Characterization of Botrytis cinerea , the causal agent of tomato grey mould, and its biocontrol using Bacillus subtilis

Botrytis cinerea infects more than 1400 plant species globally, resulting in severe damage pre- and post-harvest. This study aimed to isolate and identify B. cinerea from tomato plants from local greenhouses and assess the inhibitory capacities of local Bacillus strains against B. cinerea. Various B. cinerea strains isolated from infected tomato plants exhibited characteristic symptoms. The ITS sequences and phylogenetic analysis of isolates exhibited 99 % homology with B. cinerea. Pathogenicity tests on healthy tomato vegetative growth or detached leaves using QB13, QBuk1, and QUna fungal isolates fulfilled Koch's postulates. Symptomatic characteristics resulting from the artificial inoculations of tomato grey mould closely resembled those of the original diseased leaves and stems collected from the field after 7 DPI when seven strains of Bacillus subtilis (64C1, 88D, 65D, 64C2, 41D1, 23A2, and 102) tested in-vitro against B. cinerea demonstrated that all of Bacillus subtilis isolates displayed notably strong antagonistic effects against B. cinerea. Mycelial growth inhibition ranged from 37 % (isolate 65D) to 60 % (isolate 102) compared to the untreated control. The most substantial inhibitory effects against B. cinerea were statistically observed with isolates 88D and 102, which exhibited inhibition rates of 58 % and 60 %, respectively. Morphological and molecular identification and pathogenicity analysis revealed that all 20  B. cinerea isolates obtained from infected tomato plants from greenhouses exhibited a highly pathogenic effect on tomato plants. This study states the basis for developing natural biocontrol agents to combat grey mould caused by B. cinerea on tomato plants.