Functional Genomics of G-protein coupled receptors (GPCR) in Phytophthora sojae

G protein coupled receptors (GPCRs) present a large family of receptors involved in a broad spectrum of cell signaling, which are responsive for transmitting the extracellular signals to intracellular response by stimuli. Despite exhibiting striking diversity in primary sequence and biology function, all GPCRs possess the conserved fundamental architecture consisting of seven transmembrane domains and share common mechanisms of signal transduction. This class of protein were primarily identified in the gnome of Phytophthora sojae, the destructive cause of stem and root rot in soybean. P. sojae have approximately 41 seven transmembrane proteins, which are classified into five classes based on sequence homology, including metabotropic glutamate receptors, rhodopsin-like superfamily, cyclic AMP receptors, one novel class phosphatidylinositol phosphate kinases with a G-protein coupled receptor, and other unclassified proteins. Subsequently, the expression profiles were evaluated during asexual lifestages, stresses treatments and infection stage. The results showed that some genes were constitutively expressed; in contrast, the other genes are induced during zoosporogenesis or stresses. Finally, genetic transformation of homology-dependent gene silencing of P. sojae were performed and the gene-silenced mutants of five genes were generated respectively. We found that out of five genes, three genes are probably involved in sexual reproduction and pathogenicity, while two genes are not obviously affected the phenotypes including chemotaxis to isofalvone. Further study on these mutants, and other GPCRs genes will be focused on to elucidate the functions of all GPCRs genes in P. sojae growth, development, stress response, chemotaxis and pathogenesis.