Xanthomonas translucens pv. undulosa Identified on Common Weedy Grasses in Naturally Infected Wheat Fields in Minnesota

Abstract

Bacterial leaf streak (BLS) of wheat, caused by Xanthomonas translucens pv. undulosa, has been a notable disease in Minnesota wheat fields over the past decade. Potential sources of the pathogen include infested seed and crop debris. Perennial weeds are also considered a possible inoculum source, but no surveys have been conducted to evaluate which X. translucens pathovars are present on weedy grasses that are common in Minnesota wheat fields. Multilocus sequence analysis (MLSA) of four housekeeping genes (rpoD, dnaK, fyuA, and gyrB) was used to identify 77 strains isolated from six weedy grass species, wheat, and barley in and around naturally infected wheat fields in Minnesota. The MLSA phylogeny identified all strains originating from weedy grass species, except smooth brome, as X. translucens pv. undulosa, whereas strains isolated from smooth brome were determined to be X. translucens pv. cerealis. In planta character states corroborated these identifications on a subset of 41 strains, as all strains from weedy grasses caused water-soaking on wheat and barley in greenhouse assays. Multilocus sequence typing (MLST) was used to evaluate genetic diversity and revealed that sequence types of X. translucens pv. undulosa originating from weedy grass hosts are similar to those found on wheat. This study identifies both annual and perennial poaceous weeds common in Minnesota that can harbor X. translucens pv. undulosa and expands our understanding of the diversity of the pathogen population.

Genetic mapping of QTLs for resistance to bacterial leaf streak in hexaploid wheat

“…Boost and Mace are HRSW cultivars developed in the US and Australia, respectively. The BLS resistance in Boost has been reported before, and it was considered the most promising cultivar in terms of BLS resistance among numerous cultivars tested in the United States (Ledman et al 2023). However, despite its recognition as resistance cultivar for some years, no studies have been conducted to investigate the genetics of BLS resistance in Boost.…”

rpfFis not required forX. translucenspv. undulosa pathogenesis

“…It can cause yield losses as great as 40% (Forster and Schaad 1988; Sapkota et al 2020) and in recent decades has increased as a concern, especially in North America (Ledman et al 2023; Tambong et al 2021; Curland et al 2018, 2020; Hangamaisho et al 2024). Xtu is thought to spread by wind, rain and on seeds (Sapkota et al 2020; Ledman et al 2023). It enters leaves via natural openings such as stomata or damage points (Sapkota et al 2020; Heiden et al 2023; Adhikari et al 2012).…”

“…Once it gains entry to a wheat plant, Xtu extensively colonizes the apoplastic spaces of the mesophyll tissue (Heiden et al 2023; Gluck-Thaler et al 2020; Bragard et al 1997; Sapkota et al 2020; Jones et al 1917). Once it reaches a high population, bacterial leaf streak manifests by macroscopic watersoaking symptoms followed by chlorotic and necrotic vein-delimited symptoms which give bacterial leaf streak its name (Ledman et al 2023; Bamberg 1936; Jones et al 1917; Sapkota et al 2020). Once an Xtu population reaches a high level and encounters humid conditions, it oozes back out of stomata in exudates (Bamberg 1936).…”

Detection and differentiation ofXanthomonas translucenspathovarstranslucensandundulosafrom wheat and barley by duplex quantitative PCR

“…The subspecies classification of X. translucens has presented challenges in distinguishing between pathovars. While whole genome sequencing (Langlois et al 2017) and multilocus sequence analysis (Curland et al 2018; Ledman et al 2021; Tambong et al 2021) have been effective in identifying pathovars, they are time-consuming and impractical on plant samples. One loop-mediated isothermal amplification (LAMP) protocol has been developed (Langlois et al 2017) for the specific detection of three X. translucens pathovars, but cannot differentiate between them.…”