Super hybrid rice varieties with ideal plant architecture (IPA) have been critical in enhancing food security worldwide. However, the molecular mechanisms underlying their improved yield remain unclear. Here, we report the identification of a QTL, qWS8/ipa1-2D, in the super rice Yongyou12 (YY12) and related varieties. In-depth genetic molecular characterization of qWS8/ipa1-2D reveals that this newly identified QTL results from three distal naturally occurring tandem repeats upstream of IPA1, a key gene/locus previously shown to shape rice ideal plant architecture and greatly enhance grain yield. The qWS8/ipa1-2D locus is associated with reduced DNA methylation and a more open chromatin state at the IPA1 promoter, thus alleviating the epigenetic repression of IPA1 mediated by nearby heterochromatin. Our findings reveal that IPA traits can be fine-tuned by manipulating IPA1 expression and that an optimal IPA1 expression/dose may lead to an ideal yield, demonstrating a practical approach to efficiently design elite super rice varieties.
具有理想株型的超級(jí)雜交稻品種對(duì)于增加全球糧食安全至關(guān)重要。但是，它們產(chǎn)量提高的潛在分子機(jī)制仍不清楚。本文，我們報(bào)道對(duì)超級(jí)稻甬優(yōu)12和相關(guān)品種中一個(gè)QTL的鑒定，命名為qWS8/ipa1-2D。對(duì)qWS8/ipa1-2D深入的遺傳分子分析表明，這個(gè)新鑒定的QTL來(lái)源于IPA1上游末端的3個(gè)自然發(fā)生的串聯(lián)重復(fù)序列，IPA1是一個(gè)之前鑒定關(guān)鍵基因/位點(diǎn)，影響水稻理想株型形成并極大增強(qiáng)谷物產(chǎn)量。qWS8/ipa1-2D位點(diǎn)與DNA甲基化減弱相關(guān)，IPA1啟動(dòng)子具有更開(kāi)放的染色體狀態(tài)，因而通過(guò)附近的異染色質(zhì)減輕對(duì)IPA1的表觀遺傳抑制。我們的結(jié)果揭示了通過(guò)調(diào)控IPA1的表達(dá)控制IPA性狀，最佳的IPA1表達(dá)/劑量能夠產(chǎn)生高產(chǎn)水稻，證明了有效設(shè)計(jì)超級(jí)稻品種的實(shí)際方法。