8月20日，華中農(nóng)業(yè)大學(xué)植物營(yíng)養(yǎng)生物學(xué)團(tuán)隊(duì)在Plant, Cell & Environment 上發(fā)表了題為“Identification of vacuolar phosphate influx transporters in Brassica napus”的研究論文，該論文首次從異源四倍體作物甘藍(lán)型油菜PHT5家族八個(gè)成員中鑒定出了兩個(gè)液泡磷儲(chǔ)存轉(zhuǎn)運(yùn)子BnaA09PHT5;1b和BnCnPHT5;1b，揭示了其調(diào)控油菜苗期和生殖生長(zhǎng)期磷穩(wěn)態(tài)的生物學(xué)功能。
磷是植物生長(zhǎng)發(fā)育所必需的營(yíng)養(yǎng)元素之一。在自然界中，植物對(duì)生長(zhǎng)介質(zhì)磷濃度的變化主要依靠植物細(xì)胞液泡的緩沖機(jī)制。甘藍(lán)型油菜是我國(guó)也是世界上重要的油料作物，需磷較高且對(duì)磷敏感。甘藍(lán)型油菜是異源四倍體作物，基因組非常復(fù)雜，鑒定其液泡磷轉(zhuǎn)運(yùn)子，研究其在磷穩(wěn)態(tài)中的功能，對(duì)磷高效油菜品種的培育具有重要的生產(chǎn)實(shí)踐意義。
甘藍(lán)型油菜PHT5家族8個(gè)成員中只有BnaA09PHT5;1b和BnCnPHT5;1b受供磷誘導(dǎo)。兩個(gè)基因均在液泡膜上定位，具有磷轉(zhuǎn)運(yùn)活性。利用Crispr-Cas9技術(shù)構(gòu)建BnPHT5;1bs雙突變體材料，結(jié)果表明BnPHT5;1bs雙突變體苗期根細(xì)胞液泡中無(wú)機(jī)磷濃度顯著下降，磷含量降低，但根冠比增加導(dǎo)致苗期地上部葉片無(wú)機(jī)磷濃度始終高于野生型，這與模式植物擬南芥中的研究結(jié)果存在差異（擬南芥vpt1突變體地上部葉片無(wú)機(jī)磷濃度低于野生型）。在油菜花期，BnPHT5;1bs雙突變體中磷被過(guò)度分配到花器官中，從而導(dǎo)致后期種子發(fā)育出現(xiàn)異常，種子性狀明顯受到影響，說(shuō)明BnPHT5;1bs影響了油菜整個(gè)植株的磷穩(wěn)態(tài)。而將BnPHT5;1bs兩個(gè)基因在擬南芥野生型中超表達(dá)，轉(zhuǎn)基因植株出現(xiàn)了較好的長(zhǎng)勢(shì)，這為提高油菜磷高效利用效率提供了一種新的思路。
韓貝博士為論為第一作者，汪社亮副教授和石磊教授為共同通訊作者。課題組王創(chuàng)教授、丁廣大教授、徐芳森教授、蔡紅梅副教授、英國(guó)詹姆斯·赫頓研究所Philip J. White教授、博士后嚴(yán)軍軍，博士生吳濤、碩士生姜澳生也參與了該項(xiàng)研究。浙江大學(xué)劉于老師和中科院物數(shù)所董旭研究員提供了核磁共振技術(shù)支撐。該研究得到了國(guó)家自然科學(xué)基金和國(guó)家重點(diǎn)研發(fā)計(jì)劃重點(diǎn)項(xiàng)目的資助。
【英文摘要】
Recent progress has shown that vacuolar Pi transporters （VPTs） are important for cellular Pi homeostasis in Arabidopsis thaliana and Oryza sativa under fluctuating external Pi supply, but the identity and involvement of VPTs in cellular Pi homeostasis in Brassica napus is poorly understood. Here, we identified two vacuolar Pi influx transporters B. napus, BnA09PHT5;1b and BnCnPHT5;1b, and uncovered their necessity for cellular Pi homeostasis through functional analysis. Both Brassica proteins are homologs of Arabidopsis AtPHT5;1 with a similar sequence, structure, tonoplast localization, and VPT activity. Brassica pht5;1b double mutants had smaller shoots and larger shoot cellular Pi concentrations than wild-type B. napus, which contrasts with a previous study of the Arabidopsis pht5;1 mutant, suggesting that PHT5;1-VPTs play different roles in cellular Pi homeostasis in seedlings of B.napus and A. thaliana. Disruption of BnPHT5;1b genes also caused Pi toxicity in floral organs, reduced seed yield and impacted seed traits, consistent with the proposed role of AtPHT5;1 in floral Pi homeostasis in Arabidopsis. Taken together, our studies identified two vacuolar Pi influx transporters in B. napus and revealed the distinct and conserved roles of BnPHT5;1bs in cellular Pi homeostasis in this plant species.
原文鏈接：https://onlinelibrary.wiley.com/doi/10.1111/pce.14423
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