Bacillus amyloliquefaciens alters the diversity of volatile and non-volatile metabolites and induces the expression of defence genes for the management of Botrytis leaf blight of Lilium under protected conditions

Abstract

Lilium leaf blight induced by Botrytis cinerea is a major threat in the cultivation of Lilium in the Nilgiris province of Tamil Nadu, India under protected conditions. The present study aims to understand bipartite and tripartite interactions between B. cinerea, Lilium and B. amyloliquefaciens to develop a cost-effective antagonist to manage Botrytis leaf blight. The in vitro antagonism by B. amyloliquefaciens (VB7) suppressed the mycelial growth of B. cinerea by up to 46%. Foliar application of B. amyloliquefaciens (VB7) colonized the phylloplane within 48 h and prevented conidial germination of B. cinerea. Biofilm on the leaf surface colonized the conidia of B. cinerea (SEL). The colonized conidia were parasitized by bacterial cells, resulting in shrinkage. The bipartite interaction between B. amyloliquefaciens (VB7) and mycelial biomass of B. cinerea as sole carbon source produced volatile and non-volatile antifungal compounds. Tripartite interactions between Lilium leaf, B. amyloliquefaciens (VB7) and conidia of B. cinerea produced five different non-volatile antifungal and antibacterial compounds. Expression of defence genes through qRT-PCR analysis indicated that the transcript level of PAL, PR 10 and ascorbate peroxidase (APX) were triggered in Lilium plants treated with B. amyloliquefaciens (VB7), challenged against B. cinerea (SEL). Bulb dipping and soil drenching along with foliar application suppressed Botrytis leaf blight and increased Lilium stem yield under protected conditions.