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Intra- and inter-field diversity of Xanthomonas translucens isolates associated with natural occurrence of bacterial leaf streak in wheat and barley

Rebecca Curland: University of Minnesota

<div>Bacterial leaf streak (BLS) has been a disease of increasing concern over the past decade. Recent studies have shown that both <em>X. translucens</em> pv. <em>undulosa</em> (wheat and barley) and <em>X. translucens</em> pv. <em>translucens</em> (barley) are common in the Northern Great Plains. Phylogenetic analyses of multilocus sequence alignments (MLSA) of isolates from this region substantiated the close relatedness of both pathovars. Multilocus sequence typing (MLST) further determined the existence of multiple sequence types of each pathovar at the national and regional scale. Here we evaluated the intra- and inter-field scale genetic diversity of bacteria causing BLS. Twenty-five leaf samples from two wheat and two barley fields, showing natural infections of BLS, were collected during the growing season of 2015. Bacteria from individual leaves were isolated on Wilbrink’s agar. Colonies characteristic of <em>X. translucens</em> were purified and stored. Pathogenicity and relative virulence of isolates were assayed in wheat and barley seedlings. Phylogenies and sequence types were ascertained from analyses of the concatenated sequences of four housekeeping genes (<em>rpoD</em>, <em>dnaK,</em> <em>fyuA</em> and <em>gyrB</em>). Estimates of genetic diversity within and between fields were measured. Knowledge of the range of virulence and sequence types of <em>X. translucens.</em> pv. <em>undulosa</em> and <em>X. translucens</em> pv. <em>translucens</em> within prominent areas of wheat and barley production can inform breeding strategies for BLS disease resistance.</div>