The role of Phytopthora parasitica PpRxLR1 and PpRxLR6 effector proteins in plant immunity
Supplementary data presenting the role of P. parasitica PpRxLR1 and PpRxLR6 in plant immunity. The in silico analyses revealed that P. parasitica INRA 310 secrete 71 conserved RxLR effectors. Among the 71 CRE, PpRxLR1 and PpRxLR6 effector proteins were selected for further functional characterization. Inoculation of Nicotiana benthamiana leaves with zoospores indicated that the life cycle of P. parasitica switches from asymptomatic to symptomatic phase. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) analyses of the inoculated leaves showed that parasitica PpRxLR1 and PpRxLR6 are expressed during the biotrophic phase, suggesting their importance in virulence. Findings from Agrobacterium tumefacient-mediated transient expression of PpRxLR1 and PpRxLR6 in N. benthamiana revealed potential mechanisms of P. parasitica PpRxLR1 and PpRxLR6 in promoting disease development, this includes inducing reactive oxygen species as well as callose deposition. In addition, RT-PCR analyses revealed that PpRxLR1 and PpRxLR6 induce phytohormones (SA, ET, JA) and MAPKs (MPK3 and MPK6). These data indicate that both PpRxLR1 and PpRxLR6 are important virulence factors of P. parasitica.