Biocontrol potential of cell-free supernatant of Paenibacillus chitinolyticus against Plasmodiophora brassicae in two important Brassica species

Abstract

Plasmodiophora brassicae is a serious threat to Brassica crops worldwide, resulting in substantial economic losses for growers, with the challenge of control persisting. Biocontrol with chitinolytic bacteria producing chitinase is gaining attention as a natural alternative to chemicals. This approach is favored due to the essential role chitinases play in protecting against chitin-containing pathogens. Given that chitin is a major component in the resting spores of P. brassicae and plays a crucial role during pathogenesis, it is probable that Paenibacillus chitinolyticus, producing a high level of chitinase, could suppress P. brassicae by targeting chitin in a critical stage of this pathogen’s life cycle. Our research aimed at evaluating the effect of various applications of P. chitinolyticus on clubroot suppression in two economically important Brassica species: Chinese cabbage and rapeseed. The effectiveness of the cell-free supernatant (CFS) of an endemic strain of P. chitinolyticus from the Czech Republic at five different time points was studied in the greenhouse by measuring the disease severity index. The results showed that early application of P. chitinolyticus decreased the disease index significantly within both plants. Additionally, in both plants, P. chitinolyticus increased shoot dry weight to a great extent. In conclusion, the CFS of P.chitinolyticus has significant antagonistic activity against clubroot in Chinese cabbage and rapeseed in the early developmental stages of clubroot occurrence and holds the potential as a biofertilizer as well as bioprotectant agent in clubroot management of P. brassicae.