Effects of lipoxygenase and jasmonic acid on ethylene biosynthesis during tomato fruit ripening
Jiping Sheng , Jianrong Ye and Yunbo Luo
ISHS Acta Horticulturae 620: 119-125.
2003
บทคัดย่อ
Jasmonic acid (JA) is a metabolite of lipoxygenase (LOX) and a growth regulator, which has many physiological functions associated with ethylene. To determine the role of LOX and JA in ethylene biosynthesis during tomato fruit ripening, low-ethylene producing fruits from antisense ACC synthase (ACS) transgenic plants (ethylene production is only 0.5%-3.0% of the wild-type fruits) were compared with fruits from wild-type plants. Expression of a gene encodign LOX, TOMIoxB, and relative LOX activtiy increased continuously in transgenic fruit after treated with 1000 uL.L ethephon at room temperature; meanwhile, two kinds of fruit treated with exogeneous JA were examined to determine the role of JA and ethylene in TOMIoxB expression. In wild type fruit, exogeneous JA increased relative LOX activity continuously increased TOMIoxB transcripts, and promoted color change of fruits from green to yellow/orange within 24 hours of treatment. TOMIoxB transcripts decreased almost to zero at 48 hours. However, exogeneous JA had no effect in low ethylene transgenic fruits; no color change was detected within 24 hours; both relative LOX activity and TOMIoxB transcripts ramains unchanged in 24 hours. The effect of LOX on ethylene biosynthesis was less than that on ACC oxidase, sugesting an indirect role of LOX in ethylene biosynthesis. Presence of ethylene appears necessary to affect JA-induced LOX gene expression, suggesting that the JA signal pathway interacts with that of ethylene, and that LOX may play a role in ethylene biosynthesis via JA.