Systemic resistance in sugar beet eliciated by non-pathogenic, phyllosphere-colonizing Bacillus pumilus and B. subtilus against the pathogen Cercospora beticola Sacc.

A total of 10 Bacillus subtilis (7) and Bacillus pumilus (3) isolates from sugar beet phyllosphere were evaluated for its biocontrol activity against sugar beet cercospora leaf spot disease (CLS) under greenhouse and field conditions compared to the fungicide Topsin M70. PR-related proteins, chitinase, β-1,3-glucanase, peroxidase, polyphenol oxidase as well as indol acetic acid were determined in treated and untreated sugar beet plants. Under greenhouse conditions the reduction in disease severity caused by B. subtilis and B. pumilus treatments ranged from 73.33 80% and 80 83% respectively. Under field conditions the reduction ranged from 56.18 to 81.27% and 62.55 to 81.27% from B. subtilis and B. pumilus respectively. The levels of the determined PR proteins significantly increased in all the treated plants either with B. subtilis or B. pumilus. In addition, the levels of IAA were higher in the treated plants compared to the untreated plants. The sucrose percentage increased in the treated plants compared to the infected untreated control. The present study suggested the role of Bacillus subtilis and Bacillus pumilus in inducing plant acquired resistance.