or may be the outcome of a separate domestication event. This is an example of effective human selection for a recessive trait during domestication.