Global warming is a major abiotic stress factor, which limit rice production. Exploiting the genetic basis of the natural variation in heat resistance at different reproductive stages among diverse exotic Oryza germplasms can help breeding heat-resistant rice cultivars. Here, we identified a stable quantitative trait locus (QTL) for heat tolerance at the heading stage on chromosome 5 (qHTH5) in O. rufipogon Griff. The corresponding gene, HTH5, pertains to the pyridoxal phosphate-binding protein PLPBP (formerly called PROSC) family, which is predicted to encode pyridoxal phosphate homeostasis protein (PLPHP) localized to the mitochondrion. Overexpression of HTH5 increased the seed-setting rate of rice plants under heat stress at the heading stage, whereas suppression of HTH5 resulted in greater susceptibility to heat stress. Further investigation indicated that HTH5 reduces reactive oxygen species accumulation at high temperatures by increasing the heat-induced pyridoxal 5'-phosphate (PLP) content. Moreover, we found that two SNPs located in the HTH5 promoter region are involved with its expression level and associated with heat tolerance diversity. These findings suggest that the novel gene HTH5 might have great potential value for heightening rice tolerance to heat stress to the on-going threat of global warming.

中文翻译：

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来自野生稻 Oryza rufipogon Griff. 的 HTH5 的自然变异与抽穗期的高温耐受性有关

全球变暖是一个主要的非生物胁迫因素，它限制了水稻的生产。利用不同外来稻种质在不同生殖阶段耐热性自然变异的遗传基础，有助于培育耐热水稻品种。在这里，我们在O的第 5 号染色体 ( qHTH5 ) 的抽穗期鉴定了一个稳定的耐热性数量性状基因座 (QTL) 。rufipogon格里夫。相应的基因HTH5属于磷酸吡哆醛结合蛋白 PLPBP（以前称为 PROSC）家族，预计其编码定位于线粒体的磷酸吡哆醛稳态蛋白（PLPHP）。HTH5的过表达 在抽穗期增加了热胁迫下水稻的结实率，而抑制HTH5 则导致对热胁迫的敏感性更高。进一步的研究表明，HTH5通过增加热诱导的 5'-磷酸吡哆醛 (PLP) 含量来减少高温下活性氧的积累。此外，我们发现位于HTH5启动子区域的两个 SNP 与其表达水平有关，并与耐热多样性有关。这些发现表明，新基因HTH5可能对提高水稻对热胁迫的耐受性以应对全球变暖的持续威胁具有巨大的潜在价值。