Abstract:

R3a and RB confer resistance to potato late blight by recognizing the effector protein Avr3a and Avrblb1 of Phytophthora infestans. R gene mediated resistance requires multiple signal transduction pathways. Virus-induced gene silencing (VIGS) is a powerful tool for studying genes participation in signal pathways. Eight genes, SIPK, NDR1, SGT1, HSP90, NPR1, Rar1, EDS1 and WRKY1 from other species are known to be involved in defence-related signal pathway. Expression of each gene was suppressed by VIGS in Nicotiana benthamiana and the effect was determined on Hypersensitive Response symptoms induced by RB-Avrblb1 and R3a-Avr3a. R3a- and RB-mediated resistance was compromised by the silencing of HSP90 and SGT1, suggesting that the RB-Avrblb1 and R3a-Avr3a interaction are dependent on ubiquitin ligase-associated protein SGT1 and heat-shock protein HSP90. The establishment of this system will identify new genes involved in resistance to late blight.

Key words: Late blight, Nicotiana benthamiana, virus induced gene silencing, transient gene expression