Computational Predictions and Evolutionary Analysis of LrK10 Kinase-Related Putative PSTOL1 Gene Homeologs in Wheat and Orthologs of Its Wild Relatives

Phosphorus Starvation Tolerance 1 in rice (OsPSTOL1, known as Phosphorus uptake 1, Pup1) is a receptor-like cytoplasmic protein kinase that confers tolerance to phosphorus deficiency. The OsPSTOL1 gene possesses a Ser/Thr kinase and shows high amino-acid sequence similarity with the leaf rust receptor-like kinase (OsLrK10). We hypothesise that the putative wheat genes TaPSTOL1 and TaLrK10 have a common ancestral origin and that putative TaPSTOL1 diverged recently, acquiring new structural modifications and biological functions in the process. In this study, we identified all putative TaPSTOL1 homeologs and examined the evolutionary relationship between TaPSTOL1 and TaLrK10 in Triticum species. Our results indicate that the putative TaPSTOL1 diverged recently without possessing the amino-terminal domain, which is a typical characteristic of TaLrK10. We observed numerous conversion tracts between these two genes, and the substitution pattern of randomly selected amino acids indicates that dynamic selection pressures acted on both genes. The putative TaPSTOL1 shows high nucleotide diversity compared to TaLrK10 within Triticum species. Further, a multiple-sequence analysis reveals that the third exon of TaLrK10 appears to have been duplicated and diverged as a putative single-exon-based TaPSTOL1 in bread wheat. Overall, our comparative analysis indicates that both TaPSTOL1 and TaLrK10 appear to have diverged from a common ancestor, acquiring distinct structural organisations and biological functions.