Grapevine Leaf Elicitor Activation

Discs of grapevine leaves from greenhouse cuttings were first vacuum-infiltrated with water, then floated on water (lower leaf surface facing the solution) during 3h before adding elicitor solutions. Discs were treated with the various chitosans (1 mg/mL), COS-OGA (62.5 mg/L) or water (as control) and harvested 20 min post-treatment. MAPKs activation was detected after immunoblotting of the extracted proteins using anti-p42/44-phospho-ERK antibody (Cell Signaling, Danvers, MA), as previously described (Brulé et al., 2019 (link); De Bona et al., 2019 (link)). Transfer quality and homogeneous loading were checked by Ponceau red staining.