Effect of Jasmonate and Salicylic Acid Treatments on Fruit Maturation in Japanese Persimmon

Abstract

Jasmonic acid (JA) is widely distributed in higher plants and its derivatives are considered novel plant hormones, while salicylic acid (SA) regulates various physiological responses including fruit ripening through the production of reactive oxygen species and ethylene in some plant species. To elucidate the involvement of JA and SA in the maturation of persimmon fruit (Diospyros kaki Thunb. cv. Fuyu), the effects of methyl jasmonate (MeJA), SA, ethrel and hydrogen peroxide (H₂O₂) on fruit maturation were evaluated in this study. H₂O₂ most strongly enhanced coloration as determined by “color chart”, followed in order by MeJA and SA, whereas ethrel did not show any effect on color promotion. H₂O₂, MeJA and SA also increased lycopene and decreased chlorophyll concentration in the skin at harvest. Severe fruit drop was caused by both H₂O₂ and ethrel treatments, but there was almost no effect of MeJA treatment at 500 ppm. MeJA at 500 ppm did not soften the fruit flesh at all, although H₂O₂ and ethrel softened the fruit significantly. Persimmon fruit treated with MeJA emitted about 10 times more ethylene than the control, and SA treatment hastened the ethylene emission peak about 6 days compared to the control. Thus, JA and SA appear to be involved in maturation of persimmon fruit, possibly through the production of endogenous ethylene and reactive oxygen species. MeJA is a promising chemical for enhancing coloration of persimmon fruit.