1.Taihu Agricultural Research Institute of Jiangsu;2.College of Life Sciences, Huaiyin Normal University, Huai’an
The Agricultural Science And Technology Innovation Program (SNG2020048, SNG201914)， the Jiangsu University Student Innovation Program (202110323059Y)
近年来，全球低温极端气候频发，对水稻生产带来严重的影响。低温严重限制了水稻种植区域的扩大。因此，鉴定克隆水稻低温发育相关基因，阐明其分子机理，为水稻低温分子育种奠定理论基础。本研究从水稻“日本晴”化学诱变突变体库筛选鉴定到一个低温叶片白化的突变体lta1(Low temperature albinism1)。相比野生型，在20℃生长条件下，突变体lta1叶片白化，叶绿素含量显著降低，叶绿体结构发育异常；在30℃生长条件下，突变体lta1与野生型生长无显著差异。通过图位克隆将突变基因lta1定位第3号染色体短臂插入/缺失标记LTA1-3与LTA1-7之间，物理距离为132 kb。基于水稻基因表达数据库，在132 kb区间内有17个候选基因，其中有6个候选基因翻译的蛋白可能定位于叶绿体。实时荧光定量PCR结果表明多数叶绿体编码基因的表达在突变体中受到显著抑制，而多数叶绿素合成相关基因的表达未发生显著变化。本研究结果为进一步克隆LTA1基因，揭示水稻低温下叶绿体发育的机理奠定了基础。
In recent years, the global low temperature extreme weather occurs frequently, destabilizing the rice production. Low temperature is a factor that restricts the expansion of rice planting areas. Therefore, the identification and cloning of genes related to low-temperature and the elucidation of their molecular mechanism might lay a theoretical foundation in low-temperature molecular breeding of rice. In this study, a mutant lta1 (low temperature albinism 1) showing low temperature leaf albinism was identified from the chemically-induced mutagenesis mutant library of rice "Nipponbare". Compared with the wild type, the lta1 mutant displayed albino leaves with significantly reduced chlorophyll content, and abnormal chloroplast structure development at 20 ℃, whereas there was no significant difference between lta1 and wild type at 30 ℃. Through map-based cloning, the mutant gene lta1 was allocated between the insertion/deletion markers LTA1-3 and LTA1-7 on the short arm of chromosome 3, with a physical distance of 132 kb. Based on the rice gene expression database, 17 candidate genes in the region were annotated, and the proteins of six candidate genes were proposed to be localized in chloroplasts. Real-time fluorescence quantitative PCR showed that most chloroplast encoding genes were observed with lower transcripts in the mutant, while most chlorophyll synthesis related genes did not change significantly. Our results laid a foundation for further cloning the LTA1 gene and revealing the mechanism of chloroplast development in rice under low temperature.