剑叶是水稻主要的源器官,剑叶大小与产量呈极显著的正相关,揭示剑叶大小和单株产量的遗传基础对于选育株型适宜的水稻高产品种具有重要意义.本研究以来源广泛、多样性丰富的1016份全球水稻核心种质资源为材料,在湖北荆州连续两年考察了种质资源的剑叶大小和单株产量.结果 显示,剑叶长、宽、面积和单株产量在两年变异丰富,受环境影响大;剑叶长、宽和面积与单株产量相关性程度较低,说明这些性状的遗传基础不同.利用4.8M高密度SNP基因型数据进行全基因组关联分析,共定位到31个影响水稻剑叶相关性状和单株产量的QTL,其中1个QTL(qFLW4)在两年均定位到,3个位点同时影响多个性状(qFLW4和qFLA4、qFLL6和qFLA6、qFLL10.1和qFLA10).结合候选区间单倍型分析和生物信息学分析,鉴定到7个候选基因和10个有利等位基因.研究结果为克隆水稻剑叶性状新基因和通过分子标记辅助选择配置不同剑叶相关基因塑造理想株型提供基因资源.

Grain shape is a very important goal in the rice breeding program nowadays. Underlying the genetic basis of grain shape would largely speed the breeding process. In the present study, a diverse panel of 1016 rice accessions from 70 countries and areas worldwide were evaluated for their grain shapes. There were large variations for all three grain shape traits, including grain length, grain width and length to width ratio, and they had significantly positive or negative correlations with each other. Besides, high positive correlations were found between two experimental years. Genome-wide association mapping strategy was conducted to identify QTL for grain shape using 509219 high quality SNP genotypes and grain shape traits. A total of 70 QTL were identified in all chromosomes. Among them, 16 QTL were found on chromosome 1, 2, 3, 5, 7, 9 and 11 expressed in both years. Eight genomic regions on chromosome 1, 3, 4, 5, 7 and 9 had pleiotropic effects on two or three traits. Four genomic regions on chromosome 3, 5, 6 and 7 were identified in both year and controlled more than two traits. Besides, 25 QTL on all chromosomes except chromosome 8, 10 and 12 had large effect on the traits. In conclusion, these results helped us better understand the genetic basis of rice grain shape and provide valuable gene resources for improving rice grain for desired shape. (C) 2020 Friends Science Publishers

利用籼粳亚种间杂种优势是水稻育种的一个重要方向,02428是一个携带有广亲和基因并表现为广亲和的粳稻,是选育籼粳杂交稻的骨干亲本.但其品质低劣,阻碍了它在育种中的应用.本研究以三系恢复系明恢63为供体,通过回交育种的方法改良02428的垩白性状.回交2代再自交8代后,从中选育出8个垩白性状明显改良的家系,其中有2个家系达到国标三级,3个家系达到国标二级;4个改良家系的产量相关性状均得到了明显提高.这些改良系为选育籼粳杂交稻提供了很高价值的亲本资源.

Excellent rice germplasm is the precondition of rice breeding. In this paper, 1 219 worldwide rice germplasm introduced from Chinese Academy of Agricultural Sciences was evaluated its adoptability in Jingzhou City and screened for high yield germplasm. The results showed that the yield and its related traits varied largely.Among them,panicle length and yield per plant had large varia-tion, while heading date, flag leaf width, number of primary branch, seed setting rate and 1 000 grain weight had small variation. Through screening 539 germplasm were adopted the ecological condition in Jingzhou, and 100 were high yield germplasm. Among them 24 were big panicle type,3 were big grain type and 23 were high seed setting rate type,respectively. They can provide valuable resources in high yield breeding of rice.

Rice yield is a complex trait that is the major target in rice breeding program. In the present study, two sets of introgression line populations derived from three parents were used to dissect the genetic basis of yield-related traits, explore the genetic background effect on QTL detection and mine pleiotropic QTL for yield-related traits.. Among the three parents, IR75862 was the common donor parent, and Ce258 and Zhongguangxiang1 were two recipient parents. The two introgression line populations were evaluated for yield-related traits in the summer of 2012 at Jingzhou, China. Combined with genotype of the introgression lines, 35 QTLs were detected in all 12 chromosomes except chromosome 5 for eight yield-related traits, including plant height, panicle number per plant, panicle length, filled grain number per panicle, spikelet number per panicle, seed setting rate, thousand grain weight and grain yield per plant, which explained 6.36. - 36.37% of phenotypic variances. No common QTL was detected in the two backgrounds, and seven chromosome regions on chromosomes 2, 3, 4, 6 and 10 had pleiotropic effects on two or more traits, indicating large genetic background effect on expression of QTLs for yield-related traits. Total of 19 (54%) QTLs including newly identified QTLs, qGY3, qFGN10.2 and qSN10 with IR75862 alleles increased yield-related traits. Therefore, it's possible to develop new super rice varieties through introgressing or pyramiding the IR75862 alleles at the pleiotropic QTLs (qPL2.1 and qPL6.1) and novel QTLs (qGY3, qFGN10.2 and qSN10) into Ce258 and Zhongguangxiang1 by marker-assisted selection. (c) 2018 Friends Science Publishers

