Tolerance of olive ( Olea europaea ) cv Frantoio to Verticillium dahliae relies on both basal and pathogen‐induced differential transcriptomic responses

Summary Verticillium wilt of olive ( VWO ) is one of the most serious biotic constraints for this tree crop. Our knowledge of the genetics of the tolerance/resistance to this disease is very limited. Here we show that tolerance of the cv Frantoio relies on both basal and early pathogen‐induced differential transcriptomic responses. A comparative transcriptomic analysis ( RNA ‐seq) was conducted in root tissues of cvs Frantoio ( VWO ‐tolerant) and Picual ( VWO ‐susceptible). RNA samples originated from roots of inoculated olive plants during the early infection stages by Verticillium dahliae (highly virulent, defoliating pathotype). A huge number of differentially expressed genes ( DEG s) were found between ‘Frantoio’ and ‘Picual’ (27 312 unigenes) in the absence of the pathogen. Upon infection with V. dahliae , ‘Picual’ and ‘Frantoio’ plants responded differently too. In the early infection stages, four clusters of DEG s could be identified according to their time‐course expression patterns. Among others, a pathogenesis‐related protein of the Bet v I family and a dirigent‐like protein involved in lignification, and several BAK 1 , NHL 1 , reactive oxygen species stress response and BAM unigenes showed noticeable differences between cultivars. Tolerance of ‘Frantoio’ plants to VWO is a consequence of a complex and multifaceted process which involves many plant traits.