G protein alpha subunit may help zoospore to find the infection site and influence the expression of RGS protein.

Sensing chemical signal secreted from host root and find the best site for penetration are crucial for initiating infection of Phytophthora zoospore. G protein alpha subunit of P. sojae participates in not only the chemotaxis to soybean isoflavone, but also finding penetrating site. Furthermore, although calcium signal pathways are influenced by Galpha, other signal pathways also influenced by G protein remain to be discovered. In this addendum, we describe an RGS protein, PsRGS6, is expressed downregulated in zoospores of Galpha silenced mutant. This result indicates that the expression of Galpha and RGS protein may be influenced by each other. Some differences between Galpha mutants of P. infestans and P. sojae may be due to the different developmental procedures.