Fungal diversity in citrus fruit at different ripening stage
Orange is one of the main fruits in the world. Postharvest fruit decay is very common at the later stage of citrus growth, transportation and storage and the decay rate usually is 20%-30%, even up to 50%, which causes great losses. Fungi are the main causes of decay including Penicillium italicum, P. digitatum, Alternaria citrus, Collectotrichum gloeosporioides, Diplodianata lensis, Phomopsis cytosporella and Oosporacitri aurantii etc. There is fungal resource even in the healthy orange. In order to clarify the fungal community in fruit, the fungal diversity in the rind and the flesh of Wanmi No 1 citrus fruit samples at growth, ripening and storage stage was examined by Illumina MiSeq sequencing technique. Through analyses of OTUs with abundance, diversity index, and community structure at the order and genus level, we found that there was higher extend of fungal diversity in rind than in flesh. The dominant genera were different at different stage, with Medicopsis and Collectotrichum for the rind at the growth stage, Collectotrichum for the ripening stage, and Botrytis, Erythrobasidium and Strelitziana for the storage stage, while they were Penicillium and Cladosporium at the growth stage, Botrytis at the ripening stage, Penicillium and Alternaria at the storage stage in the flesh. 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 various pattern suggest that the postharvest fruit decay should be a result of interaction of the endopytic fungi.