Molecular Detection of the Grapevine Pathogens Plasmopara viticola and Erysiphe necator from Airborne Inoculum Collector Cyclones

Abstract

Grapevine (Vitis vinifera L.) varieties are particularly susceptible to the pathogens downy mildew Plasmopara viticola and powdery mildew Erysiphe necator. Conventional methods for identifying and classifying spores rely on time-consuming microscopic examinations susceptible to human error and requiring qualified personnel. The aim of the present work has focused on the establishment of a protocol for the rapid molecular detection of the fungal species P. viticola and E. necator from adhesive tapes used to trap spores in airborne inoculum collector cyclones. Four DNA extraction methods were tested. Subsequently, molecular detection of both pathogens was performed by validating some of the specific molecular markers available in the literature. PCR with the primers Nad9 cob-F/Nad9 cob-R and Uncin144/Uncin511 showed specific results for P. viticola and E. necator, respectively, and the best results were obtained with the T-CTAB method. The methodology developed in this work could be of great help for relating direct measurement of P. viticola and E. necator airborne inoculum to disease risk and detection of pathogens, which could be integrated into the early diagnosis of these grapevine pathogens, improving existing warning systems such as Decision Support Systems.