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Genome sequence of the common bean rust pathogen suggests coevolution with its common bean host

Marcial Pastor-Corrales: Soybean Genomics & Improvement Lab, BARC-West, ARS-USDA

<div>Achievement of durable resistance to <em>Uromyces appendiculatus</em>, the causal agent of the common bean rust disease, is difficult due to the extensive virulence of this pathogen. Yet this diversity segregates into two distinct groups that correspond to the Mesoamerican and Andean gene pools of common bean, suggesting that <em>U. appendiculatus</em> has coevolved with its host. To find additional evidence for coevolution, we are using our sequenced data of the genomes of an Andean race (5-0) and a Mesoamerican race (31-1) of <em>U. appendiculatus</em>. De novo assemblies resulted in genomes of 587.6 Mb and 546.7 Mb for races 5-0 and 31-1, respectively. These assemblies contained a high number of contigs, suggesting a complex and highly repetitive genome that is larger (>500Mb) than most of the reported genomes of fungal plant pathogens. Over 110,000 simple sequenced repeats (SSRs) were also identified in each genome assembly. Sixteen SSRs markers were designed and tested on a world collection of 46 Mesoamerican and Andean races of <em>U. appendiculatus</em> maintained at Beltsville. A neighbor-joining analysis separated these races into two major groups that also corresponded to the Andean and Mesoamerican gene pools of common bean. These results suggest coevolution between <em>U. appendiculatus</em> and its common bean host and are crucial to the development of strategies that could result in durable host resistance to the hyper virulent bean rust pathogen.</div>