Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695.
Plant Dis. 2021 Jul;105(7):1960-1966. doi: 10.1094/PDIS-09-20-1929-RE. Epub 2021 Aug 4.
Black shank is a devastating disease of tobacco caused by . Host resistance has been an integral part of black shank management but after the loss of single-gene resistance following its widespread deployment in the 1990s, growers have relied on varieties with varying levels of partial resistance. Partial resistance is effective in suppressing disease, but continued exposure can result in an increase in pathogen aggressiveness that threatens durability of the resistance to . Aggressiveness components in were characterized following adaptation on two sources of partial resistance, Fla 301 and the genomic region from . An aggressive isolate of the two major races of , race 0 and race 1, was adapted for either one/two or five/six generations on the two resistance sources, giving four sets of isolates based on race, number of generations of adaptation, and source of resistance. Across the four sets of isolates, adapted isolates infected higher proportions of tobacco root tips, produced more sporangia per infected root tip, and caused larger lesions than their respective nonadapted isolates of the same race and from the same resistance source. Adapted isolates also produced more aggressive zoospore progeny than the nonadapted isolates. Adaptation to partial resistance involves multiple aggressiveness components and results in the increased aggressiveness observed for . These results improve our knowledge on the nature of adaptation to partial resistance in tobacco and indicate that different resistance sources are likely to select for similar aggressiveness components in the pathogen.
黑胫病是烟草的一种毁灭性疾病，由 引起。寄主抗性一直是黑胫病管理的一个组成部分，但在 20 世纪 90 年代广泛部署的单基因抗性丧失后，种植者依赖于具有不同程度部分抗性的品种。部分抗性在抑制疾病方面是有效的，但持续暴露可能导致病原体侵袭性增加，从而威胁到对 的抗性的耐久性。在两种部分抗性来源 Fla 301 和 基因组区域上适应后，对 中的侵袭性成分进行了特征描述。两种主要的 ，即 0 号和 1 号菌系，在这两个抗性来源上适应了一个/两个或五个/六个世代，产生了基于菌系、适应世代数和抗性来源的四组分离物。在这四组分离物中，适应的分离物感染了更高比例的烟草根尖，每个受感染的根尖产生更多的游动孢子，并导致比其各自的相同菌系和来自相同抗性源的非适应分离物更大的病变。适应的分离物也产生了比非适应的分离物更具侵袭性的游动孢子后代。对部分抗性的适应涉及多个侵袭性成分，并导致观察到的 增加的侵袭性。这些结果提高了我们对烟草中 对部分抗性适应的性质的认识，并表明不同的抗性来源可能会在病原体中选择类似的侵袭性成分。
