The inhibitory effect of alfalfa epiphytic bacteria on Clavibacter as the causal agent of wilt disease

Due to indiscriminate use of chemical pesticides and its impact on the environment, other methods including the use of epiphytic and endophytic bacteria to control pathogens is highly regarded. Since Medicago sativa is the most important forage crop in Iran and many parts of the world, this study was aimed to evaluate the inhibitory effect of alfalfa epiphytic bacteria on the causal agent of wilt disease in in-vitro.
Undiseased alfalfa leaf samples were collected from different parts of Hamedan province, before its flowering. After isolating epiphyte bacteria from alfalfa fields, the antagonistic effect of isolates was investigated by measuring the diameter of the inhibition zone against alfalfa bacterial wilt. Protein extraction was performed to assess the pattern of protein bands and the variety of the strains. Biochemical tests and PCR were used to identify the isolates.
A total of 30 epiphyte bacteria were isolated from alfalfa shoots. Bacterial isolates were identified as Bacillus, Pseudomonas, and Xanthomonas, based on biochemical, physiological and morphological tests. The highest bactericidal effect was related to isolating No. 16 and the lowest to isolates No. 13, and No. 6, respectively. Using molecular and dendrogram methods, isolate No. 16 was most closely related to Pseudomonas monteilii.
Epiphytic bacteria isolated in this study showed a good inhibitory effect against alfalfa wilt in vitro. This can be promising for the biocontrol of this disease. However, further studies are needed to prove the efficacy of the isolates in field conditions.