Evaluation of Domestication Loci Associated with Awnlessness in Cultivated Rice, Oryza sativa
Evaluation of Domestication Loci Associated with Awnlessness in Cultivated Rice, Oryza sativa
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DOI：
10.1186/s12284-020-00386-4
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发表时间：
2020-04-28
期刊：
影响因子：
5.5
通讯作者：
Ishii, Takashige
中科院分区：
文献类型：
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作者：
Amarasinghe, Yaddehige Priya Jayantha;Kuwata, Rie;Ishii, Takashige
背景 芒是位于颖片尖端的鬃毛状器官。野生稻保持着长芒，以便通过种子传播来成功繁殖种子。种子遮篷是水稻驯化过程中一个有趣的特征。在驯化的初始阶段，长芒可能对种子采集者有利。然而，最好在后期选择不落粒植物的无芒表型。调查与栽培稻无芒相关的驯化位点将有助于阐明水稻驯化的过程和历史。结果 使用水稻 IR36（具有无芒表型的栽培供体亲本）和普通野生稻 W630（具有芒的野生轮回亲本）之间的 BC3F2 群体进行了种子芒的数量性状位点 (QTL) 分析。结果，检测到4号染色体上的2个QTL（对应于An-1和LABA1）和2号染色体上的1个（指定为qAWNL2）。利用具有八种不同纯合基因型组合的植物进一步检查了三个种子遮篷 QTL 之间的基因相互作用。它们的芒长度变异表明这些位点的IR36等位基因在野生稻的遗传背景中具有附加的无芒效应。对于在所有基因座具有IR36纯合等位基因的植物，观察到最短的芒长度，使芒长度减少约75%。通过精细定位，新的 qAWNL2 基因座的候选区域被界定在包含日本晴基因组中 22 个预测基因的 157.4 kb 区域中。结论 QTL分析表明An-1、LABA1和qAWNL2这3个位点是水稻IR36无芒的主要原因。在野生遗传背景下，三个遮阳基因座的功能丧失等位基因对长度减少显示出累加效应。在水稻驯化过程中，无芒形式可能是通过芒位点突变的积累而逐渐产生的。
Background Awns are bristle-like organs at the tips of the glumes. Wild rice has maintained long awns for successful seed propagation through seed dispersal. Seed awning is an interesting trait in rice domestication. Long awns might have been beneficial for seed gatherers in the initial phase of domestication; however, awnless phenotypes were preferably selected in a later phase with non-seed-shattering plants. Investigation of domestication loci associated with awnlessness in cultivated rice will be useful in clarifying the process and history of rice domestication. Results Quantitative trait locus (QTL) analysis for seed awning was carried out using a BC3F2 population between Oryza sativa IR36 (a cultivated donor parent with awnless phenotype) and O. rufipogon W630 (a wild recurrent parent with awns). As a result, two QTLs on chromosome 4 (corresponding to An-1 and LABA1) and one on chromosome 2 (designated as qAWNL2) were detected. Gene interaction among three seed-awning QTLs were further examined with the plants having eight different combinations of homozygous genotypes. Their awn length variation indicated that the IR36 alleles at these loci had the additive awnlessness effects in the genetic background of wild rice. The shortest awn length was observed for the plants having IR36 homozygous alleles at all loci, giving about 75% reduction in awn length. By the fine mapping, the candidate region of the novel qAWNL2 locus was delimited in a 157.4-kb region containing 22 predicted genes in Nipponbare genome. Conclusions QTL analysis revealed that three loci, An-1, LABA1 and qAWNL2, were mainly responsible for the awnlessness of O. sativa IR36. In the wild genetic background, loss-of-function alleles at three awning loci showed additive effects on length reduction. In rice domestication, awnless forms may be gradually generated through the accumulation of mutations at awning loci.