Table_2_Multiple Small-Effect Alleles of Indica Origin Enhance High Iron-Associated Stress Tolerance in Rice Under Field Conditions in West Africa.docx

Understanding the genetics of field-based tolerance to high iron-associated (HIA) stress in rice can accelerate the development of new varieties with enhanced yield performance in West African lowland ecosystems. To date, few field-based studies have been undertaken to rigorously evaluate rice yield performance under HIA stress conditions. In this study, two NERICA × O. sativa bi-parental rice populations and one O.sativa diversity panel consisting of 296 rice accessions were evaluated for grain yield and leaf bronzing symptoms over multiple years in four West African HIA stress and control sites. Mapping of these traits identified a large number of QTLs and single nucleotide polymorphisms (SNPs) associated with stress tolerance in the field. Favorable alleles associated with tolerance to high levels of iron in anaerobic rice soils were rare and almost exclusively derived from the indica subpopulation, including the most favorable alleles identified in NERICA varieties. These findings highlight the complex genetic architecture underlying rice response to HIA stress and suggest that a recurrent selection program focusing on an expanded indica genepool could be productively used in combination with genomic selection to increase the efficiency of selection in breeding programs designed to enhance tolerance to this prevalent abiotic stress in West Africa.

解析水稻田间耐高铁关联胁迫（high iron-associated, HIA）的遗传机制，可加速西非低洼生态系统中产量表现优异的水稻新品种培育。迄今为止，针对高铁关联胁迫环境下水稻产量表现开展的严谨田间研究仍较为匮乏。本研究针对两个NERICA×栽培稻（Oryza sativa, O. sativa）双亲本分离群体以及一个包含296份水稻种质的栽培稻多样性面板，于西非4处高铁关联胁迫试验点及对照点开展多年份的籽粒产量与叶赤枯症状评估。对上述性状开展定位分析后，共鉴定出大量与田间耐胁迫相关的数量性状位点（quantitative trait locus, QTL）与单核苷酸多态性（single nucleotide polymorphisms, SNPs）。与厌氧水稻土壤高铁耐性相关的有利等位基因较为稀有，且几乎全部源自籼稻亚种，其中包括在NERICA品种中鉴定出的最优耐性等位基因。本研究结果揭示了水稻响应高铁关联胁迫的复杂遗传调控基础，并提出：针对扩大籼稻基因库开展的轮回选择项目，结合基因组选择技术，可有效提升西非地区针对该普遍非生物胁迫的耐逆育种选择效率。