Collection and characterization of species of Berberis in Argentina, Brazil, Chile, Ecuador and Uruguay.

South America is one of two centres of diversity for the genus Berberis. As the alternate host for both Puccinia graminis Pers.:Pers. and Puccinia striiformis Westend., Berberis spp. are important in increasing the virulence diversity of races of these rust fungi. However, little is known about the susceptibility of South American Berberis to these cereal rust species. To investigate the role of Berberis in cereal rust diversity, we surveyed Argentina, Brazil, Chile, Ecuador and Uruguay in 2016 for Berberis spp. and aecial infection. While no aecial infection was found in Uruguay, rust aecia on Berberis were found in all other countries. Based on sequence analysis, diversity of Berberis forms two distinct phylogenetic groups, with Berberis from Argentina and Brazil differing from those in Ecuador. Analyses of Berberis samples from Chile and Uruguay are in progress, and we hypothesize that they will likely be related to countries from the Southern Cone. Preliminary analyses of rust aecial samples also indicate distinct grouping by region. However this may be an artifact of the small sample size. As this study continues over the next 2 years we may find some rust fungal species that are more widely dispersed and with wider host ranges.