| The area grown to indica hybrid rice occupies57percent of total rice area in China, just only5percent in japonica hybrid rice. It is a significant reason that the low out-crossing rate of male sterile line and the high cost of seed production. In2011, the State Department issued that the effective, safe seed production technology and the advanced, applicable machine need to be extended and used. But now, in the process of hybrid rice seed production, spraying GA3, clipping leaves and artificial supplementary pollination are the popular practice for releasing the rice ear encolsed in the leaf sheath and improving the posture of fertilization to remove the barrier of cross pollination and increase seed production yield. This operation requires not only high-intensity labor, but also high level operating techniques. In addition, leaf cutting violate plant growth and development laws, because80percent of rice seed yield is supplied by the photosynthesis which flag leaf and the second leaf product. No Clipping leaf, playing photosynthesis of flag leaf and the second leaf, the full supply of organic nutrient is one of effective seed production technology. It has important significance in solving the problem of leaf cutting and the low yields in seed production that modifying seed production related traits of male sterile line or binary CMS line, which used to remove the barrier of cross pollination. Two studies were conducted in this thesis. First, analysis of main-effect QTL and digenic epistatic QTL for thirteen seed production related traits were conducted using3populations derived from Xiushui79/Cbao combination in japonica rice, and genetic basis analysis of these QTLs were conducted. The3populations are254recombinant inbred lines (RILs) and two backcross hybrid populations derived from these RILs respectivly. Second, eight8863B/A7444//863B BC2F1families in japonica rice were continued to be selected based on SSR markers to develop A7444CSSL population in863B background. According to QTL mapping results of flag leaf using863B/A7444BC1F1population, big flag leaf angle NIL population was developed based on SSR markers genotype and phenotype at the same time.The results obtained were as follows:1. In total,71main effect QTL controlling thirteen seed production related traits were detected in three populations, distributed on11chromosomes except for chromosome6. Among them, qFLA9.1simultaneously detected in RIL, XSBCF1and CBBCF1population was a stable main effect QTL controlling flag leaf area, and its contribution rate was16%,60%and54%respectively;12M-QTL were simultaneously detected in two populations.125pairs of digenic epistatic QTL (E-QTL) controlling thirteen traits were detected in three populations. Among them,65E-QTL pairs were detected in RIL population.29E-QTL pairs were detected in XSBCF1population (19E-QTL pairs were detected by using BCF1phenotypic value,10E-QTL pairs were detected by using mid-parental heterosis value).31E-QTL pairs were detected in CBBCF1population (23E-QTL pairs were detected by using BCF1phenotypic value,8E-QTL pairs were detected by using Hmp value).2.40M-QTL controlling thirteen seed production related traits were detected in RIL population, and the percentage of phenotypic variance explained by each M-QTL ranged from2%to29%with an average9.2%.65E-QTL pairs were detected, and the percentage of phenotypic variance explained by each pair of E-QTL ranged from1%to12%with an average2.9%. Although the number of E-QTL pairs is more than M-QTL, the percentage of phenotypic variance explained is very small.56.9%of65E-QTL pairs ocurred between M-QTLs. These results showed that additive effect was the primary genetic basis of thirteen seed production related traits in japonica rice.3.46M-QTL controlling thirteen seed production related traits were detected in two backcross populations. Among them,26QTL (56.5%) showed additive effect, and the percentage of phenotypic variance explained by each QTL ranged from2%to72%with an average29.9%;18(9.1%) showed overdominant effect, and the percentage of phenotypic variance explained by each QTL ranged from7%to80%with an average44%;2(4.3%) showed partial dominant effect, and the percentage of phenotypic variance explained by each QTL ranged from22%to58%with an average41%.60E-QTL pairs controlling thirteen traits were detected. Among them,42pairs (70%) showed additive x non-additive interactions effect, and the percentage of phenotypic variance explained by each pair of E-QTL ranged from6%to60%with an average22.9%;18pairs (30%) showed dominant x dominant interactions effect, and the percentage of phenotypic variance explained by each pair of E-QTL ranged from21%to83%with an average49.1%. These results showed that additive×non-additive and dominant×dominant interactions effect were the primary genetic basis of heterosis of thirteen seed production related traits in japonica rice.4. In the process main effect QTL controlling thirteen seed production related traits were mapped,14intervals controlling2or more than2traits were found. Among them, RM265-RM3482located in the interval of38041145-41246585bp in physical map on chromosome1simultaneously controlled3trais of panicle exsertion degree, difference between panicle tip and second leaf tip, length of the first internode; RM5652-RM410located the interval of13302224-17643295bp in physical map on chromosome9simultaneously controlled5traits of panicle exsertion degree, length of the first internode, flag leaf length, flag leaf area, second leaf length. The intervals controlling many traits have important significance for modifing several seed production related traits of male sterile line by Molecular Marker-assisted Selection.5.45target plants (BC3F1) of which donor segments can cover the whole genome were obtained by SSR Marker-Assisted Selection, and their proportion ranged from91.96%to99.55%(Table3-3). Among them,863C-30-20-10individual containing too many heterozygous fragments backcrossed with863B, and obtained the single-plant seeds of BC4F1; the remaining was self-crossed to obtain BC3F2single-plant seeds. The corresponding introgressed line can be selected from BC3F2family by Marker-Assisted Selection in next season.6.10plants were obtained by SSR Marker-Assisted selection basis on QTL mapping results of flag leaf angle, of which marker genotypes are both heterozygous in qFLA2and qFLA8locus. Among them,7individuals backcrossed with863B and obtained the BC4F1single-plant seeds;3individuals were self-crossed to obtain BC3F2single-plant seeds.8plants of which genotypes are heterozygous in qFLA8locus were obtained. Among them,2individuals backcrossed with863B and obtained the BC4F1single-plant seeds,6individuals were self-crossed to obtain BC3F2single-plant seeds. The BC3F2seeds of5plants of which genotypes heterozygous in qFLA2locus were obtained. Combining with phenotype and genotype identification, the corresponding863B NIL groups of big flag leaf can be selected from BC3F2family in next season. |
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