A dual Resistance-gene system confers resistance against fungal and bacterial pathogens in transgenic Brassica rapa.

Abstract

Colletotrichum higginsianum is a fungal pathogen that infects a wide variety of cruciferous plants causing important crop losses. By map-based cloning and natural variation analyses, we found that both RRS1 and RPS4 genes are required for resistance to C. higginsianum, Ralstonia solanacearum and Pseudomonas syringae pv. tomato strain DC3000 expressing avrRps4. Furthermore, we transformed both RPS4-Ws and RRS1-Ws into Brassica rapa cv. Osome (Komatsuna) and subsequently obtained 25 transformants that contain either one or two R-genes. T2 transformants containing both RPS4-Ws and RRS1-Ws showed resistance to C. higginsianum and R. solanacearum. On the contrary, T2 transformants containing either RPS4-Ws or RRS1-Ws showed susceptible to their pathogens. These results suggest that a dual resistance gene system also functions in B. rapa as well as Arabidopsis thaliana. To test whether a dual resistance gene system functions in various plant species, we have transformed them into the solanaceous plants Nicotiana benthamiana and tomato (Solanum lycopersicum).