Isolation,identification,and biocontrol potential of antagonistic actinomycetes against tea root rot caused by Fusarium cugenangense
To discover actinomycete resources with an antagonistic effect on the root rot of Camellia sinensis,a strain JK-13 with strong antagonistic activity against the tea root rot pathogen Fusarium cugenangense was screened from rhizosphere soil of C.sinensis.Strain JK-13 was identified as Streptomyces gelaticus based on morphological,physiological,and biochemical characteristics,and 16S rRNA sequence analysis.The results of the plate confrontation test showed that JK-13 had a high inhibition rate of 67.06％against F.cugenangense,demonstrating good broad-spectrum antagonistic ability toward various pathogenic fungi.In addition,strain JK-13 inhibited the growth of pathogenic fungi by producing volatile and non-volatile organic compounds,metabolites,and extracellular enzymes such as starch hydrolase,cellulose hydrolase,and β-1,3-glucanase.Light microscopy observation revealed that the pathogenic mycelium appeared branched,constricted,distorted,deformed,and intertwined after confrontation culture for five days.Fermentation conditions were optimized to increase the content of active metabolites and the inhibition rate of strain JK-13 against pathogen F.cugenangense.The results of fermentation condition optimization showed that the most suitable carbon source,nitrogen source,and inorganic salt for growth were maltose,(NH4)2SOi,and KC1,respectively.The optimal fermentation medium formula was millet 10 g/L,maltose 10 g/L,(NHi)2SO4 5 g/L,KC1 2.5 g/L,and CaCO3 3 g/L.The inhibition rate of the sterile fermentation filtrate of strain JK-13 against F.cugenangense was 51.03％,an increase of 12.26％compared to the initial culture condition.Therefore,S.gelaticus JK-13 has good development value and application potential in the disease management of tea root rot.
tea root rotFusarium cugenangenseStreptomyces gelaticusbiological control
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