華中農(nóng)業(yè)大學油菜團隊揭示油菜葉片衰老過程中磷脂代謝介導(dǎo)的磷素回收利用機制

 

　　近日， Genome Biology以“Phospholipase-mediated phosphate recycling during plant leaf senescence”為題在線發(fā)表了我校油菜團隊最新研究成果。該研究中發(fā)現(xiàn)油菜等植物葉片衰老過程中由磷脂酶介導(dǎo)的膜磷脂水解是植物細胞磷回收的關(guān)鍵途徑之一。衰老誘導(dǎo)表達的非特異性磷脂酶C4 （Nonspecific phospholipase C4， NPC4）和磷脂酶Dζ2 （phospholipase Dζ2，PLDζ2）是介導(dǎo)這一代謝過程的關(guān)鍵磷脂酶。

 

　　葉片衰老過程中，超過90%的磷會從衰老的葉片中回收。油菜葉片衰老過程中磷脂酶PLD和PLC活性被高度誘導(dǎo)。分析油菜葉片發(fā)育時間序列轉(zhuǎn)錄組，發(fā)現(xiàn)葉片衰老相關(guān)基因與植物缺磷響應(yīng)和脂質(zhì)代謝相關(guān)基因高度共表達。進一步分析植物磷脂代謝相關(guān)基因表達譜，發(fā)現(xiàn)油菜葉片衰老過程中磷脂酶基因NPC4和PLDζ2被顯著誘導(dǎo)表達，同時油菜發(fā)育各組織各時期表達譜中這兩類磷脂酶基因主要在衰老組織中高表達，它們的表達模式與植物葉片衰老、響應(yīng)ABA、響應(yīng)缺磷脅迫和脂質(zhì)代謝相關(guān)基因高度相似。

 

　　進一步通過基因功能驗證，發(fā)現(xiàn)NPC4和PLDζ2在油菜葉片衰老過程中發(fā)揮著關(guān)鍵作用。NPC4和PLDζ2的敲除突變體會延緩膜磷脂的降解，并延遲油菜葉片的衰老。相反，NPC4和PLDζ2過表達會加速膜磷脂的降解和葉片衰老，促進脂質(zhì)磷從衰老葉片中再回收到幼嫩組織中，進而提高磷素利用效率促進植物的生長。同事，大豆、玉米、棉花等10種植物衰老葉片中磷和磷脂含量、磷脂酶基因表達分析結(jié)果表明，葉片衰老過程中由膜磷脂水解介導(dǎo)的磷回收過程在植物中是保守的。該研究指出NPC4和PLDζ2介導(dǎo)的膜磷脂水解促進了脂質(zhì)磷從衰老葉片到幼嫩葉片中的再利用，并且磷脂水解介導(dǎo)的磷素回收利用提高了作物的磷素利用效率。

 

　　華中農(nóng)業(yè)大學、美國密蘇里大學圣路易斯分校、唐納德丹佛斯植物科學中心博士后楊報為本文的第一作者，崖州灣國家實驗室博士后譚增棟對轉(zhuǎn)錄組和脂質(zhì)組數(shù)據(jù)進行了分析，美國密蘇里大學圣路易斯分校、唐納德丹佛斯植物科學中心王學敏教授對論文修改提供了寶貴意見，我校郭亮教授和魯少平副研究員為共同通訊作者。

 

　　【英文摘要】

 

　　Background

 

　　Phosphorus is a macronutrient necessary for plant growth and development and its availability and efficient use affect crop yields. Leaves are the largest tissue that uses phosphorus in plants, and membrane phospholipids are the main source of cellular phosphorus usage.

 

　　Results

 

　　Here we identify a key process for plant cellular phosphorus recycling mediated by membrane phospholipid hydrolysis during leaf senescence. Our results indicate that over 90% of lipid phosphorus, accounting for more than one-third of total cellular phosphorus, is recycled from senescent leaves before falling off the plants. Nonspecific phospholipase C4 （NPC4） and phospholipase Dζ2 （PLDζ2） are highly induced during leaf senescence, and knockouts of PLDζ2 and NPC4 decrease the loss of membrane phospholipids and delay leaf senescence. Conversely, overexpression of PLDζ2 and NPC4 accelerates the loss of phospholipids and leaf senescence, promoting phosphorus remobilization from senescent leaves to young tissues and plant growth. We also show that this phosphorus recycling process in senescent leaves mediated by membrane phospholipid hydrolysis is conserved in plants.

 

　　Conclusions

 

　　These results indicate that PLDζ2- and NPC4-mediated membrane phospholipid hydrolysis promotes phosphorus remobilization from senescent leaves to growing tissues and that the phospholipid hydrolysis-mediated phosphorus recycling improves phosphorus use efficiency in plants.

 

　　論文鏈接：https://genomebiology.biomedcentral.com/articles/10.1186/s13059-024-03348-x