<div>Background: Common bacterial blight (CBB) caused by Xanthomonas axonopodis pv. phaseoli (Xap) has been recorded as one of the most important seed-borne destructive diseases of beans, affecting its production worldwide. Since chemical compounds cause serious damage to natural ecosystems and in some instances fail in controlling CBB, the use of genetically resistant cultivar is the most economically efficient and environmentally friendly measure in the control of CBB disease. The objective of this study was to assess the resistance reactions of widely grown and popular common bean cultivars against Xap under controlled conditions. 
 
Methods: In this study, 16 dry bean cultivars comprising eight widely grown dry bean varieties, six improved and promising genotypes and two known CBB susceptible varieties, were evaluated for their reaction to the CBB in a completely randomized design with three replications. The reaction of the bean cultivars to Xap was assessed using disease incidence, disease severity, per cent severity index, the area under disease progress curve (AUDPC) and incubation period.&nbsp; 
 
Result: Data analysis indicated that there were highly significant differences (p&le;0.01) among common bean cultivars for CBB disease incidence, disease severity, per cent severity index and AUDPC among cultivars. The cultivated varieties Noyanbey and &Ouml;zmen were identified as resistant cultivars. In addition, SAP6 and BAC6 resistance genes were found in these two cultivars. As a consequence, it was thought that these cultivars could be a potential source of disease resistance for CBB in breeding programs and sustainable, eco-friendly and good agricultural practices.</div>

​​Evaluation of Dry Bean Cultivars in Turkey for Resistance against Common Bacterial Blight Disease

Background: Common bacterial blight (CBB) and halo blight (HB) are among the most destructive bacterial diseases affecting common beans, leading to significant yield and quality losses. The use of resistant cultivars remains the most effective and sustainable management strategy. Identifying the presence of resistance genes and understanding the role of antioxidant enzymes before and after bacterial inoculation are crucial for developing resistant breeding lines. 
 
Methods:&nbsp;This study investigated the presence of resistance genes against Xanthomonas axonopodis pv. phaseoli (Xap) and Pseudomonas savastanoi pv. phaseolicola (Psp) in eight bean varieties (Ozmen, Noyanbey, Akman, Alberto, XAN159, Vax1, Aras 98 and 36K). Additionally, the activities of antioxidant enzymes; Peroxidase (POX) and Catalase (CAT) were evaluated in two selected varieties (Aras 98 and 36K) following bacterial inoculation. Resistance genes (SAP6, BAC6, BC420 and R7313 for Xap; SR13, ST8, SH11 and SB10 for Psp) were screened using SCAR markers under greenhouse conditions. Four-week-old bean seedlings were inoculated with Xap and Psp isolates and leaf samples (1 g) were collected at 0, 12, 24, 48 and 72 hours post-inoculation for enzyme assays. 
 
Result: Under greenhouse conditions, the lowest disease incidence and severity for CBB and HB were observed in XAN159, Vax1, Ozmen, Noyanbey and 36K (p&le;0.01). The SAP6 and BAC6 resistance genes were present in all cultivars except Alberto and Aras 98, respectively, while the SR13 gene was absent in Noyanbey and Aras 98. POX activity increased by 198.40% in the 36K cultivar at 36 hours post-inoculation, whereas CAT activity reached its peak (0.4087 U/g FW) in the same cultivar at 72 hours after Psp inoculation (p&le;0.01). The enhanced activities of antioxidant enzymes, along with the presence of specific resistance genes, appear to play a critical role in the defense mechanisms of resistant and susceptible bean genotypes against bacterial infection.

Screening of Resistance Genes and Some Reactive Oxygen Specific Enzymes against Xanthomonas axonopodis Pv. Phaseoli and Pseudomonas savastanoi Pv. Phaseolicola in Bean Varieties

Background: Common bacterial blight (CBB), caused by Xanthomonas axonopodis pv. phaseoli (Xap) significantly impacts common bean production worldwide. Timely identification and characterization of Xap are critical for disease management and breeding for resistance. 
 
Methods: The pathogen was isolated from symptomatic leaves, stems and pods of common bean cultivars, followed by morphological, physiological, biochemical and molecular characterization. Pathogenicity and induction of hypersensitivity reactions of the isolates were confirmed on susceptible bean cultivar and tobacco, respectively. 
 
Result: A total of 35 Xap isolates were Gram-negative, oxidase-negative, catalase-positive and tested positive for levan and H2S production, esculin hydrolysis, acid production from carbohydrates and starch hydrolysis and were non-fluorescent on King&rsquo;s B medium. Pathogenicity and hypersensitivity reactions assays on susceptible bean cultivar and tobacco, respectively, confirmed the virulence of the isolates. PCR amplification using Xap-specific primers yielded the expected 730 bp product for all isolates, confirming their identity. Plasmid profiling revealed all isolates carried plasmids of similar size, suggesting limited plasmid size diversity among strains from the same agroecological zone. The combination of classical, biochemical and molecular methods provided a reliable strategy for Xap identification, laying a foundation for further studies on identification of Xap strains.

​​Evaluation of Dry Bean Cultivars in Turkey for Resistance against Common Bacterial Blight Disease

Screening of Resistance Genes and Some Reactive Oxygen Specific Enzymes against Xanthomonas axonopodis Pv. Phaseoli and Pseudomonas savastanoi Pv. Phaseolicola in Bean Varieties

Biochemical and Molecular Characterization of Xanthomonas axonopodis Pv Phaseoli of Common Bean

Evaluation of Dry Bean Cultivars in Turkey for Resistance against Common Bacterial Blight Disease