Paenibacillus terrae PY8 controls Botrytis cinerea and modifies the endophytic microbial community of the medicinal plant, Paris polyphylla

Abstract

Huachonglou (Paris polyphylla Smith var. chinensis (Franch.) Hara) is an important traditional Chinese herbal medicine. Botrytis cinerea is a plant pathogen that causes significant economic losses of P. polyphylla. Presently, chemical fungicides are the primary means of effective control of gray mold caused by B. cinerea. As a safer and greener control method, biocontrol agents (BCAs) for gray mold of P. polyphylla are very important. In the present study, a biocontrol agent, Paenibacillus terrae PY8, was isolated from the endophytic microbial community of leaves of the medicinal plant, Paris polyphylla. PY8 significantly reduced gray mold infections by Botrytis cinerea and additionally increased P. polyphylla yield and the level of polyphyllin Ⅰ and Ⅱ of P. polyphylla detected in rhizomes. An analysis of the endophytic microbial community of leaves of P. polyphylla indicated that the foliar application of P. terrae PY8 favorably altered the composition and structure of the endophytic community in P. polyphylla by decreasing the total abundance of potential plant pathogenic fungi. The effect of biocontrol agents on the endophytic microbiome may represent a new criterion for evaluating biocontrol agents in the future. Results of the present study provide theoretical support for the field application of PY8 on P. polyphylla for the control of gray mold.