Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Biologibygget, Framstredet 39, 9037, Tromsø, Norway.
Planta. 2019 Jul;250(1):245-261. doi: 10.1007/s00425-019-03161-y. Epub 2019 Apr 16.
The plastid phosphate translocators evolved in algae but diversified into several groups, which adopted different physiological functions by extensive gene duplications and losses in Streptophyta. The plastid phosphate translocators (pPT) are a family of transporters involved in the exchange of metabolites and inorganic phosphate between stroma and cytosol. Based on their substrate specificities, they were divided into four subfamilies named TPT, PPT, GPT and XPT. To analyse the occurrence of these transporters in different algae and land plant species, we identified 652 pPT genes in 101 sequenced genomes for phylogenetic analysis. The first three subfamilies are found in all species and evolved before the split of red and green algae while the XPTs were derived from the duplication of a GPT gene at the base of Streptophyta. The analysis of the intron-exon structures of the pPTs corroborated these findings. While the number and positions of introns are conserved within each subfamily, they differ between the subfamilies suggesting an insertion of the introns shortly after the three subfamilies evolved. During angiosperm evolution, the subfamilies further split into different groups (TPT1-2, PPT1-3, GPT1-6). Angiosperm species differ significantly in the total number of pPTs, with many species having only a few, while several plants, especially crops, have a higher number, pointing to the importance of these transporters for improved source-sink strength and yield. The differences in the number of pPTs can be explained by several small-scale gene duplications and losses in plant families or single species, but also by whole genome duplications, for example, in grasses. This work could be the basis for a comprehensive analysis of the molecular and physiological functions of this important family of transporters.
质体磷酸转运蛋白在藻类中进化，但在石松类植物中通过广泛的基因复制和丢失而多样化为几个组，采用了不同的生理功能。质体磷酸转运蛋白（pPT）是一组参与代谢物和无机磷酸盐在基质和胞质溶胶之间交换的转运体。根据它们的底物特异性，它们被分为四个亚家族，分别命名为 TPT、PPT、GPT 和 XPT。为了分析这些转运体在不同藻类和陆地植物物种中的存在情况，我们在 101 个测序基因组中鉴定了 652 个 pPT 基因进行系统发育分析。前三个亚家族存在于所有物种中，在红藻和绿藻分裂之前进化，而 XPT 则是在石松类植物基部的 GPT 基因复制的结果。pPT 基因的内含子-外显子结构分析证实了这些发现。虽然每个亚家族内的内含子数量和位置是保守的，但它们在亚家族之间存在差异，这表明内含子是在三个亚家族进化后不久插入的。在被子植物进化过程中，亚家族进一步分裂为不同的组（TPT1-2、PPT1-3、GPT1-6）。被子植物物种在 pPT 总数上差异显著，许多物种只有少数几个，而一些植物，特别是作物，具有更高的数量，这表明这些转运体对于提高源库强度和产量非常重要。pPT 数量的差异可以用植物科或单个物种中的几个小规模基因复制和丢失来解释，但也可以用全基因组复制来解释，例如在禾本科中。这项工作可以为这个重要的转运体家族的分子和生理功能的综合分析奠定基础。