Photosynthesis provides food and energy for all organisms on Earth, but their genetic basis particularly in rice panicle is unknown. In this study, the characterization of GZ-wp, a new rice white panicle mutant from the progeny of indica thermosensitive genic male sterile line Guangzhan 63-4S (GZ63-4S) with seeds treated by ethylmethane sulfonate was described. The results showed white panicle at heading stage and normal phenotype in other organs at whole developing stages, and some yield related traits decreased. Chlorophyll content accumulation reduced in GZ-wp. Transmission electron microscopy analysis suggested normal chloroplast structure but decreased chloroplast numbers. Genetic analysis indicated the white panicle was controlled by two independent recessive nuclear genes with duplicated effect, designed as wp5 and wp6. Finally, wp5 and wp6 were fine mapped to 211 kb and 175 kb regions on chromosome 1 and 7, respectively. The present results will facilitate the cloning of these two genes and help in understanding the genetic basis of chloroplast development in rice panicle. (C) 2018 Friends Science Publishers

Rice yield is a typical quantitative trait that is hard to improve. In this study, Minghui 63 and 02428 was used to develop reciprocal introgression lines, and they were constructed a high density Bin map by re-sequecing. The reciprocal introgression lines were planted in the summer season of 2014 at Jingzhou, China, and measured ten yield related traits including panicle number per plant, grain number per panicle, 1000-grain weight, yield per plant, heading date, plant height, panicle length, primary branch number per panicle, spikelet number per panicle and seed setting ratio. A total of 24 main-effect QTL and 97 epistatic QTL pairs were detected for yield related traits, explaining 0.9-37.0% of phenotypic variations, and epistatic QTL pairs had larger effect than main-effect QTL. Among them, two main-effect QTL (16.7%) were identified at both genetic backgrounds, indicating large background effect on QTL mapping. Moreover, no epistatic QTL pair was detected at both backgrounds, suggested that they were more sensitive to genetic background than main-effect QTL. A background independent main-effect in 7.3-7.6 Mb on chromosome 9 (qSN9) was validated for spikelet number per panicle by using introgression line, indicating it was genetically true. Our results will give us useful gene resources to improve rice yield in marker-assisted selection. (C) 2018 Friends Science Publishers

A novel QTL cluster for appearance quality on Chr07 was identified using reciprocal introgression populations in different locations in China. Two secondary F (2) populations validated QTL with significant effect on appearance quality.Appearance quality (AQ) is the main determinants of market value of rice. Identification of QTL affecting AQ is the prerequisite for efficient improvement of AQ through marker-assisted selection (MAS). Two sets of reciprocal introgression lines derived from indica Minghui 63 and japonica 02428 were used to dissect the stability of QTL affecting five AQ traits, including grain length, grain width, length to width ratio, percentage of grains with chalkiness, and degree of endosperm chalkiness using 4568 bin genotype produced from 58,000 SNPs across five different environments. A total of 41 and 30 main-effect QTL were identified in MH63 and 02428 backgrounds, respectively. Among them, 9 background-independent QTL (BI-QTL) were found. There were also 13 and 10 stable-expressed QTL (SE-QTL) across at least two environments in MH63 and 02428 backgrounds, respectively. Two important BI- and SE-QTL regions (BISERs) including BISER-I harboring qPGWC5, qDEC5, qGW5.1, and qLWR5 on chromosome 5 and BISER-II harboring qGL7, qLWR7, qPGWC7, and qDEC7 on chromosome 7 were identified. The BISER-II was newly reported and validated by two secondary F-2 populations in the reciprocal backgrounds. Among 59 epistatic QTL (E-QTL) detected in this study, there were only four SE- but no BI-E-QTL detected in different environments, indicating that genetic background has stronger effect on AQ traits than the environmental factors, especially for percentage of grains with chalkiness (PGWC) and degree of endosperm chalkiness (DEC) with lower heritability. BISER-I and BISER-II harboring many BI- and SE-QTL with favorable alleles from slender grain rice are much important for improvement of rice AQ by MAS.

