Functional Analysis Of RasGTPase PsARF1in Phytophthora Sojae

Soybean is one of the world’s most important crops, Phytophthora sojae can cause damping off and root rot of soybeans, leading to huge economic losses to the world’s soybean industry. Phytophthora sojae belongs to Chromalveolata, P. sojae has been developed as a model species for the Phytophthora spp. The asexual life of P. sojae plays an important role in the disease spread in the field. With the completion of the P. sojae genome sequencing, researchers can analysis gene expression at the molecular levels, it will provide new research methods to find new fungicide target and improve people’s understanding of the molecular pathogenesis of P. sojae.During the infection of plants, P. sojae will deliver kinds of extracellular effectors into the plant cells to disturb resistance of the plants, while plants will recognize these effectors by its resistance gene, so it is very important to identify how effectors are transported and secreted. The vesicles transportation is a basic transportation within the cells, first it’ll budding at a particular area of the membrane and then target the vesicle to the special organelles. The vesicles will travel along the microtubules and microfilament until reach the target. At this place it will fusion with the target membrane with the help of SNAREs and Rab. There are at least three different vesicle coats in cells:coat protein complex I (COPI), COPII and clathrin. COPI-coated vesicles are involved in retrograde transport within the Golgi apparatus and transport from the Golgi to the ER. ARF1is a member of Ras family, it is necessary to the formation of COPI-coated vesicles, and is also an important regulator of transportation.In this study, we obatained one ARF1protein encoding gene in the genome of P. sojae. By investigating its transcription level in different stages we considered that ARFl may plays an important role during the infection. We silenced PsARF1in P6497(race2) by stable transformation of Phytophthora sojae, and obainted three silenced-transformants. Silencing of PsARF1results in three defects of phenotypes:1) growth rate is decreased,2) pathogenicity is significantly reduced,3) secretion of intracellular enzymes is significantly affected. While silenced mutants and the wild type exhibited no difference in the structure of the cell wall. All come to one conclusion that PsARF1is involved in the growth and pathogenicity in P. sojae.