Suppression of clubroot (Plasmodiophora brassicae) development in Brassica campestris sp. chinensis L. via exogenous inoculation of Piriformospora indica

The aim of the current study is to contribute to the basic understanding of Piriformosporaindica–Brassica campestris sp. chinensis interactions and to assess its impact on clubroot. This study revealed that P. indica, plant-root-colonizing fungus of Basidiomycetes, is capable to reduce the formation of clubroot in B. campestris sp. chinensis which is extremely susceptible to the root pathogen Plasmodiophora brassicae. Roots of the P. brassicae-infected plant were colonized with P. indica, as demonstrated by staining technique and microscopy. Like that, enhanced biomass was observed in P. indica co-inoculated plants by comparing with plants grown without P. indica as well as the plants infected with the pathogen only. Co-inoculation of the plant with both P. indica and P. brassicae reduced gall formation up to 61.60% by comparing plants infected with only P. brassicae as shown by the disease index. Higher level of flavonoids was also observed in P. indica inoculated plants which contribute to enhancing the plant immune system. Thus, a hypothesis was proposed that P. brassicae development in B. campestris sp. chinensis plants could be delayed with the inoculation of P. indica. Expression of P. brassicae genes which were differentially expressed during disease development was monitored using quantitative polymerase chain reaction and was corroborated with delayed pathogen development. The results suggest that P. indica and perhaps other beneficial endosymbionts could be an effective tool for the management of clubroot infection.