پراکنش Xanthomonas phaseoli pv. phaseoli عامل سوختگی معمولی باکتریایی لوبیا در ایران

Legumes, including beans, are one of the most important sources of protein in the diet of many people in different countries, including Iran. Common bacterial blight of beans caused by the Xanthomonas phaseoli pv. phaseoli is one of the most destructive seed-borne diseases on beans. During the years 2022 and 2023, samples were collected from bean fields in the majority of regions across Iran, including Fars, Kohgiluyeh-Boyer-Ahmad, Lorestan, Markazi, Qazvin, Chaharmahal and Bakhtiari, and Kermanshah provinces. Bacterial isolation was conducted in accordance with standard bacteriological procedures on nutrient agar (NA) medium. After 48-72 hours, pale-yellow, domed, and circular colonies were appeared on NA medium. The results of biochemical tests revealed that all bacterial strains are positive for hydrolysis of aesculin, tween 80, casein and induce of hypersensitive reaction on tobacco plants, while they were negative for gram, anaerobic growth and oxidase tests. The results of biochemical tests showed that the all bacterial strains are belong to Xanthomonas spp. The primer pair Xc-lip-F2/Xc-lip-R2 specific for Xanthomonas spp. directed the amplification of the expected 777 bp fragment in all bacterial strains. Phylogenetic analysis using sequencing of four housekeeping genes (atpD, dnaK, gyrB, and rpoD) showed that the all bacterial strains obtained in this study belong to X. phaseoli pv. phaseoli. The pathogenicity test for all bacterial strains was conducted by spraying bacterial suspension on bean plants in greenhouse conditions. After two weeks of inoculation, water-soaked lesions with a yellow halo appeared on both the upper and lower surfaces of the leaves. The bacterial strains were isolated again from inoculated plants after showing symptoms, and their identification was carried out using specific Xc-lip-F2/Xc-lip-R2 primers for Xanthomonas. Finally, the biochemical, molecular, and pathogenicity tests indicated that the halo blight agent of beans is present in various provinces of the country.