近日，華中農(nóng)業(yè)大學(xué)資源與環(huán)境學(xué)院植物營(yíng)養(yǎng)生物學(xué)團(tuán)隊(duì)研究成果“The transcription factor BnaA9.WRKY47 coordinates leaf senescence and nitrogen remobilization in Brassica napus”在植物學(xué)雜志Journal of Experimental Botany上發(fā)表。

 

　　甘藍(lán)型油菜根系吸收的總氮中，大約48%從營(yíng)養(yǎng)組織回收到成熟的種子中，另外大約15%的氮因落葉而損失。因此，改善衰老葉片中的氮素回收，提高氮素再利用效率十分重要。研究發(fā)現(xiàn)，BnaA9.WRKY47超表達(dá)植株表現(xiàn)出葉片提前衰老，葉綠體降解的表型。BnaA9.WRKY47超表達(dá)株系的籽粒產(chǎn)量較野生型顯著提高；相反，BnaA9.WRKY47功能缺失突變體的產(chǎn)量降低。

 

　　通過(guò)生化實(shí)驗(yàn)分析，研究團(tuán)隊(duì)發(fā)現(xiàn)BnaA9.WRKY47直接激活持綠基因BnaC7.SGR1以加速老葉黃化衰老。研究表明伴隨著缺氮誘導(dǎo)的葉片衰老，超表達(dá)株系老葉中氨基酸濃度升高，氮素再分配能力提高。同時(shí)BnaA9.WRKY47能夠協(xié)同激活氨基酸滲透酶BnaA9.AAP1和硝酸鹽轉(zhuǎn)運(yùn)蛋白BnaA2.NTR1.7。因此，研究團(tuán)隊(duì)提出缺氮脅迫下油菜提高氮素再利用理論模型：缺氮上調(diào)老葉BnaA9.WRKY47基因的表達(dá)，增加老葉中BnaA9.WRKY47蛋白豐度，BnaA9.WRKY47上調(diào)了BnaC7.SGR1、BnaA2.NRT1.7和BnaA9.AAP1的表達(dá)，從而促進(jìn)了甘藍(lán)型油菜老葉的衰老以及氮素向新生組織或種子的再轉(zhuǎn)運(yùn)，有利于缺氮脅迫下油菜達(dá)到養(yǎng)分資源配置最大化。

 

　　華中農(nóng)業(yè)大學(xué)植物營(yíng)養(yǎng)生物學(xué)團(tuán)隊(duì)博士研究生崔蕊為論文第一作者，徐芳森教授和汪社亮副教授為共同通訊作者，我校石磊教授、已畢業(yè)博士馮英娜和碩士研究生姚金亮也參與了該項(xiàng)研究。該研究得到了國(guó)家重點(diǎn)研發(fā)計(jì)劃和國(guó)家自然科學(xué)基金的支持。

 

　　論文鏈接：https://academic.oup.com/jxb/advance-article/doi/10.1093/jxb/erad282/7227263

 

　　英文摘要：

 

　　Nitrogen （N） is an essential macronutrient for plants, and N remobilization is key for plant adaptation to N deficiency stress. However, there is a limited understanding of the regulatory mechanisms of N remobilization in Brassica napus. Here, we report a transcription factor, BnaA9.WRKY47, induced by N starvation. At the seedling stage, BnaA9.WRKY47-OE lines displayed earlier senescence of older leaves and preferential growth of juvenile leaves compared to the wild-type 'Westar 10' under N starvation. At the field scale, the seed yield was significantly increased in BnaA9.WRKY47-OE lines compared to 'Westar 10' grown under N deficiency conditions and, conversely, reduced in BnaA9.WRKY47-mutants. Biochemical analyses demonstrate that BnaA9.WRKY47 directly activates BnaC7.SGR1 to accelerate older leaf senescence. In line with leaf senescence, the amino acid concentration was elevated, and the N distribution was reduced in the older leaves of OE lines. This result is because BnaA9.WRKY47 activates the amino acid permease BnaA9.AAP1 and the nitrate transporter BnaA2.NRT1.7. Therefore, the expression of BnaA9.WRKY47 efficiently facilitates N remobilization from older to younger leaves or seeds. Taken together, the results of this study demonstrate that BnaA9.WRKY47 upregulates the expression of BnaC7.SGR1, BnaA2.NRT1.7 and BnaA9AAP1 thus promoting the remobilization of N in B. napus under N starvation.