PG和LOX对采后番茄果实软化及细胞超微结构的影响

Effects of PG and LOX on Fruit Softening and Ultrastructure Changes of Postharvest Tomato Fruit

以番茄 (Lycopersiconesculentum)品种‘丽春’为试验材料研究了果实采后多聚半乳糖醛酸酶 (PG)和脂氧合酶 (LOX)的活性变化与果实硬度的关系 ,并观察了细胞超微结构的变化。结果表明 ,随着果实采后呼吸强度和乙烯释放量不断增加 ,PG和LOX活性迅速增加 ,而果实硬度逐渐下降。呼吸强度和LOX活性高峰出现在发白期 (BR) ,而乙烯释放量高峰延迟至转色期 (TU)。PG活性随着果实的成熟逐渐增加 ,而LOX活性在发白期之后保持较高水平。分别用外源LOX和LOX加底物处理番茄组织切片 ,发现组织细胞的衰老进程加速 ,进而导致细胞膜瓦解、胞壁纤维松弛以及细胞器空胞化。PG和LOX都与果实的后熟软化有关 。

Tomato( Lycopersicon esculentum cv.Lichun)was used to inverstigate the effects of polygalaturonase(PG)and lipoxygenase(LOX)on ripening and senescing of fruit.The result indicated that respiration rate and ethylene production increased after harvest,and PG activity and LOX activity rose rapidly,while the firmness of fruit gradually decreased.The respiration rate and LOX activity reached their peaks at BR(Breaker stage)and ethylene formation delayed until TU(Turning stage),then LOX activity kept the high level until RED(red)stage.PG activity kept rising until RED stage.Treatment with exogenous LOX,LOX and its substrate led to the breakdown of membrane system and the relaxation of the fibril in cell wall and the gradual disappearance of the cell organelles,promoting cell senescence.