Hori Kiyosumi, Suzuki Keitaro, Ishikawa Haruka, Nonoue Yasunori, Nagata Kazufumi, Fukuoka Shuichi, Tanaka Junichi
Institute of Crop Science, NARO, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8518, Japan.
College of Agriculture, Ibaraki University, 3-21-1 Chuo, Ami, Ibaraki, 300-0393, Japan.
Rice (N Y). 2021 Jan 7;14(1):8. doi: 10.1186/s12284-020-00447-8.
In temperate rice cultivation regions, japonica rice cultivars are grown preferentially because consumers deem them to have good eating quality, whereas indica rice cultivars have high grain yields and strong heat tolerance but are considered to have poor eating quality. To mitigate the effects of global warming on rice production, it is important to develop novel rice cultivars with both desirable eating quality and resilience to high temperatures. Eating quality and agronomic traits were evaluated in a reciprocal set of chromosome segment substitution lines derived from crosses between a japonica rice cultivar 'Koshihikari' and an indica rice cultivar 'Takanari'.
We detected 112 QTLs for amylose and protein contents, whiteness, stickiness, hardness and eating quality of cooked rice grains. Almost of 'Koshihikari' chromosome segments consistently improved eating quality. Among detected QTLs, six QTLs on chromosomes 1-5 and 11 were detected that increased whiteness and stickiness of cooked grains or decreased their hardness for 3 years. The QTLs on chromosomes 2-4 were not associated with differences in amylose or protein contents. QTLs on chromosomes 1-5 did not coincide with QTLs for agronomic traits such as heading date, culm length, panicle length, spikelet fertility and grain yield. Genetic effects of the detected QTLs were confirmed in substitution lines carrying chromosome segments from five other indica cultivars in the 'Koshihikari' genetic background.
The detected QTLs were associated with differences in eating quality between indica and japonica rice cultivars. These QTLs appear to be widely distributed among indica cultivars and to be novel genetic factors for eating quality traits because their chromosome regions differed from those of the GBSSI (Wx) and SSIIa (Alk) genes. The detected QTLs would be very useful for improvement of eating quality of indica rice cultivars in breeding programs.
在温带水稻种植区，粳稻品种更受青睐，因为消费者认为其食味品质良好，而籼稻品种产量高且耐热性强，但食味品质被认为较差。为减轻全球变暖对水稻生产的影响，培育兼具理想食味品质和耐高温能力的新型水稻品种至关重要。利用粳稻品种“越光”与籼稻品种“丰锦”杂交衍生的一套相互的染色体片段代换系，对食味品质和农艺性状进行了评价。
我们检测到112个控制直链淀粉和蛋白质含量、白度、粘性、硬度以及米饭食味品质的QTL。几乎所有“越光”染色体片段都能持续改善食味品质。在检测到的QTL中，第1、5和11号染色体上的6个QTL在3年中均被检测到，它们能提高米饭的白度和粘性，或降低其硬度。第2至4号染色体上的QTL与直链淀粉或蛋白质含量的差异无关。第1至5号染色体上的QTL与抽穗期、茎长、穗长、小穗育性和产量等农艺性状的QTL不一致。在“越光”遗传背景下携带来自其他5个籼稻品种染色体片段的代换系中，证实了所检测到的QTL的遗传效应。
所检测到的QTL与籼稻和粳稻品种食味品质的差异有关。这些QTL似乎广泛分布于籼稻品种中，并且是食味品质性状的新遗传因子，因为它们的染色体区域与颗粒结合型淀粉合成酶I（Wx）基因和淀粉合成酶IIa（Alk）基因的区域不同。所检测到的QTL在育种计划中对于改善籼稻品种的食味品质将非常有用。
