以红富士苹果为试材,研究苹果果实日灼后色素、多酚、类黄酮、可溶性糖、脯氨酸和相对电导率等指标的变化.结果表明,日灼后,果皮主要色素花青苷和叶绿素被高温和强光破坏,主要通过提高上游基因MdPSY、MdPDS的表达量来促进类胡萝卜素含量升高,并通过多酚向醌类物质的转化以保护果皮免受强光的胁迫.在果皮白化时,相对电导率和MDA无显著变化,但O2-在果皮白化时开始大量积累,从而诱发体内活性氧清除酶SOD、POD、CAT活性显著升高,以及AsA和GSH含量增加,以清除过多的活性氧,减轻对细胞的伤害作用;在果皮褐化时,胁迫程度加重,相对电导率、MDA和O2-显著升高,SOD、POD和CAT活性显著降低,且AsA和GSH的含量下降.说明果皮白化时期,细胞膜尚未受到损伤,保护酶活性较高,保护物质含量升高,保护系统处于活跃状态,为日灼防治的关键时期.%Using the apples of cultivar Fuji as materials,the changes of some physiological and biochemical indicators,such as pigments,polyphenols,flavonoids,soluble sugar,proline,relative conductivity,MDA,superoxide anion free radical,protective enzymes and AsA-GSH were analyzed in two types of sunburned apple fruits.After sunburn,the contents of chlorophyll and anthocyanin decreased,the carotenoid and polyphenols contents increased,and the expression levels of MdPSY and MdPDS increased greatly.On the stage of peel whitening,in order to protect the cytomembrane from the damage by superoxide anion free radical,the activities of SOD,POD and CAT,the contents of AsA and GSH content increased,while in the stage of peel browning,indicators mentioned above decreased.It was concluded that during the stage of peel whitening,cytomembrane was intact and protective enzymes activity and some protective substance contents were higher,so peel whitening was the crucial stage for prevention and control apple sunburn.
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