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Anthracnose, caused by the fungus Colletotrichum lindemuthianum, poses a significant and widespread threat to the common bean crop. The use of plant genetic resistance has proven to be the most effective strategy for managing anthracnose disease. The Amendoim Cavalo (AC) Andean cultivar has resistance against multiple races of C. lindemuthianum, which is conferred by the Co-AC gene. Fine mapping of this resistance gene to common bean chromosome Pv01 enabled the identification of Phvul.001G244300, Phvul.001G244400, and Phvul.001G244500 candidate genes for further validation. In this study, the relative expression of Co-AC candidate genes was assessed, as well as other putative genes in the vicinity of this locus and known resistance genes, in the AC cultivar following inoculation with the race 73 of C. lindemuthianum. Gene expression analysis revealed significantly higher expression levels of Phvul.001G244500. Notably, Phvul.001G244500 encodes a putative Basic Helix–Loop–Helix transcription factor, suggesting its involvement in the regulation of defense responses. Furthermore, a significant modulation of the expression of defense-related genes PR1a, PR1b, and PR2 was observed in a time-course experiment. These findings contribute to the development of improved strategies for breeding anthracnose-resistant common bean cultivars, thereby mitigating the impact of this pathogen on crop yields and ensuring sustainable bean production. [ABSTRACT FROM AUTHOR]

Anthracnose (ANT) and angular leaf spot (ALS) are significant diseases in common bean, leading to considerable yield losses under specific environmental conditions. The California Dark Red Kidney (CDRK) bean cultivar is known for its resistance to multiple races of both pathogens. Previous studies have identified the CoPv01CDRK/PhgPv01CDRK resistance loci on chromosome Pv01. Here, we evaluated the expression levels of ten candidate genes near the CoPv01CDRK/PhgPv01CDRK loci and plant defense genes using quantitative real-time PCR in CDRK cultivar inoculated with races 73 of Colletotrichum lindemuthianum and 63-39 of Pseudocercospora griseola. Gene expression analysis revealed that the Phvul.001G246300 gene exhibited the most elevated levels, showing remarkable 7.8-fold and 8.5-fold increases for ANT and ALS, respectively. The Phvul.001G246300 gene encodes an abscisic acid (ABA) receptor with pyrabactin resistance, PYR1-like (PYL) protein, which plays a central role in the crosstalk between ABA and jasmonic acid responses. Interestingly, our results also showed that the other defense genes were initially activated. These findings provide critical insights into the molecular mechanisms underlying plant defense against these diseases and could contribute to the development of more effective disease management strategies in the future. [ABSTRACT FROM AUTHOR]

The presence of multiple resistance genes in common bean and the diverse race spectrum of Colletotrichum lindemuthianum suggests that a broad spectrum of resistance mechanisms needs to be deployed in resistance breeding. However, limited studies on the interaction of anthracnose resistance genes and other plant defense genes exist in common bean. Therefore, we analyzed four candidate genes of Co-1 2 allele at the Co-1 locus and plant defense genes via quantitative real time PCR, to determine the fine-tuned timing and magnitude of expression of the resistance reaction. In the present study, a pair of near isogenic lines (NILs; T9576R and T9576S) that differ for the Co-1 2 resistance allele, was used that upon infection with race 73 of C. lindemuthianum show differential gene expression between the NILs. Our aim was to identify a particular gene that is effective against race 73 among other candidate genes located at the Co-1 locus. Gene expression analysis revealed higher expression levels of the Phvul.001G243800 gene. Expression was nearly 144 fold higher in the resistant NIL, than in the susceptible NIL and could be a possible candidate gene effective against race 73. In addition, we found that initially the other defense genes are activated which suggests that both defense and candidate gene activation is necessary to effect resistance against the anthracnose pathogen of common bean. Image 1 • In the present investigation, expression profile of four plant defense and overlapping candidate genes at Co-1 locus were investigated over a time course. • In the susceptible NIL, the plant defense genes activate late in the necrotrophic phase of pathogen. • Our findings identified the candidate gene (Phvul.001G243800) effective against the race 73 of C lindemuthianum. [ABSTRACT FROM AUTHOR]