Characterization of PHT Genes in 'duli' (Pyrus betulifolia Bunge) and Expression Analysis of PbPHTs in Response to Plant Growth Regulators, P, and Salt Stress

The phosphate transporter (PHT) family plays an important role in the uptake and transport of P elements in plants. A total of 158 PbPHTs were identified from the genome of 'duli' (Pyrus betulifolia Bunge) in this study, including 70 PbPHT1s, 2 PbPHT2s, 70 PbPHT3s, 12 PbPHT4s, and 4 PbPHT5s. Among the 158 PHT genes, 150 were localized to 17 'duli' chromosomes. Gene duplication analysis identified 18 tandemly duplicated gene pairs. The promoter analysis showed that there were a large number of cis-acting elements related to phytohormones, growth, development, stress, and light response in PbPHTs. qRT-PCR analysis revealed that most PHT genes in 'duli' were highly expressed in the fruits, flowers, leaves, stems, and roots, and 15 PbPHT genes were responsive to 5 mu M, 0.5 mM, 5 mM H2PO4, NaCl, GR24 (synthetic SL analog), GA3 (gibberellin 3), ABA (abscisic acid), and IAA (indole-3-acetic acid). GR24, GA3, IAA, and 5 mM KH2PO4 treatments could increase the concentration, absorption, transport, and distribution of P elements in the rhizomes and leaves of 'duli', but 5 mu M KH2PO4, NaCl, and ABA had the opposite effect. This study therefore provides a list of PbPHT genes with substantial roles in abiotic stress response, as well as important information to understand the functional characteristics of PbPHT during 'duli' abiotic stress tolerance, and explores the function of PbPHTs in exogenous hormones, phosphorus, and salt stress in the future.