| Rice is one of the most important crops in China, and its stable and even increased yield is of great significance to food security in China. Recently, a new type rice variety which is japonica cultivars with panicle erectness (PE) appeared in high-yielding rice varieties. Studies had proved that japonica cultivars with PE traits have higher yield than ones with curved panicles in rice, so that ,in recent years, rice with PE trait become a research focus of the breeding experts and a series cultivars with PE trait have been developed through various methods.With the rapid development of molecular techniques, researches on the genetic mechanism of rice with PE trait have been focused by the geneticists. A breakthrough has been made of the japonica PE type genetic model, genetic effects, as well as the positioning of the chromosome and the gene pedigree analysis. However, the problems that how the gene controlling japonica PE trait enhances the yield and whether it can be used in indica have not been solved.In this study, DH and NILs populations were applied for research on the genetic effects of the PE trait major QTL qPE9-1.In addition,one PE mutant was isolated from 93-11 induced by 60Co-γray. Agronomic traits analysis, genetic analysis and gene targeting were conducted. The main results were follows:Part 1: study of EP QTL qPE9-1 in Japonica cultivars1 As to DH population, regression analysis of several panicle agronomic traits showed that there was significant contribution of panicle length, plant height and seed number of primary branch to panicle curvature, and the results were consistent with previous studies, and the analysis of the investigation of the internode agriculture showed that there was significant contribution of the upper two internode length to panicle curvature. It demonstrated that genes controlling panicle curvature also affected the inter-section of the plant agriculture.2 Near-isogentic Lines(NILs) of qPE9-1were constructed through molecular marker-assisted selection (MAS).The qPE9-1 from the Wuyunjing 8 was imported into the drooping panicle cultivar Nongken 57.Genetic analysis showed that qPE9-1 performed dominantly. Compared with Nongken 57, the NIL- qPE9-1 had shorter panicle length, plant height and upper three leaves length along with the panicle erect. All of the phenotypes indicated that qPE9-1is pleiotropic.Part 2: Mapping of PE gene ep-9311 in indica A new erect panicle mutant was developed by 60Co-γirradiation of an indica rice variety 9311,for the first time of its kind in indica rice.1 Analysis of agronomic traits showed that,besides the PE trait, the mutant had shortened panicle length, reduced number of the secondary branches and spikelets of secondary branches compared with its parental variety 9311.2 ep-9311 mutant was crossed to the wild-type Suyunuo, the F1 plants were of erect panicle and the ratio of normal plants to mutant plants in F2 population fitted to the ratio of 3:1, suggesting the phenotype of the ep-9311 mutant was controlled by single recessive gene.3 Based on the progenies from F2 and F3 populations of ep-9311/Suyunuo, the ep-9311 gene was restricted to a about 60-kb region on AP005198 of the long arm of chromosome 7 by several kinds of markers.
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