Vinarao Ricky, Proud Christopher, Snell Peter, Fukai Shu, Mitchell Jaquie
School of Agriculture and Food Sciences, The University of Queensland, Brisbane, QLD, Australia.
Department of Primary Industries, Yanco Agricultural Institute, Yanco, NSW, Australia.
Front Plant Sci. 2022 Apr 29;13:873677. doi: 10.3389/fpls.2022.873677. eCollection 2022.
Aerobic rice production (AP) consumes less water compared to flooded systems. Developing genotypes and identifying genomic regions associated with low temperature (LT) tolerance at the young microspore stage (YMS) is imperative for AP, particularly for temperate regions. Using a recombinant inbred line population derived from the Australian LT tolerant variety Sherpa, experiments were conducted to map and dissect quantitative trait loci (QTL) associated with spikelet sterility (SS) after exposure to LT and to investigate floral traits contributing to the development of lower SS. Significant genotypic variation for SS was observed in the population after exposure to LT at YMS. Three genomic regions associated with SS, , , and were identified in chromosomes 3, 4, and 8 respectively, using multiple QTL models explaining 22.4% of the genotypic variation. Introgression of the favorable allele from was estimated to reduce SS by up to 15.4%. A co-locating genomic region with , was identified as the major QTL affecting days to heading and explained as much as 44.7% of the genotypic variation. Whole-genome sequence and bioinformatic analyses demonstrated as the candidate gene for and to our knowledge, this was the first attempt in connecting the role of in both LT and flowering in rice. Differential sets selected for extreme SS showed LT tolerant genotype group produced higher total pollen per spikelet resulting in a higher number of dehisced anthers and pollen on stigma and eventually, lower SS than THE sensitive group. The relationship between these key floral traits with SS was induced only after exposure to LT and was not observed in warm ideal temperature conditions. Identification of elite germplasm with favorable QTL allele and combinations, gene cloning, and pyramiding with additional high-value QTL for key traits should empower breeders to develop AP adapted genotypes for temperate growing regions, and ultimately produce climate-resilient rice.
与淹水种植系统相比，旱稻生产耗水量更少。对于旱稻生产，尤其是在温带地区，培育基因型并鉴定与小孢子幼龄期（YMS）耐低温（LT）相关的基因组区域至关重要。利用源自澳大利亚耐低温品种夏尔巴的重组自交系群体，开展实验以定位和剖析与低温处理后小穗不育（SS）相关的数量性状基因座（QTL），并研究有助于降低小穗不育率的花部性状。在小孢子幼龄期经低温处理后，群体中观察到小穗不育存在显著的基因型变异。使用多个QTL模型，分别在第3、4和8号染色体上鉴定出3个与小穗不育相关的基因组区域，这些模型解释了22.4%的基因型变异。估计导入来自该区域的有利等位基因可使小穗不育率降低多达15.4%。一个与该区域共定位的基因组区域被确定为影响抽穗天数的主要QTL，解释了高达44.7%的基因型变异。全基因组序列和生物信息学分析表明该区域的候选基因，据我们所知，这是首次尝试将该基因在水稻耐低温和开花中的作用联系起来。为极端小穗不育选择的差异集表明，耐低温基因型组每个小穗产生的总花粉量更高，导致开裂花药数量更多，柱头上的花粉更多，最终小穗不育率低于敏感组。这些关键花部性状与小穗不育之间的关系仅在低温处理后才显现，在温暖的理想温度条件下未观察到。鉴定具有有利QTL等位基因和组合的优良种质、基因克隆以及与关键性状的其他高价值QTL聚合，应能使育种者培育出适合温带种植区的旱稻基因型，并最终培育出适应气候变化的水稻。
