参与高温诱导水稻颖花开裂的互作基因HIS和HER的克隆及功能研究

Global warming is becoming a big challenge to food production due to the adverse effects on crop yield. Rice is very sensitive to high temperature, especially at booting and flowering stages. However, little knows about the underlying mechanism of how heat stress affects rice spikelets development at booting stage. Our previous study found two genetically interacted genes, HIS (Heat induced smile) and HER (HIS’ essential relative) are essential to induce the expression of hull splitting under heat stress of a CSSL (chromosome single substitution line) line, SL-14, which derived from the cross of an indica variety, Habataki, as the donor parent and a japonica variety, Sasanishiki, as the recurrent parent. The phenotype of SL-14 is similar to the cause-unknown syndromes featured as splitted hulls with abnormal seed appearance found in rice main producing area of China. We have narrowed HIS and HER down into 750 kb region on chromosome 1 and 50 kb region on chromosome 4, respectively. Here, we proposed to clone and functional characterize the causal genes of HIS and HER, and validate the physical interaction between the genes’ coding proteins. We expect that the findings may broaden our understandings of the genetic regulation of reproductive development under heat stress in rice, and provide potential target genes for breeding heat-resistant varieties.

全球变暖给世界粮食生产带来了严峻挑战。水稻在孕穗期和开花期对高温天气最为敏感，目前对水稻孕穗期耐热机制尚鲜有报道。本项目从籼稻Habataki和粳稻Sasanishiki构建的染色体片段替换系中发现一个株系SL-14在高温下颖壳不闭合。这一表型与近年来一些水稻产区生产上遇到的裂颖症状极为相似。通过遗传分析，我们发现来自Habataki的两个显性互作基因HIS (Heat induced smile)和HER (HIS’ essential relative)参与调控高温下SL-14的裂颖发生。目前我们已经将两个基因分别定位到水稻第1和第4染色体750kb和50kb的范围内。本项目拟通过对HIS和HER的图位克隆、功能分析和蛋白互作研究，揭示温度影响水稻颖花发育的分子调控机理。相关研究成果将有助于我们深入理解高温胁迫影响水稻生殖发育的作用机理，同时为今后高温育种和分子改良提供潜在靶标基因。

全球变暖给世界粮食生产带来了严峻挑战。水稻在孕穗期和开花期对高温天气最为敏感，目前对水稻孕穗期耐热机制尚鲜有报道。本项目从籼稻Habataki和粳稻Sasanishiki构建的染色体片段替换系中发现一个株系SL-14在高温下颖壳不闭合。这一表型与近年来一些水稻产区生产上遇到的裂颖症状极为相似。通过遗传分析，我们证明了来自Habataki的两个显性互作基因HIS (Heat induced smile)和HER (HIS’ essential relative)参与调控高温下SL-14的裂颖发生。目前我们已经将两个基因分别定位到水稻第1和第4染色体132kb和47kb的范围内。我们的结果表明，SL-14的裂颖表型受环境温度调控，将孕穗期温度设定为恒定的29度时即可诱导出现裂颖表型；并且这种发育异常并不是开花后发生的，而是在幼穗发育的第7期就表现出来。通过RNA-seq对SL-14和对照Sasanishiki的幼穗进行转录组分析，发现和常温条件相不，MADS家族转录因子的表达在SL-14中发生了变化，但是并不直接参与调控裂颖表型的发生。同时我们发现直接参与颖壳发育的一些基因，如OsGRF6、OsCR4、OsIG1以及Obp等在SL-14中的表达受到抑制。OsbZIP76是一个幼穗中差异表达基因，通过构建RNAi、过量表达和CRISPR/Cas9敲除突变体等遗传材料，我们对基因的功能进行了分析。该基因并不直接参与裂颖调控，但是能够和一个NF-YB转录因子家族成员OsNF-YB1互作，调控水稻种子的发育。