Grain shape determines both appearance quality and grain yield. In this study, two sets of introgression line populations derived from three parents were used to dissect the genetic basis of grain shape and illustrate the genetic background effects on QTL expression. Among the three parents, IR75862 was the common donor parent, and Ce258 and Zhongguangxiangl were two recipient parents. The two introgression line populations were evaluated for grain shape traits in the summer of 2012 at Jingzhou, China. A total of 23 QTLs were detected in all 12 chromosomes except chromosome 1, 3 and 9 for grain length, grain width, grain thickness and length to width ratio, 11 and 12 detected in Ce258 and Zhongguangxiangl background, respectively. They explained 6.95-38.27% of phenotypic variation. Among these QTLs, only three (26%) named qGL8, qLWR5 and qLWR10 stably expressed in both genetic backgrounds, clearly indicating that genetic background had large effects on QTL expression for grain shape. IR75862 alleles at these QTLs decreased GL and LWR in both backgrounds. Our findings will facilitate the gene cloning and breeding application for improvement of grain yield and quality in future. (C) 2017 Friends Science Publishers

从国际水稻研究所引进了一套籼稻微核心种质,对其中25份种质资源进行了富硒处理并考察了外观品质.结果表明,与对照相比,富硒处理对粒型基本没有影响,但能明显降低籼稻的垩白粒率与垩白度.但是不同品种的垩白性状对富硒处理的反应差异较大,在富硒处理条件下,垩白粒率与垩白度提高的品种有7个,降低的有17个.因此,在大面积生产富硒水稻时应先筛选在富硒条件下垩白粒率和垩白度不提高的品种.

硒是人体必需的微量元素,中国大部分地区都为缺硒地带.富硒大米是人体补充硒元素的最简便的途径之一,但是富硒对水稻加工品质的影响不明.从国际水稻所引进了一套籼稻微核心种质,对其中25份种质资源在富硒条件下考察了加工品质.结果显示,不同品种对富硒的反馈表现不同,富硒分别提高了8个品种的糙米率、12个品种的精米率和10个品种的整精米率,同时降低了7个品种的糙米率、8个品种的精米率和8个品种的整精米率.富硒对糙米率和整精米率的提高和降低作用相当,能提高大部分品种的精米率.研究结果将为富硒大米育种和生产提供理论指导.

在介绍水稻加工品质各个评价指标定义的基础上，综述了各指标之间的相关性及其与其他品质性状间的相关性、水稻加工品质的遗传学基础、QTL定位及基因克隆的研究进展，可为分子标记辅助选择培育加工品质优良的水稻高产新品种提供参考。

In order to dissect the genetic bases and mine novel alleles of grain chalkiness in indica, we conducted an experiment with genome-wide association analysis using phenotypic data collected from multiple locations (Sanya of Hainan, Shenzhen of Guangdong, Hangzhou of Zhejiang, and Jingzhou of Hubei) and 6704 re-sequenced SNP markers distributed in whole genome for 272 indica mini-core germplasm collected worldwide. All accessions were classified into three subpopulations based on SNP data. Total of 42 and 44 loci were detected as significant associations with percentage of grains with chalkiness (PGWC) and degree of endosperm chalkiness (DEC), respectively, which distributed all over the 12 chromosomes. Twenty one and nineteen loci were stably expressed for PGWC and DEC in multiple locations, respectively, and 12 simultaneously affected the two traits. Eleven of the said loci were co-located in the same or near regions harboring the quality genes cloned previously. Of them, the region of 3.3–5.3 Mb on chromosome 5 was significantly associated with PGWC at all four locations, having the largest phenotypic contri-bution detected in Hangzhou location, and the carrier variety with the best favorable allele was IRGC121689;another region of 17.5–22.7 Mb on chromosome 12 was significantly associated with DEC at Sanya and Hangzhou, having the largest phenotypic contribution detected in Sanya, and the carrier variety with the best favorable allele was IRGC122285. These loci and germplasms are important potential genes and variety resources that can be used in molecular breeding for rice appearance quality.

综述了水稻株高的遗传学基础、QTL定位、精细定位及株高基因克隆的研究进展，可为分子标记辅助选择培育适宜高度的水稻高产新品种提供参考。