Department of Agronomy, College of Agriculture and Life Sciences, Chungnam National University, Daejeon 34134, Republic of Korea.
Department of Southern Area Crop Science, Rural Development Administration, Miryang 50424, Republic of Korea.
J Exp Bot. 2021 May 28;72(12):4254-4268. doi: 10.1093/jxb/erab155.
We previously identified a cluster of yield-related quantitative trait loci (QTLs) including plant height in CR4379, a near-isogenic line from a cross between Oryza sativa spp. japonica cultivar 'Hwaseong' and the wild relative Oryza rufipogon. Map-based cloning and transgenic approaches revealed that APX9, which encodes an l-ascorbate peroxidase 4, is associated with this cluster. A 3 bp InDel was observed leading to the addition of a valine in Hwaseong compared with O. rufipogon. APX9-overexpressing transgenic plants in the Hwaseong background were taller than Hwaseong. Consistent with these results, APX9 T-DNA insertion mutants in the japonica cultivar Dongjin were shorter. These results confirm that APX9 is the causal gene for the QTL cluster. Sequence analysis of APX9 from 303 rice accessions revealed that the 3 bp InDel clearly differentiates japonica (APX9HS) and O. rufipogon (APX9OR) alleles. indica accessions shared both alleles, suggesting that APX9HS was introgressed into indica followed by crossing. The finding that O. rufipogon accessions with different origins carry APX9OR suggests that the 3 bp insertion was specifically selected in japonica during its domestication. Our findings demonstrate that APX9 acts as a major regulator of plant development by controlling a valuable suite of agronomically important traits in rice.
我们之前在 CR4379 中鉴定出了一个与产量相关的数量性状位点 (QTL) 簇，该品系是由粳稻品种 'Hwaseong' 和野生近缘种 Oryza rufipogon 杂交得到的近等基因系。基于图谱的克隆和转基因方法表明，APX9 编码 l-抗坏血酸过氧化物酶 4，与该簇有关。与 O. rufipogon 相比，在 Hwaseong 中观察到 3 bp 的 InDel，导致添加了一个缬氨酸。在 Hwaseong 背景下过表达 APX9 的转基因植株比 Hwaseong 更高。与这些结果一致，在粳稻品种 Dongjin 中的 APX9 T-DNA 插入突变体更矮。这些结果证实 APX9 是该 QTL 簇的候选基因。对来自 303 个水稻品种的 APX9 进行序列分析表明，3 bp 的 InDel 清楚地区分了粳稻（APX9HS）和 O. rufipogon（APX9OR）等位基因。籼稻品种同时携带这两个等位基因，表明 APX9HS 是在籼稻引入后通过杂交传入的。发现来自不同起源的 O. rufipogon 品种携带 APX9OR 表明，在粳稻驯化过程中，3 bp 的插入被特异性选择。我们的研究结果表明，APX9 通过控制一系列重要的农艺性状，作为植物发育的主要调节剂在水稻中起作用。
