Function of LRR domain in grape MrRPV1

ObjectiveThe function of LRR domain of grape downy mildew resistance protein(MrRPV1) in downy mildew pathogen specific recognition was investigated in order to provide basis for studying the interaction mechanism between grape and downy mildew pathogen. MethodThe LRR domains of MrRPV1 and powdery mildew resistance protein (Mr-RUN1) were switched and recombinant expression plasmids were constructed in this study. The recombinant expression plasmids were transformed into embryonic callus of Shiraz grape which was susceptible to downy mildew and powdery mildew so as to obtain transgenic plants. Disease resistance of the transgenic plants was identified by DNA and RNA molecular level detection and indoor inoculation test. ResultIn total, seven RGA10-8LRR(recombination of LRR domains of Mr-RPV1 ) and six RGA8-10LRR ( recombination of LRR domains of MrRUN1 ) positive transgenic lines were obtained . Among the seven RGA10-8LRR transgenic lines, only RGA10-8-13 line exhibited similar necrotic spots to MrRPV1 transgenic plant S8-1 with no visible downy mildew. Furthermore, all the seven RGA10-8LRR transgenic lines showed no significant powdery mildew resistance. Powdery mildew resistance was observed in two RGA8-10LRR transgenic lines , namely RGA8-10-3 and RGA8-10-28, with programmed cell necrosis(PCD) in 35% cells. All the six RGA8-10LRR transgenic lines showed no downy mildew resistance. ConclusionLRR domain of MrRPV1 may play a role in specific recognition of grape downy mildew pathogen and LRR domain of MrRUN1 may play a role in specific recognition of pow-dery mildew pathogen.