A new gene conferring resistance to anthracnose in Andean common bean (Phaseolus vulgaris L.) cultivar ‘Jalo Vermelho’

‘Jalo Vermelho’ is a large seeded Andean landrace of common bean (Phaseolus vulgaris L.) that constitutes an important source of anthracnose resistance, disease caused by Colletotrichum lindemuthianum. This landrace has different resistance spectrum, when compared with cultivars of Andean origin, indicating the presence of an anthracnose‐resistant gene different from Co‐1 locus. This anthracnose resistance was characterized by inheritance and allelism tests were carried out on the following genes: Co‐1, Co‐1², Co‐1³, Co‐1⁵, Co‐2, Co‐3, Co‐4, Co‐5, Co‐6, Co‐7, Co‐9, Co‐10, Co‐11 and Co‐13. Resistance to races 23, 55, 89 and 453 in ‘Jalo Vermelho’ was conditioned by a single dominant gene. Allelism tests in F₂ populations demonstrated that ‘Jalo Vermelho’ carries a dominant gene located at a distinct locus, differing from previously characterized genes. Based on its independence from previously described loci, the authors propose that the ‘Jalo Vermelho’s gene should be named Co‐12. This new gene is a valuable source of resistance to anthracnose which can be transferred to commercial cultivars to enhance the effectiveness of resistance gene pyramiding in bean breeding programmes.