To understand the mechanisms of cadmium (Cd) tolerance during seed germination in rice, quantitative trait loci (QTLs) and epistasis were analyzed using 124 rice backcross recombinant inbred lines (BRILs) derived from a cross between indica CH891 and japonica 02428, and six additive QTLs along with 16 pairs of epistatic QTLs involving 17 loci were identified for germination rate (GR) under Cd and control conditions. The expression of these QTLs and their epistasis under Cd stress and control conditions were not the same, and more pairs of epistatic QTLs were detected under Cd stress than under control conditions, suggesting that Cd stress could induce a different gene expression network and that Cd tolerance with respect to GR is controlled by additive effects and gene interactions. To our knowledge, this is the first study of rice seed germination ability under Cd stress in a typical indica/japonica cross. Notably, all the major additive QTLs for GR were mapped to a small chromosomal region (60–980 kb). These QTLs could be highly valuable genetic factors for cadmium tolerance improvement in rice lines. Moreover, the BRILs developed in this study will serve as an appropriate choice for mapping and studying the genetic basis of complex traits in rice.

中文翻译：

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与水稻种子萌发能力相关的镉 (Cd) 耐受性的加成和上位 QTL

为了了解水稻种子萌发过程中镉 (Cd) 耐受性的机制，使用源自籼型 CH891 和粳型 02428 杂交的 124 个水稻回交重组自交系 (BRIL) 和六个添加剂分析了数量性状位点 (QTL) 和上位性。 QTL 以及涉及 17 个基因座的 16 对上位 QTL 在 Cd 和对照条件下的发芽率 (GR) 被鉴定。这些QTL在Cd胁迫和对照条件下的表达及其上位性并不相同，在Cd胁迫下检测到的上位QTL对比对照条件下多，表明Cd胁迫可以诱导不同的基因表达网络和Cd耐受性GR 受累加效应和基因相互作用控制。据我们所知，这是对典型籼粳杂交水稻种子在镉胁迫下发芽能力的首次研究。值得注意的是，GR 的所有主要附加 QTL 都被定位到一个小的染色体区域 (60-980 kb)。这些 QTL 可能是水稻品系耐镉性提高的非常有价值的遗传因子。此外，本研究中开发的 BRIL 将作为绘制和研究水稻复杂性状遗传基础的合适选择。