短波紫外线照射对苹果采后灰霉病抗性诱导作用

Effects and Mechanism of UV-C Treatments on Control of Botrytis cinerea in Postharvest Apples

为探究短波紫外线(ultraviolet C,UV-C)照射对苹果采后灰霉病的防治效果与抗性诱导机理,以红富士苹果为材料,采用剂量分别为3.5、7.0、10.5 k J/m2的UV-C(280 nm)进行照射,常温条件下放置2 d后接种灰葡萄孢菌,以不经UV-C照射直接接种灰葡萄孢菌的果实作为对照。结果表明:照射剂量为3.5 k J/m2和7.0 k J/m2的UV-C照射可显著降低果实灰霉病的发生率,抑制病斑直径的扩展(P<0.01),其中照射剂量为7.0 k J/m2 UV-C处理的效果更好;而照射剂量为10.5 k J/m2的UV-C照射处理在接种后贮藏前期对病害有抑制作用,后期却加快病害发展。3.5 k J/m2和7.0 k J/m2 UV-C处理能诱导苹果果实几丁质酶、β-1,3-葡聚糖酶、过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)等抵御酶活性的提高,诱导酚类物质的合成,进而增强果实的抗病性,其中7.0 k J/m2 UV-C处理诱导效果更明显,与对照差异显著(P<0.01)。10.5 k J/m2 UV-C照射仅在接种后前期诱导POD、PPO、PAL和几丁质酶的活性迅速上升,提高总酚和类黄酮含量,但对β-1,3-葡聚糖酶活性没有诱导作用。

This study aimed to investigate the effects and mechanism of UV-C treatments on control of botrytis in postharvest apples. Red Fuji apple fruits were treated by UV-C at different doses(3.5, 7.0, and 10.5 k J/m2) and, two days later at normal temperature(20 ± 1) ℃, inoculated with conidial suspension of Botrytis cinerea, and inoculated samples without UV-C treatment were used as control. The results showed that UV-C treatments at 3.5 and 7.0 k J/m2 significantly decreased the incidence of gray mold rot, and effectively suppressed the expansion of lesions caused by B. cinerea, and the suppression effect of UV-C treatment at 7.0 k J/m2 UV-C on gray mold was better than at 3.5 k J/m2. However, UV-Ctreatment at 10.5 k J/m2 had an adverse effect on gray mold of apple fruits only after inoculation for the earlier days while at the later stage after inoculation, and even increased morbidity of fruits and promoted the expansion of lesions. In addition, the activities of chitinase(CHT), β-1,3-glucanase(GLU), peroxidase(POD), polyphenol oxidase(PPO) and phenylalanine ammonia-lyase(PAL) of apple fruits were promoted remarkably by UV-C treatments at 3.5 and 7.0 k J/m2, and phenolics content was also increased significantly. The promoting effects of UVC-treatment at 10.5 k J/m2 on those defense enzymes activities and phenolics content was found only in the first several days after inoculation.