A Comprehensive Review of the Major Genes Conditioning Resistance to Anthracnose in Common Bean

Abstract

<jats:p>Resistance to anthracnose in common bean is conditioned primarily by nine major independent genes, <jats:italic>Co-1</jats:italic> to <jats:italic>Co-10</jats:italic> as the <jats:italic>Co-3/Co-9</jats:italic> genes are allelic. With the exception of the recessive <jats:italic>co-8</jats:italic> gene, all other nine are dominant genes and multiple alleles exist at the <jats:italic>Co-1, Co-3</jats:italic> and <jats:italic>Co-4</jats:italic> loci. A reverse of dominance at the <jats:italic>Co-1</jats:italic> locus suggests that an order of dominance exists among individual alleles at this locus. The nine resistance genes <jats:italic>Co-2</jats:italic> to <jats:italic>Co-10</jats:italic> are Middle American in origin and <jats:italic>Co-1</jats:italic> is the only locus from the Andean gene pool. Seven resistance loci have been mapped to the integrated bean linkage map and <jats:italic>Co-1</jats:italic> resides on linkage group B1; <jats:italic>Co-2</jats:italic> on B11, <jats:italic>Co-3</jats:italic> on B4; <jats:italic>Co-4</jats:italic> on B8; <jats:italic>Co-6</jats:italic> on B7; and <jats:italic>Co-9</jats:italic> and <jats:italic>Co-10</jats:italic> are located on B4 but do not appear to be linked. Three <jats:italic>Co</jats:italic>-genes map to linkage groups B1, B4 and B11 where clusters with genes for rust resistance are located. In addition, there is co-localization with major resistance genes and QTL that condition partial resistance to anthracnose. Other QTL for resistance may provide putative map locations for the major resistance loci still to be mapped. Molecular markers linked to the majority of major <jats:italic>Co</jats:italic>-genes have been reported and these provide the opportunity to enhance disease resistance through marker-assisted selection and gene pyramiding. The 10 <jats:italic>Co</jats:italic>-genes are represented in the anthracnose differential cultivars, but are present as part of a multi-allelic series or in combination with other <jats:italic>Co</jats:italic>-genes, making the characterization of more complex races difficult. Although the <jats:italic>Co</jats:italic>-genes behave as major Mendelian factors, they most likely exist as resistance gene clusters as has been demonstrated on the molecular level at the <jats:italic>Co-2</jats:italic> locus. Since the genes differ in their effectiveness in controlling the highly variable races of the anthracnose pathogen, the authors discuss the value of individual genes and alleles in resistance breeding and suggest the most effective gene pyramids to ensure long-term durable resistance to anthracnose in common bean.</jats:p>

Genetic Characterization of Green Bean (Phaseolus vulgaris L.) Accessions from Turkey with SCAR and SSR Markers

“…Resistance to anthracnose is conditioned by independent genes Co-1 to Co-10. STS marker SE act M cca associated with Co-1 locus conditioning resistance to anthracnose (Kelly and Vallejo 2004) These findings were consistent with Kelly and Vallejo (2004) reporting that three Andean cultivars MDRK, PM, and Kaboon carry different alleles at the Co-1 locus. Such that, in addition to the Co-1 allele at MDRK, Co-1 2 and Co-1 3 alleles are reported in Kaboon and PM and probably Co-1 5 allele in the Mesoamerican origin cultivar Widusa (Kelly and Vallejo 2004).…”

“…STS marker SE act M cca associated with Co-1 locus conditioning resistance to anthracnose (Kelly and Vallejo 2004) These findings were consistent with Kelly and Vallejo (2004) reporting that three Andean cultivars MDRK, PM, and Kaboon carry different alleles at the Co-1 locus. Such that, in addition to the Co-1 allele at MDRK, Co-1 2 and Co-1 3 alleles are reported in Kaboon and PM and probably Co-1 5 allele in the Mesoamerican origin cultivar Widusa (Kelly and Vallejo 2004). MDRK of Andean origin was reported to carry 80 bp resistance allele of Co-1 gene designated as the first gene determined for resistance to anthracnose present in Andean origin gene pool (Madakbaş et al 2013).…”

“…SCAR markers Phs related to common bacterial blight, white mold (Sclerotinia sclerotiorum), and phaseolin protein (Miklas 2007); SAP 6 associated with common bacterial blight (Miklas et al 2000); SB 10 with halo blight (Fourie et al 2004); and SBB 14 linked to anthracnose Co-4 gene were used (Awale and Kelly 2001) together with an STS marker SE act M cca associated with common bean anthracnose (Kelly and Vallejo 2004).…”

“…Genetic linkage maps in common bean provided the positioning of QTLs and identified markers tightly linked to the target loci (Blair et al 2003;Miklas et al 2014;Keller et al 2015). Reliable markers for resistance against biotic and abiotic stress factors provided successful application of MAS (marker-assisted selection) in common bean (Fourie et al 2004;Kelly and Vallejo 2004;Miklas et al 2014). …”

Genetic analysis of anthracnose resistance in common bean breeding source germplasm

“…Previous studies have also reported that a few (less than 3) genes influenced resistance to different races of anthracnose in bean germplasm including AB136 (Alzate-Marin et al 1997). Kelly and Vallejo (2004) reported that there are nine major genes (Co-1-Co-10) that are responsible for controlling anthracnose resistance in dry beans. The involvement of a few or major genes in germplasm, which is adapted to Ugandan conditions, suggests that molecular markers linked to these genes could be identified for use in marker-assisted backcrossing to accelerate the breeding process in the future.…”