Regulation of endogenous hormones on post-harvest senescence in transgenic broccoli carrying an antisense or a sense BO-ACO 2 gene.

摘要

Transgenic broccoli with a sense (S line) or an antisense (AS line) BO-ACO 2 gene shows delayed postharvest senescence. Since endogenous phytohormones play the main role in plant senescence, it is important to elucidate how phytohormones change and affect postharvest senescence in transgenic broccoli. Thus, regulation effects of endogenous ethylene, abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellic acid (GA3) and zeatin riboside (ZR) on immaturity senescence were analysed in postharvest transgenic broccoli heads. Delayed onset of floret yellowing in transgenic broccoli was mainly attributed to reduced ethylene production. Compared with the earlier senescence in the control, transgenic broccoli showed increasing concn. of ZR during the storage time and reduced levels of ABA and IAA in florets. GA3 was 1 of the possible factors responsible for the almost 5-day storage life in the AS line, but did not seem crucial for floret senescence in the S line. It is concluded that the BO-ACO 2 gene is directly involved in ethylene biosynthesis and at the same time regulates the metabolisms of plant hormones ABA, IAA, GA3 and ZR. Rebalancing of the mechanism of plant hormones in florets of transgenic broccoli due to the integrated BO-ACO 2 gene was closely associated with retardation of postharvest senescence.