ε-聚赖氨酸对棒状新拟盘多毛孢侵染的番石榴果实抗病性的影响

Effect ofε-Poly-L-lysine on Disease Resistance in Guava Fruit Infected by Neopestalotiopsis clavispora

研究ε-聚赖氨酸(ε-poly-L-lysine,ε-PL)对棒状新拟盘多毛孢侵染所致番石榴果实环斑病发生和抗病物质代谢的影响。以‘西瓜红’番石榴果实为实验材料,以无菌水浸泡处理10 min后接种棒状新拟盘多毛孢的番石榴果实为对照组,以2.0 g/Lε-PL溶液浸泡处理10 min后接种棒状新拟盘多毛孢的番石榴果实为处理组,并在(28±1)℃、90%相对湿度下贮藏7d,每天取样测定果实病斑直径、细胞膜透性、木质素质量分数及抗病相关酶活性的变化。结果发现,与棒状新拟盘多毛孢接种番石榴果实相比,ε-PL可以降低棒状新拟盘多毛孢接种番石榴果实的病斑直径和细胞膜透性,保持较高的果实木质素质量分数及β-1,3-葡聚糖酶、肉桂酸-4-羟化酶、4-香豆酰辅酶A连接酶、过氧化物酶、苯丙氨酸解氨酶、几丁质酶和肉桂醇脱氢酶等抗病相关酶活性。因此认为,ε-PL通过诱导提高采后番石榴果实木质素水平和抗病相关酶活性,维持果实细胞膜结构的稳定,进而增强番石榴果实采后抗病性,从而延缓由棒状新拟盘多毛孢侵染所致番石榴果实环斑病的发生。

The effect ofε-poly-L-lysine(ε-PL)treatment on the occurrence of postharvest fruit rot caused by Neopestalotiopsis clavispora and disease resistance-related substance metabolism in guava were explored.Freshly harvested guavas(cv.Xiguahong)were soaked in sterile distilled water as a control or 2.0 g/L ε-PL solution for 10 min,inoculated with N.clavispora,and then stored at(28±1)℃and a relative humidity of 90%for up to seven days.During the whole storage period,lesion diameter,cell membrane permeability,lignin content and disease resistance-related enzyme activities in guava fruit were measured every day.The results showed that compared with the control group,ε-PL could reduce the lesion diameter and cell membrane permeability,and maintain higher lignin content and higher activities of disease resistance-related enzymes including β-1,3-glucanase,cinnamate-4-hydroxylase,4-coumarate CoA ligase,peroxidase,phenylalanine ammonia-lyase,chitinase and cinnamyl alcohol dehydrogenase.Therefore,we conclude that ε-PL enhanced the lignin level and the activities of disease resistance-related enzymes and consequently maintained cell membrane stability,which in turn enhanced the postharvest disease resistance of guavas and delayed the occurrence of guava fruit rot caused by N.clavispora.