The present study investigated resistance against Botrytis cinerea after heat shock treatment in melon plants. Heat shock at 50 degrees C for 20 s 0-24 h before inoculation resulted in maximal B. cinerea symptom reduction and peroxidase gene expression, which peaked 12 and 72 h post-treatment and decreased 24-48 h post-treatment, suggesting pathogenesis-related protein expression priming. Hot water dipping did not directly inhibit mycelia growth. Plants treated with 2-benzisothiazol-3(2H)-one 1,1-dioxide, which induces systemic acquired resistance, demonstrated higher peroxidase gene expression but no B. cinerea resistance, indicating possible involvement of additional novel mechanisms in heat shock-activated resistance of melon against B. cinerea. (C) 2011 Elsevier Ltd. All rights reserved.