Bhandari Aditi, Sandhu Nitika, Bartholome Jérôme, Cao-Hamadoun Tuong-Vi, Ahmadi Nourollah, Kumari Nilima, Kumar Arvind
Rice Breeding Platform, International Rice Research Institute, DAPO Box, 7777, Metro Manila, Philippines.
Banasthali Vidyapith, Banasthali, 304022, India.
Rice (N Y). 2020 Aug 6;13(1):53. doi: 10.1186/s12284-020-00406-3.
Reproductive-stage drought stress is a major impediment to rice production in rainfed areas. Conventional and marker-assisted breeding strategies for developing drought-tolerant rice varieties are being optimized by mining and exploiting adaptive traits, genetic diversity; identifying the alleles, and understanding their interactions with genetic backgrounds for their increased contribution to drought tolerance. Field experiments were conducted in this study to identify marker-trait associations (MTAs) involved in response to yield under reproductive-stage (RS) drought. A diverse set of 280 indica-aus accessions was phenotyped for ten agronomic traits including yield and yield-related traits under normal irrigated condition and under two managed reproductive-stage drought environments. The accessions were genotyped with 215,250 single nucleotide polymorphism markers.
The study identified a total of 219 significant MTAs for 10 traits and candidate gene analysis within a 200 kb window centred from GWAS identified SNP peaks detected these MTAs within/ in close proximity to 38 genes, 4 earlier reported major grain yield QTLs and 6 novel QTLs for 7 traits out of the 10. The significant MTAs were mainly located on chromosomes 1, 2, 5, 6, 9, 11 and 12 and the percent phenotypic variance captured for these traits ranged from 5 to 88%. The significant positive correlation of grain yield with yield-related and other agronomic traits except for flowering time, observed under different environments point towards their contribution in improving rice yield under drought. Seven promising accessions were identified for use in future genomics-assisted breeding programs targeting grain yield improvement under drought.
These results provide a promising insight into the complex genetic architecture of grain yield under reproductive-stage drought in different environments. Validation of major genomic regions reported in the study will enable their effectiveness to develop drought-tolerant varieties following marker-assisted selection as well as to identify genes and understanding the associated physiological mechanisms.
生殖阶段干旱胁迫是雨养地区水稻生产的主要障碍。通过挖掘和利用适应性性状、遗传多样性，鉴定等位基因，并了解它们与遗传背景的相互作用，以增加对耐旱性的贡献，正在优化培育耐旱水稻品种的常规育种和标记辅助育种策略。本研究进行了田间试验，以鉴定与生殖阶段（RS）干旱下产量响应相关的标记-性状关联（MTA）。对280份籼稻-奥里萨稻品种进行了表型分析，测定了包括产量和产量相关性状在内的10个农艺性状，测定环境为正常灌溉条件以及两种可控生殖阶段干旱环境。利用215,250个单核苷酸多态性标记对这些品种进行基因分型。
该研究共鉴定出10个性状的219个显著MTA，并在以全基因组关联研究（GWAS）确定的SNP峰值为中心的200 kb窗口内进行候选基因分析，结果在10个性状中的7个性状的38个基因、4个先前报道的主要籽粒产量QTL和本文新发现的6个QTL内或其附近检测到这些MTA。显著MTA主要位于第1、2、5、6、9、11和12号染色体上，这些性状所捕获的表型变异百分比在5%至88%之间。在不同环境下观察到，除开花时间外，籽粒产量与产量相关性状和其他农艺性状呈显著正相关，这表明它们对干旱条件下提高水稻产量有贡献。鉴定出7个有潜力的品种，可用于未来旨在提高干旱条件下籽粒产量的基因组辅助育种计划。
这些结果为不同环境下生殖阶段干旱条件下籽粒产量的复杂遗传结构提供了有价值的见解。对本研究中报道的主要基因组区域进行验证，将有助于通过标记辅助选择培育耐旱品种，以及鉴定基因并了解相关生理机制。
