Centre for Crop Health, University of Southern Queensland, Toowoomba, Queensland, Australia.
Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia.
Plant Dis. 2017 Aug;101(8):1422-1431. doi: 10.1094/PDIS-01-17-0016-RE. Epub 2017 May 12.
Leifsonia xyli subsp. xyli, causal agent of ratoon stunting disease (RSD) of sugarcane (Saccharum interspecific hybrids), is the most well-known member of the Microbacteriaceae genus Leifsonia. However, the presence of other Leifsonia strains associated with sugarcane has not been reported. A total of 697 Australian and 40 Indonesian sugarcane fields were screened by leaf sheath biopsy (LSB) PCR using primers specific for L. xyli subsp. xyli, in addition to primers designed to amplify DNA from other members of the genus Leifsonia. While L. xyli subsp. xyli was detected in 126 fields, a total of 37 distinct and novel Leifsonia and non-Leifsonia strains were detected in 116 fields. Representatives of these strains were also detected in multiple samples of expressed xylem sap. Sequencing and phylogenetic analyses demonstrated the presence of a broad complex of novel Leifsonia strains, in addition to strains closely related to the recently erected Cnuibacter genus. Attempts to isolate Leifsonia strains were unsuccessful; however, one strain related to Cnuibacter was recovered from expressed xylem sap. Among the genetically diverse lineages discovered, identical genotypes were present in multiple sugarcane varieties growing in disparate regions in different years, strongly suggesting an ongoing association with sugarcane. The epidemiological significance of these strains is unknown, but there is evidence that they can interfere with serological and microscopic RSD diagnostics, and there is the potential that they may represent new and distinct pathologies of sugarcane.
木杆菌属李式亚种，甘蔗丛矮病（RSD）的致病因子，是木杆菌属中最为人熟知的成员。然而，尚未有报道称存在与甘蔗相关的其他李式杆菌菌株。使用针对李式亚种特异性的引物，通过叶鞘活检（LSB）PCR 对来自澳大利亚的 697 个和印度尼西亚的 40 个甘蔗田进行了筛查，此外还设计了用于扩增属内其他李式杆菌菌株 DNA 的引物。虽然在 126 个田块中检测到了李式亚种，但在 116 个田块中总共检测到了 37 种不同的新型李式杆菌和非李式杆菌菌株。这些菌株的代表也在多个表达木质部汁液样本中被检测到。测序和系统发育分析表明，除了与最近成立的 Cnuibacter 属密切相关的菌株外，还存在一个新型李式杆菌菌株的广泛复杂群体。尝试分离李式杆菌菌株并未成功；然而，从表达木质部汁液中回收了一株与 Cnuibacter 相关的菌株。在所发现的遗传多样性谱系中，在不同年份种植在不同地区的多个甘蔗品种中存在相同的基因型，这强烈表明其与甘蔗之间存在持续的关联。这些菌株的流行病学意义尚不清楚，但有证据表明它们可能干扰血清学和显微镜 RSD 诊断，并且它们可能代表了甘蔗的新的、不同的病理学。
