Guangxi Zhiwu (Jan 2023)
Bioactivity evaluation of endophytic fungi of Polygala fallax and identification of HNLF-44 strain
Abstract
The medicinal plant Polygala fallax has a variety of biological activities. In order to fully develop the endophytic fungi resources of the wild P. fallax and to obtain the culture-endophytic fungi strains with an anti-phytopathogenic fungi and antioxidant activities, the endophytic fungi of P. fallax were taken as the research object, the antifungal activity of the endophytic fungi against six kinds of phytopathogenic fungi was detected by the plate confrontation method; and the antioxidant activity of endophytic fungi was evaluated by measuring the DPPH free radical scavenging ability and total reducing ability of endophytic fungi fermentation broth. Finally, the endophytic fungi strains with strong antifungal and antioxidant activities were then analyzed by the morphological traits and the flanking ITS sequencing. The results were as follows: (1) In the antifungal experiment, there were two endophytic fungi of P. fallax had obvious antifungal activities on six kinds phytopathogenic fungi of Fusarium oxysporum f. sp. cubense, Phyllosticta zingiberi, Diaporthe citri, Mycosphaerella fijiensis, Fusarium solani, F. oxysporum, and the inhibition rates ranged from 50.3% to 91.4%. Among them, HNLF-5 strain had a good effect antifungal activity against Diaporthe citri, with a inhibition rate of 73.2%, and HNLF-44 strain had a good effect antifungal activity against Fusarium oxysporum f. sp. cubense, with a inhibition rate of 91.4%. (2) In the experiment of antioxidant activity, the endophytic fungal fermentation broth had good antioxidant activity, the DPPH clearance rate was above 80%, and the total reducing ability absorbance value ranged from 0.279 2 to 0.748 8. (3) It could be seen from the strain identification results that the HNLF-44 strain with antifungal activity was Alternaria sp. fungus. This study indicates that the endophytic fungi of Polygala fallax have a good ability of inhibiting plant phytopathogenic fungi and antioxidant activity, which lays the foundation for the subsequent exploration of potential new antifungal and antioxidant substances from P. fallax endophytic fungi.
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