β-1,3-Glucanase Gene Expression in Grapevine Leaves as a Response to Infection WithBotrytis cinerea

When inoculated with a B. cinerea conidial suspension, grapevine (Vitis vinifera L. cv. Chardonnay) leaves, developed a necrotic area whose size increased over time. Seven days after the infection, newly synthesized acid-soluble proteins were revealed in the healthy part of the inoculated leaves. Immunodetection procedures identified, among the numerous newly synthesized proteins, four acidic proteins which cross-reacted with a tobacco PR2a (β-1,3-glucanase) antiserum. One of these four isoforms, a protein with an apparent molecular weight of 34 kDa and an isoelectric point of 5.7, was microsequenced and revealed strong similarities with the same part of β-1,3-glucanase sequences from many plants (tobacco, tomato, bean . . .). The kinetics of grapevine β-1,3-glucanase expression pattern in response to B. cinerea inoculation was studied at the transcription and the translation levels. Northern blot hybridization showed that β-1,3-glucanase mRNAs strongly accumulated in the leaves from day 3 to day 7 postinfection, with a maximum rate observed at day 5. The β-1,3-glucanase proteins were detected at day 3 and increased up to day 7. The potential implication of β-1,3-glucanases in the grapevine-B. cinereainteraction is discussed.