柑橘内生真菌的分离鉴定及其发酵产物对柑橘溃疡病菌的抑制活性

本研究从柑橘抗病品种的健康植株不同组织中分离纯化和鉴定内生真菌,并测定其发酵产物对柑橘溃疡病菌的抑制活性,以明确柑橘抗病品种中内生真菌的组成及其产抗柑橘溃疡病菌活性代谢产物的潜力,为柑橘溃疡病抗菌剂的开发奠定基础.该研究通过组织培养法分离内生真菌,采用形态学和分子生物学方法对其进行鉴定;基于前期的拮抗预试验结果,选取代...

Isolation and identification of endophytic fungi from citrus cultivars and their inhibitory activity against Xanthomonas citri subsp. citri causing citrus canker

In this study, to provide a basis for the controlling of citrus canker disease, endophytic fungi from different citrus disease-resistant cultivars were isolated and identified by using a tissue culture method, and the method based on morphology combined with molecular biology, respectively. Representative endophytic fungi were selected based on the antagonism results in pre-experimental, to determine the antibacterial activity with their ethyl acetate extracts from the fermented culture against pathogen Xanthomonas citri subsp. citri, using a toxic medium coating method. The results were as follows:(1)A total of 72 endophytic fungi were obtained from different citrus cultivars and classified into 14 genera. Fungal isolates belong to phylum Ascomycota and Basidiomycota. The frequent genera were Colletotrichum, Guignardia, Alternaria and Fusarium.(2)The diversity indices of endophytic fungi from different citrus as follow: Citrus unshiu Marc.(Guilin)> C. reticulata Blanco cv. Shatangju(Guilin)> C. reticulata Blanco cv. Shatangju(Wuzhou).(3)The diversities indices of endophytic fungi were different, which were isolated from different tissues of citrus associated with different geographical location. The similarity of endophytic fungi in the citrus samples collected from Wuzhou and those from Guilin was low.(4)The antibacterial activity of ethyl acetate extracts from the fermented culture of 30 endophytic fungi were determined against pathogen Xanthomonas citri subsp. citri in vitro assay. Most of their extracts exhibited significant inhibition. Among them, the MIC values of dominant genera, specific genera and shared genus were 0.312 5-10 mg·mL^-1, 0.156-5 mg·mL^-1 and 0.312 5-2.5 mg·mL^-1, respectively. The results indicate that the endophytic fungi in citrus disease-resistant cultivars are rich in diversity, and most of their extracts exhibit inhibition against X. citri subsp. citri. The antibacterial activity of specific genera is generally better than the dominant genera, and all of the strains in the shared genus Fusarium displayed significant inhibition against X. citri subsp. citri.