不同时期的柑橘果实中真菌种类分析

Fungal community diversity in citrus fruit at different ripening stage

柑橘采后真菌病害发生普遍,对柑橘产业造成了极大的威胁。柑橘体内存在丰富的真菌类群,为了了解柑橘成熟和衰老过程中果实内生真菌的多样性和变化动态,本论文通过MiSeq技术解读真菌ITS区域序列,分别对生长期、成熟期和贮藏期的晚蜜一号果实的果皮和果肉的内生真菌种类进行了分析。发现相比于果肉,果皮中真菌在目和属水平的多样性更为丰富,而成熟期果肉中真菌种类多于果皮。不同生长阶段的两种组织中优势的真菌属也不同,果皮在生长期以Medicopsis和刺盘孢属(Colletotrichum)占绝对优势,成熟期为刺盘孢属,贮藏期以葡萄孢属(Botrytis)、Erythrobasidium和Strelitziana较为常见;而果肉中生长期主要为青霉属(Penicillium)和枝孢菌属(Cladosporium),约占1/4,成熟期半数以上为葡萄孢属,及至贮藏期约90%为链格孢属(Alternaria)和青霉属,其中链格孢属约占2/3。常见植物病原真菌如枝孢菌属(Cladosporium)、巨座壳属(Magnaporthe)、核盘菌属(Sclerotinia)、葡萄孢属(Botrytis)、白粉菌属(Erysiphe)、青霉属(Penicillium)、链格孢属(Alternaria)和镰孢霉属(Fusarium)等在果肉中的数量高于果皮。果肉中存在较大数量的常见植物病原真菌,不同属真菌在不同样品中呈不同的变化动态,暗示采后病变是多种真菌交互作用的结果,采后病害的防治可以提前至开花期。

Postharvest citrus fruit decay, caused by fungi, is a common disease which has great impact on citrus industry. There are diverse fungal communities in citrus fruit under natural conditions. By decoding the sequences of fungal ITS region through IUumina MiSeq sequencing technologies, we analyzed the diversity and dynamic of fungal communities in the find and flesh of Wanmi No 1 citrus fruit samples at the growth, ripening and storage stages. Through analyses of OTU with abundance, diversity index, and community structure at the order and ge- nus level, we found that there was a higher degree of fungal diversity in the rind than in the flesh at both the growth and storage stage, on the contrary, the opposite results were found at the ripening stage of citrus fruit. The dominant genera were different at different stage, with Medicopsis and Collectotrichum in the rind at the growth stage, Collectotrichum at the ripening stage, Botrytis, Erythrobasidium and Strelitziana at the storage stage;~ while in the flesh, Penicillium and Cladosporium accounted for 1/4 of the whole community at the growth stage, Botrytis with more than 50% of the total at the ripening stage, Penicillium and Altemaria accounted for 90% in which 2/3 was Alternaria at the storage stage. The population of plant pathogenic fungi Cladosporium, Magnaporthe, Sclerotinia, Botrytis, Erysiphe, Penicillium, Alternaria and Fusarium in the rind were larger than in the flesh. The large population of fungi and the change pattern in the flesh suggest that the postharvest fruit decay should be a result of interaction of fungi. The results will help us to understand the disease cycles and de- sign control techniques of citrus postharvest fruit decay in advance to flowering stage.