華中農(nóng)業(yè)大學學者在甘藍型油菜角果光合作用與種子產(chǎn)量形成機制研究中取得新進展

　　近日，華中農(nóng)業(yè)大學植物營養(yǎng)生物學團隊在The Plant Journal發(fā)表了題為“Trehalose-6-phosphate synthase 8 increases photosynthesis and seed yield in Brassica napus”的學術論文，揭示了甘藍型油菜角果光合作用與種子產(chǎn)量形成中海藻糖-6-磷酸合成酶基因BnaC02.TPS8的功能。

 

　　海藻糖-6-磷酸（T6P）是植物體中蔗糖有效性和碳代謝的關鍵信號分子，它在調(diào)節(jié)蔗糖的利用和分配以及驅(qū)動作物生長和產(chǎn)量形成中起著關鍵作用。T6P合成酶（TPS）可劃分為I類和II類，其中I類TPS是植物中合成T6P的關鍵酶，雖然II類不能直接合成T6P，但它們被認為在海藻糖代謝中起著關鍵的調(diào)節(jié)作用。然而，它們在碳代謝和作物產(chǎn)量中的功能仍然未知。

 

　　該團隊以我國重要油料作物-甘藍型油菜為研究對象，通過構建轉基因材料，探究II類T6P合成酶基因TPS8在碳氮代謝和油菜產(chǎn)量上的功能。結果表明，BnaC02.TPS8主要在甘藍型油菜成熟葉片和發(fā)育中的角果皮中高量表達，亞細胞定位表明其定位于細胞質(zhì)。與野生型相比，BnaC02.TPS8超表達株系光合作用顯著提升，糖、淀粉和生物量的積累顯著增加。此外，BnaC02.TPS8促進光合同化物向淀粉和蔗糖的轉化，同時減少糖酵解中間產(chǎn)物和有機酸的積累，且該過程與TPS活性呈正相關。田間試驗結果表明，無論高氮還是低氮，BnaC02.TPS8均能夠提高甘藍型油菜種子產(chǎn)量，促進種子油脂積累，改善油脂脂肪酸組成。這些結果表明II類TPS對甘藍型油菜光合作用和種子產(chǎn)量的影響起著重要作用，未來育種中BnaC02.TPS8是提高油菜種子產(chǎn)量的理想靶點之一。

 

　　我校博士后袁盼為論文第一作者，石磊教授為論文通訊作者。我校已畢業(yè)碩士生余明珠，博士生周貴龍、劉海疆，團隊蔡紅梅副教授、汪社亮副教授、王創(chuàng)教授、徐芳森教授，洪登峰教授、英國雷丁大學John P. Hammond教授也參與了該項研究。該研究得到了國家自然科學基金和國家留學基金委項目的資助。

 

　　【英文摘要】

 

　　Trehalose-6-phosphate （T6P） functions as a vital proxy for assessing carbohydrate status in plants. While class II T6P synthases （TPS） do not exhibit TPS activity, they are believed to play pivotal regulatory roles in trehalose metabolism. However, their precise functions in carbon metabolism and crop yield have remained largely unknown. Here, BnaC02.TPS8, a class II TPS gene, is shown to be specifically expressed in mature leaves and the developing pod walls of Brassica napus. Over expression of BnaC02.TPS8 increased photosynthesis and the accumulation of sugars, starch, and biomass compared to wild type. metabolomic analysis of BnaC02.TPS8 overexpressing lines and CRISPR/Cas9 mutants indicated that BnaC02.TPS8 enhanced the partitioning of photoassimilate into starch and sucrose, as opposed to glycolytic intermediates and organic acids, which might be associated with TPS activity. Furthermore, the overexpression of BnaC02.TPS8 not only increased seed yield but also enhanced seed oil accumulation and improved the oil fatty acid composition in B. napus under both high nitrogen （N） and low N conditions in the field. These results highlight the role of class II TPS in impacting photosynthesis and seed yield of B. napus, and BnaC02.TPS8 emerges as a promising target for improving B. napus seed yield.