A Patchwork of Streptomyces Species Isolated from Potato Common Scab Lesions in North America

Abstract

To determine distribution and prevalence of Streptomyces species associated with common scab in North America, more than 1,400 isolates were made from scabby potato tubers. Samples were obtained from locations across the continent, and from multiple sites in close geographic proximity. Most potentially pathogenic isolates belonged to four species previously associated with common scab, S. scabies, S. europaeiscabiei, S. stelliscabiei, and S. sp. IdahoX. Additionally, small numbers of potentially pathogenic isolates were identified as S. acidiscabies, S. turgidiscabies and six additional ribotypes. S. europaeiscabiei was most common in the west and S. scabies predominated in the middle and eastern Midwest. Beyond this geographic trend, species distribution was patchy. A single species often predominated in a field while neighboring fields had different species. Local and regional variation was seen when isolates were genotyped for repetitive sequence element patterns, reflecting the conserved or core genome, and genes characteristic of the Streptomyces pathogenicity island, reflecting flexible components of the Streptomyces genome. This is the largest survey to date of the distribution of common scab-causing species, and will be a resource for population biology studies and for tracing the evolutionary history and spread of common scabassociated Streptomyces.Resumen Para determinar la distribución y prevalencia de especies de Streptomyces asociadas con la sarna común en Norteamérica, se hicieron más de 1,400 aislamientos de tubérculos de papa con sarna. Las muestras fueron obtenidas de localidades de todo el continente y de múltiples lugares geográficamente próximos. Los aislamientos potencialmente más patogénicos fueron de cuatro especies previamente asociadas con sarna común, S. scabies, S. europaeiscabiei, S. stellicabiei y S. sp. IdahoX. Adicionalmente, un número pequeño de aislamientos potencialmente patogénicos fueron identificados como S. acidiscabies, S. turgidiscabies y seis ribotipos adicionales. S. europaeiscabiei fue el más común en el oeste y S. scabies predominó en el centro y este del Medio Oeste. Más allá de esta tendencia geográfica, la distribución de especies fue en parches. Una sola especie a menudo predominó en un campo mientras en los campos vecinos se encontraron diferentes especies. Se vieron variaciones locales y regionales cuando a los aislamientos se les determinó el genotipo para patrones de elementos con secuencias repetitivas que reflejan el genoma conservado o central, y genes característicos de la isla de patogenicidad de Streptomyces, reflejando componentes flexibles del genoma de Streptomyces. Este es la pesquisa más extensa a la fecha sobre la distribución de las especies que causan sarna común, y será un recurso para estudios de biología poblacional y para determinar la historia evolutiva y diseminación de Streptomyces asociado a la sarna común.Keywords Streptomyces scabies . Population genetics . Pathogenicity island Abbreviations CSCommon scab PAI Pathogenicity islan...

Streptomyces species associated with common scab lesions of potatoes in South Africa

“…Most studies base pathogenicity determination of isolates on the presence of txtAB and only conduct pathogenicity pot trials tests on selected isolates (Wanner 2009;Leiminger et al 2012;Dees et al 2013), although Park et al (2003) reported two potato scab-causing isolates from Korea that did not produce thaxtomin. Leiminger et al (2012) and Wanner (2009) also isolated pathogenic but txtAB-negative S. acidiscabies, S. stelliscabiei and S. bottropensis from Germany and North America respectively.…”

“…The interactions between the Streptomyces species, environment and host are complex and result in unpredictable disease incidences, severity and symptomatology between regions and years, making this disease difficult to understand (Wanner 2009). Common scab is not caused by a single species, but rather a species complex within the Streptomyces genus (Loria et al 1997;Wanner 2009).…”

“…Common scab is not caused by a single species, but rather a species complex within the Streptomyces genus (Loria et al 1997;Wanner 2009). Reports of various scab-causing species found within the same field and within the same lesion have led to investigations on species relatedness to specific symptoms and on the sensitivity of species to different environmental conditions (Lindholm et al 1997;Bouchek-Meciche et al 2000;Krištůfek et al 2000;Aittamaa et al 2008;Wiechel and Crump 2010;Khodakaramian and Khodakaramian 2012;Tashiro et al 2012).…”

“…These are not the only scab-causing species and reports of other species are geographically distinct. S. scabiei is found worldwide but is not common in Europe; while S. europaeiscabiei is more often found in Europe, Korea and North America; and S. turgidiscabies is frequently found in Japan and Finland (Lehtonen et al 2004;Wanner 2009;. A multitude of other, poorly described Streptomyces spp.…”

“…is said to be transferred through horizontal gene transfer of pathogenicity and virulence genes (such as txtAB, tomA and nec1) located on a PAI, and there has been an increasing abundance of pathogenic Streptomyces species identified over time (Kers et al 2005;Loria et al 2006;Wanner 2009;Dees et al 2013). For instance S. scabiei and S. europaeiscabiei grow at pH above five (Linholm et al 1997), however, in Japan isolates such as S. acidiscabies that grow at pH 4 are said to cause acid scab (Tashiro et al 2012).…”