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Phylogenetic analysis of South American Berberis species and their related rust fungi

Charles Barnes: Instituto Nacional de Investigaciones Agropecuarias

<div>New races of both <em>Puccinia graminis</em> and <em>P. striiformis</em> are frequently reported throughout the world. Sexual recombination on a susceptible <em>Berberis</em> species host may have produced some of these new reported races, or could generate future new races. The two centers of diversity of simple-leaved <em>Berberis</em> were separated in the Cretaceous period into South American and Asian populations. In South America there are two distinct subgroups: the Aequinoctiales and the Euaustrales. In 2016 and 2017, we sampled <em>Berberis</em> and <em>Berberis</em> infected with rust fungi in Ecuador belonging to the Aequinoctiales, and in Argentina, Brazil, Chile, and Uruguay belonging to the Euaustrales. DNA sequences from both the host and rust fungus were used for phylogenetic analysis. Within the Euaustrales <em>Berberis</em>, we collected <em>B. laurina</em>, <em>B. microphylla</em>, <em>B. darwinii</em> , <em>B. linearifolia</em>, <em>B. serrato-dentata</em>, and an unknown <em>Berberis</em> species. Within the Aequinoctiales <em>Berberis</em>, we collected <em>B. hallii</em>, <em>B. lutea</em>, <em>B. pichinchensis</em>, <em>B. grandiflora</em> and two unknown <em>Berberis</em> species. Analyses of the rust ITS sequences suggested that at least 8 distinct species were collected. None were identified as either <em>P. graminis </em>or <em>P. striiformis</em> based on comparisons with available reference DNA data while only one corresponded to a named species, <em>Edythea quitensis</em> (Ecuador). Most rust fungi had one <em>Berberis</em> host. More sampling is needed to rule out South American <em>Berberis</em> as a host for <em>P. graminis</em> or <em>P. striiformis.</em></div>