AUTHOR=Soler-Garzón Alvaro , McClean Phillip E. , Miklas Phillip N. 

TITLE=Coding Mutations in Vacuolar Protein-Sorting 4 AAA+ ATPase Endosomal Sorting Complexes Required for Transport Protein Homologs Underlie bc-2 and New bc-4 Gene Conferring Resistance to Bean Common Mosaic Virus in Common Bean

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.769247

DOI=10.3389/fpls.2021.769247

ISSN=1664-462X

ABSTRACT=<p><italic>Bean common mosaic virus</italic> (BCMV) is a major disease in common bean (<italic>Phaseolus vulgaris</italic> L.). Host plant resistance is the most effective strategy to minimize crop damage against BCMV and the related <italic>Bean common mosaic necrosis virus</italic> (BCMNV). To facilitate breeding for resistance, we sought to identify candidate genes and develop markers for the <italic>bc-2</italic> gene and the unknown gene with which it interacts. Genome-wide association study (GWAS) of the Durango Diversity Panel (DDP) identified a peak region for <italic>bc-2</italic> on chromosome Pv11. Haplotype mapping narrowed the <italic>bc-2</italic> genomic interval and identified Phvul.011G092700, a vacuolar protein-sorting 4 (Vps4) AAA+ ATPase endosomal sorting complexes required for transport (ESCRT) protein, as the <italic>bc-2</italic> candidate gene. The race Durango Phvul.011G092700 gene model, <italic>bc-2</italic><sup>[UI</sup><sup>111]</sup>, contains a 10-kb deletion, while the race Mesoamerican <italic>bc-2</italic><sup>[Robust]</sup> consists of a single nucleotide polymorphism (SNP) deletion. Each mutation introduces a premature stop codon, and they exhibit the same interaction with the pathogroups (PGs) tested. Phvul.005G125100, another Vps4 AAA+ ATPase ESCRT protein, was identified as the candidate gene for the new recessive <italic>bc-4</italic> gene, and the recessive allele is likely an amino acid substitution in the microtubule interacting and transport (MIT) domain. The two Vps4 AAA+ ATPase ESCRT proteins exhibit high similarity to the <italic>Zym</italic> Cucsa.385040 candidate gene associated with recessive resistance to <italic>Zucchini yellow mosaic virus</italic> in cucumber. <italic>bc-2</italic> alone has no resistance effect but, when combined with <italic>bc-4</italic>, provides resistance to BCMV (except PG-V) but not BCMNV, and, when combined with <italic>bc-u</italic><sup>d</sup>, provides resistance to BCMV (except BCMV PG-VII) and BCMNV. So instead of different resistance alleles (i.e., <italic>bc-2</italic> and <italic>bc-2</italic><sup>2</sup>), there is only <italic>bc-2</italic> with a differential reaction based on whether it is combined with <italic>bc-4</italic> or <italic>bc-u</italic><italic><sup>d</sup></italic>, which are tightly linked in repulsion. The new tools and enhanced understanding of this host-virus pathogen interaction will facilitate breeding common beans for resistance to BCMV and BCMNV.</p>