BnPHT5;1b的突变导致油菜在正常磷和高磷条件下生长迟缓

甘蓝型油菜PHT5家族8个成员中只有BnaA09PHT5;1b和BnCnPHT5;1b受供磷诱导。两个基因均在液泡膜上定位，具有磷转运活性。利用Crispr-Cas9技术构建BnPHT5;1bs双突变体材料，结果表明BnPHT5;1bs双突变体苗期根细胞液泡中无机磷浓度显著下降，磷含量降低，但根冠比增加导致苗期地上部叶片无机磷浓度始终高于野生型，这与模式植物拟南芥中的研究结果存在差异（拟南芥vpt1突变体地上部叶片无机磷浓度低于野生型）。在油菜花期，BnPHT5;1bs双突变体中磷被过度分配到花器官中，从而导致后期种子发育出现异常，种子性状明显受到影响，说明BnPHT5;1bs影响了油菜整个植株的磷稳态。而将BnPHT5;1bs两个基因在拟南芥野生型中超表达，转基因植株出现了较好的长势，这为提高油菜磷高效利用效率提供了一种新的思路。

韩贝博士为论为第一作者，汪社亮副教授和石磊教授为共同通讯作者。课题组王创教授、丁广大教授、徐芳森教授、蔡红梅副教授、英国詹姆斯·赫顿研究所Philip J. White教授、博士后严军军，博士生吴涛、硕士生姜澳生也参与了该项研究。浙江大学刘于老师和中科院物数所董旭研究员提供了核磁共振技术支撑。该研究得到了国家自然科学基金和国家重点研发计划重点项目的资助。

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通讯员：姜澳生

审核人：汪社亮

【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.

原文链接：https://onlinelibrary.wiley.com/doi/10.1111/pce.14423