Crop Improvement Division, ICAR-National Rice Research Institute, Cuttack, Odisha, India.
Department of Bio-Science and Bio-Technology, Fakir Mohan University, Balasore, Odisha, India.
PLoS One. 2021 Mar 1;16(3):e0246232. doi: 10.1371/journal.pone.0246232. eCollection 2021.
Iron (Fe) toxicity is a major abiotic stress which severely reduces rice yield in many countries of the world. Genetic variation for this stress tolerance exists in rice germplasms. Mapping of gene(s)/QTL controlling the stress tolerance and transfer of the traits into high yielding rice varieties are essential for improvement against the stress. A panel population of 119 genotypes from 352 germplasm lines was constituted for detecting the candidate gene(s)/QTL through association mapping. STRUCTURE, GenAlEx and Darwin softwares were used to classify the population. The marker-trait association was detected by considering both the Generalized Linear Model (GLM) and Mixed Linear Model (MLM) analyses. Wide genetic variation was observed among the genotypes present in the panel population for the stress tolerance. Linkage disequilibrium was detected in the population for iron toxicity tolerance. The population was categorized into three genetic structure groups. Marker-trait association study considering both the Generalized Linear Model (GLM) and Mixed Linear Model (MLM) showed significant association of leaf browning index (LBI) with markers RM471, RM3, RM590 and RM243. Three novel QTL controlling Fe-toxicity tolerance were detected and designated as qFeTox4.3, qFeTox6.1 and qFeTox10.1. A QTL reported earlier in the marker interval of C955-C885 on chromosome 1 is validated using this panel population. The present study showed that QTL controlling Fe-toxicity tolerance to be co-localized with the QTL for Fe-biofortification of rice grain indicating involvement of common pathway for Fe toxicity tolerance and Fe content in rice grain. Fe-toxicity tolerance QTL qFeTox6.1 was co-localized with grain Fe-biofortification QTLs qFe6.1 and qFe6.2 on chromosome 6, whereas qFeTox10.1 was co-localized with qFe10.1 on chromosome 10. The Fe-toxicity tolerance QTL detected from this mapping study will be useful in marker-assisted breeding programs.
铁（Fe）毒性是一种主要的非生物胁迫，它严重降低了世界上许多国家的水稻产量。在水稻种质资源中存在对这种胁迫耐受性的遗传变异。对控制胁迫耐受性的基因/数量性状位点（QTL）进行定位，并将这些性状转移到高产水稻品种中，对于改善这种胁迫至关重要。通过关联作图，从 352 个种质系中构建了一个由 119 个基因型组成的作图群体，以检测候选基因/QTL。STRUCTURE、GenAlEx 和 Darwin 软件用于对群体进行分类。通过考虑广义线性模型（GLM）和混合线性模型（MLM）分析，检测标记与性状的关联。在作图群体中观察到基因型对胁迫耐受性存在广泛的遗传变异。在该群体中检测到铁毒性耐受性的连锁不平衡。该群体被分为三个遗传结构组。同时考虑广义线性模型（GLM）和混合线性模型（MLM）的标记与性状关联研究表明，叶片黄化指数（LBI）与标记 RM471、RM3、RM590 和 RM243 显著相关。检测到三个控制铁毒性耐受性的新 QTL，并将其命名为 qFeTox4.3、qFeTox6.1 和 qFeTox10.1。在本研究中，使用这个作图群体验证了先前在第 1 号染色体标记区间 C955-C885 上报道的一个 QTL。本研究表明，控制铁毒性耐受性的 QTL 与水稻籽粒铁生物强化的 QTL 紧密连锁，表明铁毒性耐受性和水稻籽粒铁含量涉及共同途径。铁毒性耐受性 QTL qFeTox6.1 与第 6 号染色体上的粒铁生物强化 QTL qFe6.1 和 qFe6.2 紧密连锁，而 qFeTox10.1 与第 10 号染色体上的 qFe10.1 紧密连锁。本研究中检测到的铁毒性耐受性 QTL 将有助于标记辅助育种计划。
