Controlling of Leaf Mustard Yellow Disease by Two Compatible Bacillus species   

Leaf mustard yellows caused by Fusarium oxysporum f. sp. rapae, is one of the major fungal disease-causing huge losses in the field. Biological control is thought to be effective method to control the disease. Compatible interactions between Plant-Growth Promoting Rhizobacteria (PGPR) are expected to provide better effective consortium. Two PGPR, Bacillus velezensis (BV) and Bacillus subtilis (BS) were originally isolated from a Chinese medicine called cooked Rehmannia. The BS strain positively interacted with the BV strain by promoting growth of the BV strain in both solid and liquid media. In greenhouse assays, both the BS and BV strains were able to reduce the disease severity of leaf mustard yellows. Moreover, one of their mixed cultures provided better protection against the disease than individual strains. Furthermore, the bacterial interaction consistently increased plant growth in dry weight, root length, plant height and fresh weight.