Beijing Key Laboratory for Agricultural Application and New Technique, College of Plant Science and Technology, Beijing University of Agriculture, Beijing, 102206, China.
Bei Jing Bei Nong Enterprise Management Co., Ltd., Beijing, 102206, China.
Plant Cell Environ. 2019 Sep;42(9):2715-2729. doi: 10.1111/pce.13598. Epub 2019 Jul 31.
Phosphorus (P) is essential for plant growth and development, and the vacuole is an important organelle for phosphate storage. However, the tonoplast phosphate transporter in fleshy fruits remains unknown. In this study, based on the strawberry (Fragaria × ananassa) fruit transcriptome data, a tonoplast-localized vacuolar phosphate transporter with SPX and major facilitator superfamily domains, FaVPT1, was identified. FaVPT1 expression was highest in the fruits and could be induced by sucrose. Using transient transgenic systems in strawberry fruit, the downregulation and upregulation of FaVPT1 inhibited and promoted ripening, respectively, and affected phosphate contents, fruit firmness, sugar and anthocyanin contents, and ripening-related gene transcription. FaVPT1 could rescue Pi absorption in both yeast and the Arabidopsis atvpt1 mutant, confirming the similar function of FaVPT1 and AtVPT1, a previously identified tonoplast phosphate transporter in Arabidopsis. The Escherichia coli-expressed SPX domain of FaVPT1 could strongly bind to InsP with a K of 3.5 μM. The results demonstrate that FaVPT1 is a tonoplast phosphate transporter and regulates strawberry fruit ripening and quality, to a large extent, via sucrose.
磷（P）是植物生长和发育所必需的，液泡是磷酸盐储存的重要细胞器。然而，肉质果实中的液泡膜磷酸盐转运体仍然未知。在这项研究中，基于草莓（ Fragaria ×ananassa ）果实转录组数据，鉴定了一种具有 SPX 和主要易化剂超家族结构域的液泡膜定位的液泡磷酸盐转运体 FaVPT1。FaVPT1 在果实中的表达水平最高，可被蔗糖诱导。通过在草莓果实中瞬时转化系统，下调和上调 FaVPT1 分别抑制和促进了成熟，并影响了磷酸盐含量、果实硬度、糖和花青素含量以及成熟相关基因的转录。FaVPT1 可以在酵母和拟南芥 atvpt1 突变体中挽救 Pi 吸收，证实了 FaVPT1 和 AtVPT1 的相似功能，AtVPT1 是先前在拟南芥中鉴定的液泡膜磷酸盐转运体。大肠杆菌表达的 FaVPT1 的 SPX 结构域可以与 InsP 强烈结合，Kd 值为 3.5 μM。结果表明，FaVPT1 是一种液泡膜磷酸盐转运体，通过蔗糖在很大程度上调节草莓果实的成熟和品质。
