Sensibilité des grappes au milidiou: nouvelles données microscopiques et biochimiques | Susceptibility of grape clusters to downy mildew
2012
Gindro, K. | Alonso-Villaverde, V. | Voinesco, F. | Spring, J.-L. | Viret, O. | Dubuis, P.-H., Station de recherche Agroscope Changins-Waedenswil ACW, Nyon (Switzerland)
Grape clusters of different genotypes, including Vitis vinifera cvs Chasselas and Merlot, and two interspecific grape varieties, Solaris and 2091 (Gamaret x Bronner) were inoculated with Plasmopara viticola at three developmental stages (BBCH 53, 69 and 75). Samples were examined by scanning electron microscopy and synthesis of stilbenic phytoalexins was measured. At BBCH 53, zoospores germination was observed on all tested cultivars and three types of functional stomata were set up. At this stage, resistant cultivars produced a significant accumulation of toxic stilbenes, which stopped the further development of downy mildew. At BBCH 69 and 75, stomata are no more functional and none of P. viticola infection was successful. This result is confirmed by the absence of stilbenes induction at these stages on resistant grapevine cultivars. The structural changes in stomata anatomy during cluster development induce the onset of ontogenic resistance.
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