Maipoka Maiporn, Walayaporn Kitti, Aesomnuk Wanchana, Ruengphayak Siriphat, Arikit Siwaret, Vanavichit Apichart
Rice Science Center, Kasetsart University, Nakhon Pathom, Thailand.
Department of Agronomy, Faculty of Agriculture at Kamphaeng Saen, Kasetsart University, Nakhon Pathom, Thailand.
Front Plant Sci. 2025 Aug 20;16:1622640. doi: 10.3389/fpls.2025.1622640. eCollection 2025.
Rice is mainly consumed by half of the world's population. The imminent climate change and population growth expected in the next 30 years will outpace the current rice production capacity, posing risks to food and nutrition security in developing nations. One simplified approach to address this challenge is to improve photosynthetic capacity by increasing chlorophyll content in leaves and stems.
We identified a unique white-striped leaf () mutant, RBR05, which is productive, stage-specific and temperature-sensitive, albeit with low chlorophyll content during the adult stage and recessive to regular solid-green leaf (SGL) rice. We utilised RNA sequencing between the and SGL to identify differentially expressed genes (DEGs) and QTL sequencing to identify genes responsible for the phenotype.
We identified a single recessive gene controlling in RBR05. It is a novel missense mutation (R310H) of , a key contributor to the phenotype in RBR05. The mutation, , turns Arg to His at amino acid position 310 in exon 10, which results in abnormal chloroplast development, a lack of chlorophyll pigment, and the formation of non-chlorophyllous cells in the whitened region of the leaves and leaf sheaths. The was associated with decreased gene expression in the formation of photosynthetic machinery and the chlorophyll biosynthetic pathway, while the upregulation of the and genes involved in the expression of plastid-encoded genes was observed. A SNP marker specific for the missense mutation was completely co-segregated with the in the segregating population for and SGL, demonstrating that the R310H substitution is responsible for in RBR05.
Previous reports have shown that is a hotspot of mutations, which severely affect from the seedling to heading stages. In several events, the interaction between and highlights the critical role of maintaining nucleotide homeostasis and proper chloroplast development in compensating for mutations. The functional marker developed in this study will enable rice breeders to further enhance new leaf colouration and productivity in RBR05.
全球有一半人口以大米为主食。预计未来30年即将到来的气候变化和人口增长将超过当前的水稻生产能力，给发展中国家的粮食和营养安全带来风险。应对这一挑战的一种简化方法是通过增加叶片和茎中的叶绿素含量来提高光合能力。
我们鉴定出一个独特的白条纹叶（）突变体RBR05，它具有生产力，具有阶段特异性且对温度敏感，尽管在成年期叶绿素含量较低，并且相对于常规的实心绿叶（SGL）水稻是隐性的。我们利用和SGL之间的RNA测序来鉴定差异表达基因（DEG），并通过QTL测序来鉴定导致表型的基因。
我们在RBR05中鉴定出一个控制的隐性基因。它是的一个新的错义突变（R310H），是RBR05中表型的关键贡献者。该突变，在第10外显子的氨基酸位置310处将精氨酸变为组氨酸，导致叶绿体发育异常、缺乏叶绿素色素，并在叶片和叶鞘的白化区域形成非叶绿素细胞。与光合机构形成和叶绿素生物合成途径中的基因表达降低有关，同时观察到和参与质体编码基因表达的基因上调。针对该错义突变的SNP标记在和SGL的分离群体中与完全共分离，表明R310H取代是RBR05中出现的原因。
先前的报道表明是突变热点，严重影响从幼苗期到抽穗期的。在几个事件中，和之间的相互作用突出了维持核苷酸稳态和适当叶绿体发育在补偿突变中的关键作用。本研究中开发的功能标记将使水稻育种者能够进一步提高RBR05中的新叶色和生产力。
