Identification and expression analysis of Phosphate Transporter 1 (PHT1) genes in the highly phosphorus‐use‐efficient Hakea prostrata (Proteaceae)

Abstract

Heavy and costly use of phosphorus (P) fertiliser is often needed to achieve high crop yields, but only a small amount of applied P fertiliser is available to most crop plants. Hakea prostrata (Proteaceae) is endemic to the P‐impoverished landscape of southwest Australia and has several P‐saving traits. We identified 16 members of the Phosphate Transporter 1 (PHT1) gene family (HpPHT1;1‐HpPHT1;12d) in a long‐read genome assembly of H. prostrata. Based on phylogenetics, sequence structure and expression patterns, we classified HpPHT1;1 as potentially involved in Pi uptake from soil and HpPHT1;8 and HpPHT1;9 as potentially involved in Pi uptake and root‐to‐shoot translocation. Three genes, HpPHT1;4, HpPHT1;6 and HpPHT1;8, lacked regulatory PHR1‐binding sites (P1BS) in the promoter regions. Available expression data for HpPHT1;6 and HpPHT1;8 indicated they are not responsive to changes in P supply, potentially contributing to the high P sensitivity of H. prostrata. We also discovered a Proteaceae‐specific clade of closely‐spaced PHT1 genes that lacked conserved genetic architecture among genera, indicating an evolutionary hot spot within the genome. Overall, the genome assembly of H. prostrata provides a much‐needed foundation for understanding the genetic mechanisms of novel adaptations to low P soils in southwest Australian plants.