Genome-wide identification and expression analysis of phosphate-sensing SPX proteins in oats

Phosphorus is indispensable to plant growth and development. Soil phosphorus deficiency poses a substantial constraint on crop yield. SPXs play pivotal roles in phosphate transport and absorption in plants. Yet, the functions of SPXs of oat <i>(Avena sativa</i> L.) under abiotic stresses remain unclear. In this study, we conducted a genome-wide analysis of 169 <i>SPXs</i> from hexaploid oat and five closely related plant species. All homologous <i>AsSPXs</i> were found to arise from duplication events and depict a strong purifying selection. Subcellular localization prediction revealed that AsSPXs were mainly located on the plasma membrane. Seventeen <i>cis</i>-acting elements, predominantly comprising light-, low temperature-, abscisic acid-, and drought-responsive elements, were dispersed in the promoter regions of <i>AsSPXs</i>. Analysis of <i>cis</i>-regulatory elements, protein-protein interaction networks, and qRT-PCR showed that <i>AsSPXs</i> are not solely involved in phosphorus starvation response but also in various stress responses. Notably, <i>AsSPX18-5D</i> (<i>AVESA.00001b.r3.5Dg0002895</i>) exerted pivotal roles in conferring resistance against low phosphorus, salt, and ABA treatments. Our study aimed to explore important stress-resistant genes in oat. Our results could provide a basis for future studies on the evolution and functions of the <i>AsSPX</i> gene family and a crucial foundation for comprehending how oat responds to environmental stresses.