Quercus robur isolate:DF159 Raw sequence reads. Quercus robur isolate:DF159

TITLEOak powdery mildew infestation during the second shoot flush is accompanied by an extensive but not sufficient defense responseABSTRACTOaks show alternating endogenous rhythmic growth patterns of root and shoot flushes. In a temperate climate, the oak trees display one to three shoot flushes (SFs) per year. As oak powdery mildew infection is commonly higher during the second than the first SF, we asked in a field setting with clonal oak trees, how the oak leaf responds to the pathogen.Powdery mildew infection was higher during 2nd than the 1st SF, but leaf herbivory was not affected. Powdery mildew infection not only elicited a defense response in oak that involved upregulation of pathogenesis related genes, but also led to the downregulation of genes encoding photosystem I and II, indicative of impaired photosynthesis. Heat shock protein and xyloglucan ETH expression were higher, but acid phosphatase and chitinase lower in a site with more sandy soil. Leaf aging led to higher WRKY transcription factor, but lower cyclin, kinesin and expansin gene expression.The timing of leaf growth plays a crucial role for the pathogen challenge of oak leaves, and their capacity to activate plant defense responses during the 2nd shoot flush is not sufficient to stop powdery mildew infection.