TY - JOUR T1 - Methyl Jasmonate and 1-Aminocyclopropane-1-Carboxylic Acid Interact to Promote Grape Berry Abscission JF - American Journal of Enology and Viticulture JO - Am. J. Enol. Vitic. DO - 10.5344/ajev.2014.14038 SP - ajev.2014.14038 AU - Lorena Uzquiza AU - Pedro Martin AU - James R. Sievert AU - Mary Lu Arpaia AU - Matthew W. Fidelibus Y1 - 2014/08/18 UR - http://www.ajevonline.org/content/early/2014/08/13/ajev.2014.14038.abstract N2 - The application of methyl jasmonate (MeJA) or ethephon, an ethylene releasing agent, to Thompson Seedless grapes can reduce fruit detachment force (FDF) and promote the development of dry stem scars on berries, possibly improving the quality of machine harvested grapes. However, the amount of MeJA or ethephon needed to stimulate abscission may be prohibitively expensive and result in excessive residues. Thus, experiments were conducted to determine whether MeJA might interact with 1-aminocyclopropane-1-carboxylic acid (ACC), a natural biochemical precursor of ethylene, to promote abscission-related processes, and possibly reduce the amount of MeJA needed. In a preliminary trial, MeJA (672 and 1,344 mg/L) interacted with ACC (500 and 1,000 mg/L) to reduce FDF by 25% to 70% compared with non-treated grapes. However, MeJA and ACC did not interact to affect preharvest fruit drop, though treatment with 672 or 1,344 mg/L MeJA, caused 16% to 23% drop by 3 days after treatment (DAT). In a second trial, grapes treated with MeJA singly, or with ACC, produced ethylene which peaked at 1 DAT, remained elevated at 2 DAT, and declined rapidly thereafter, whereas grapes treated only with ACC maintained moderately elevated ethylene production throughout the 10-day study. Treatment with ACC or MeJA reduced FDF within 1 or 2 DAT, respectively. By 2 DAT, berries began to abscise from MeJA-treated clusters, regardless of whether they were also treated with ACC, but on 3, 4, and 10 DAT, ACC and MeJA interacted to greatly promote preharvest fruit drop. Moreover, the combination of ACC and MeJA also promoted dry stem-scar development. Thus, coapplication of MeJA and ACC is more effective at stimulating grape abscission-related processes than either compound applied singly. ER -