Genetic Analysis And Gene Mapping Of A Narrow-leaf Mutant (nal(t)) In Rice (Oryza Sativa L.)

Rice (Oryza sativa L.), one of the world's most important crops, is a gramineous monocotyledons plant. The rice was planted in our country since 8000 years ago. In ancient times, human based on the wild rice to make it became half-cultivated rice and cultivated rice. Over thousands of years, the rice yield has a great progress, but it still can't be satisfied to the people. At present, improving the quality and yield of rice are still the center of rice research. Recently, Longping Yuan academician noticed that phenotype, in super hybrid rice breeding, was of important, and put the phenotype index forward breeding the super hybrid:length, straight and narrow, thick, V type of the top three leaf shape trait. This was a typical "leaf stacks" plant model, it could fully express the photosynthesis of the shrouded blade in late growth stage and increase output. The ideal phenotype is very important for improvement of the plant. In phenotype research, research of the leaf blade is the key. Researching its growth and genetic control mechanism, is very important for improvement yield and phenotype of the rice.At present, there is lot of researching phenotype of the leaf. But phenotype of the narrow leaf, proposed Longping Yuan academician, is less researched, especially in gene mapping and cloning. A narrow leaf mutant was found, which derived from Jinhui10 treated with ethyl methane sulfonate (EMS). The mutant displayed significant phenotype of narrow leaf. In order to understand the phenotype and genetic characteristics, five generations of the mutations materials was continuously inbreeded. until stable inheritance. In Chongqing, the cross combination of xinonglA x nal(t) was made in 2007 in autumn. The F₁ was planted and the F₂ was harvested in Hainan. In Chongqing, the F₂ was planted as the groups of gene mapping and analysis. 1 phenotype analysis of the nal(t)The data from wide-type and parents of nal(t), was surveyed and statisticsed on field. The mutant displayed a significant phenotype of narrow leaf, narrow and short culm and short panicle, First branch number reduced, long and short rice and yield reduced.Plant height of nal(t) was 86.10 cm, which was 86% of the wild type. It reached significant at the 0.01 level. The leaf width was 0.99 cm and 1.42 cm, respectively, at the seedling stage and the heading stage, which was 76% and 74%, respectively, that of the wild type. Both reached significant at the 0.01 level. At the heading stage, the length of the first, second and third internodes from the top was 9.16 cm,6.97 cm and 3.57 cm, respectively, accordingly up that of the wild type with 63%,83% and 71%. Narurally, so was the width,0.31 cm,0.36 cm and 0.45 cm, respectively corresponding 78%,72% and 79% of the wild type. Particularly in the first to top internode, It reached significant at the 0.01 level.Compared with the wild type, the seed setting rate of the nal(t) significantly reduced, was 66%. The grain grew narrow, was 86% of the wild type, and longer than the wild type. Spanicle length and first branch number, reached significant at the 0.01 level. 2 genetic analysis of the nal (t)XinonglA as the female and the nal(t) as the male, confected the cross combination. Individual plants in F₁ were all normal. That showed it was controlled by a recessive gene. Individual plants in F₂ showed two phenotype. One was normal. Other was mutant. Normal plants had 1966 and mutant plants had 647.χ²test showed that the separation ratio between normals and mutants fited 3:1 (χ²=0.0866<χ_0.05²=3.84), showed that it was controlled by a major recessive nuclear gene. 3 gene mapping of the nal(t)393 pairs SSR markers was chose, which evenly distribute in 12 chromosomes, in order to analyse the polymorphism between xinonglA and nal(t). The polymorphic markers had 90 pairs and the polymorphic rate was 23%. The 647 narrow leaf mutations was used in F₂ as gene mapping groups. We respectively selected the ten of normal individual plants and the ten of mutant individual plants and equivalently extracted genome DNA in order to construct the normal gene pool and the mutant gene pool. The polymorphic markers was used to amplificate between the normal gene pool and the mutant gene pool. Primers in which showed polymorphic, would be used to verify the single in F₂ population. The result showed that the NAL(T) was located in chromosome 12, linked with the RM1261 and genetic distances were 17.5 cM. Further, the simple sequence repeat(SSR) was designed primers in two sides of RM1261. At last, it was located between SSR markers RM6869 and RM28537 on the chromosome 12, with genetic distances 3.1 cM and 9.0 cM, respectively. This study lay the foundation of the fine structure gene mapping, the marker-assisted breeding, gene cloning and functional analysis.