作者机构：
[Huang, Ming; Chen, Zhi-qiang] South China Agr Univ, Natl Engn Res Ctr Plant Space Breeding, Guangzhou 510642, Guangdong, Peoples R China.;[Chen, Li-yun] Hunan Agr Univ, Rice Res Inst, Changsha 410128, Hunan, Peoples R China.;[Huang, Ming] South China Agr Univ, Natl Engn Res Ctr Plant Space Breeding, Rm 713,Sci&Tec Bldg,483 Wushan Rd, Guangzhou 510642, Guangdong, Peoples R China.
通讯机构：
[Huang, Ming] S;South China Agr Univ, Natl Engn Res Ctr Plant Space Breeding, Rm 713,Sci&Tec Bldg,483 Wushan Rd, Guangzhou 510642, Guangdong, Peoples R China.
关键词：
Rice;Heterosis;General combining ability;Specific combining ability;Effective-increasing loci;Effective-decreasing loci
摘要：
Diallel crosses have been widely used for analysis of general combining ability (GCA), specific combining ability (SCA) and heterosis. In the present research, 12 lines were selected from 60 inbred rice bred by International Rice Research Institute with extremely-high or -low yielding records according to the previous three consecutive seasons of yield trial experiments, to construct a half diallel cross. The genetic distances (GDs) revealed by molecular markers for the 12 lines ranged from 0.2288 to 0.7169, averaging at 0.5882; clustering analysis showed the 12 lines were divided into four groups maintaining the original cluster structure of the 60 lines. The positive loci (PLs) including effective-increasing loci (ILs) and effective-decreasing loci (DLs) were screened. The results showed that hybrids derived from those parents with higher GCA effects had better performance for traits of yield and yield components. The SCA effects were strongly correlated to F1 performance as well as heterosis; the GDs based on ILs were significantly positive correlated to SCA effects and heterosis for yield and yield components while the GDs based on DLs showed the significant negative correlations. Based on this research, a new conception, i.e. general sum of combining ability (GSCA) was conceived, which is defined as the sum of GCAs for two parents of a hybrid. The GSCA and SCA showed similar correlations with traits of yield and yield components. The results illustrated that ILs could be used for further study on prediction of heterosis for traits of yield and yield components; and GSCA may be another considerable parameter combined with ILs for breeders in selecting elite hybrid.
关键词：
Two-line hybrid rice;Dual-purpose genic male sterile line;Safety of seed production
摘要：
The insecure problems of seed production have seriously hampered the healthy and sustainable development of two-line hybrid rice.The safety issues on seed production of two-line hybrid rice and current research situation were pointed out in this paper.The three main reasons for unsafety in seed production of twoline hybrid rice were unsuitable site selection,high critical sterility-inducing temperature and the drift of critical temperature.In this paper,strategies and measures were put forward based on many years of practice.It could minimize the risk in seed production of two-line hybrid rice by selecting dual-purpose genic male sterile line with lower critical sterility-inducing temperature and long lower temperature resistant time.Based on the climate data and climatic demands of the ＂three safe-periods＂ in seed production,a new idea for determining appropriate bases and periods for seed production was proposed by using computer technology,which solved the aimless selection of sites and periods for the seed production of two-line hybrid rice.Besides,we established a system of single plant selection and identification method and original seed propagation with cyclic cold water,which could reduce the generation number of original seed propagation in seed production and avoid the drift of critical sterility-inducing temperature.This paper improved the seed production safety in the three aspects of seed nature,seed source and seed production site.
摘要：
<jats:title>Abstract</jats:title><jats:p>Two‐line hybrid rice as a novel hybrid breeding method has huge potential for yield increasing and utilization of intersubspecific heterosis, and it is of major significance for the food security of rice‐consuming populations. Zhu1S is a thermosensitive genic male‐sterile line of rice with low critical temperature and excellent combining ability, which has been widely exploited as a female parent in Chinese two‐line hybrid rice breeding. Here, genetic mapping in F<jats:sub>2</jats:sub> populations was used to show that its male sterility is inherited as a single recessive gene and that responsible gene (termed <jats:styled-content style="fixed-case"><jats:italic>tms9</jats:italic></jats:styled-content>) lies on the short arm of chromosome 2. A high‐resolution linkage analysis which was based on the Zhu1S/R173 F<jats:sub>2</jats:sub> population found that the thermosensitive genic male‐sterile gene <jats:italic>tms9</jats:italic> of Zhu1S was fine mapped between insertion–deletion (Indel) markers Indel 37 and Indel 57, and the genetic distance from the <jats:styled-content style="fixed-case"><jats:italic>tms9</jats:italic></jats:styled-content> to the two markers was 0.12 and 0.31cM, respectively. The physical distance between the two markers was about 107.2kb. Sequence annotation databases showed that the two Indel markers (Indel 37 and Indel 57) were located on two <jats:styled-content style="fixed-case">BAC</jats:styled-content> clones (B1307A11 and P0027A02). There are sixteen open reading frames (<jats:styled-content style="fixed-case">ORF</jats:styled-content>) present in this region. The results of this study are of great significance for further cloning <jats:styled-content style="fixed-case"><jats:italic>tms9</jats:italic></jats:styled-content> and molecular marker–assisted selection.</jats:p>
作者机构：
[Zhong-hua SHENG; Li-yun CHEN] Rice Research Institute, Hunan Agricultural University, Changsha 410128, China;[Xiang-jin WEI; Gao-neng SHAO; Jian SONG; Ju LUO; Pei-song HU; Shao-qing TANG] China National Rice Research Institute, Hangzhou 310006, China
通讯机构：
Rice Research Institute, Hunan Agricultural University, China
摘要：
A new white striped leaf mutant wsl1 was discovered from Nipponbare mutated by ethyl methanesulfonate. The mutant showed white striped leaves at the seedling stage and the leaves gradually turned green after the tillering stage. The chlorophyll content of wsl1 was significantly lower than that of wild-type during the fourth leaf stage, tillering stage and booting stage. The numbers of chloroplast, grana and grana lamella were reduced and the thylakoids were degenerated in wsl1 compared with wild type. Genetic analysis showed that the wsl1 was controlled by a single recessive gene. Molecular mapping of the wsl1 was performed using an F2 population derived from wsl1/Nanjing 11. The wsl1 was finally mapped on the telomere region of chromosome 9 and positioned between simple sequence repeat markers RM23742 and RM23759 which are separated by approximately 486.5 kb. The results may facilitate map-based cloning of wsl1 and understanding of the molecular mechanism of the regulation of leaf-color by WSL1 in rice.
