Alvarez Elizabeth, Mejía Juan F, Llano Germán A, Loke John B, Calari Alberto, Duduk Bojan, Bertaccini Assunta
Plant Pathology Program, Tropical Fruit Project, International Center for Tropical Agriculture (CIAT), Cali, Valle del Cauca, Colombia.
DiSTA, Patologia Vegetale, Alma Mater Studiorum, University of Bologna, Italy.
Plant Dis. 2009 Nov;93(11):1139-1145. doi: 10.1094/PDIS-93-11-1139.
Cassava frogskin disease (CFSD) is an economically important root disease of cassava (Manihot esculenta) in Colombia and other South American countries, including Brazil, Venezuela, Peru, Costa Rica, and Panama. The roots of severely affected plants are thin, making them unsuitable for consumption. In Colombia, phytoplasma infections were confirmed in 35 of 39 genotypes exhibiting mild or severe CFSD symptoms either by direct or nested polymerase chain reaction (PCR) assays employing ribosomal (r)RNA operon primer pairs. The CFSD-associated phytoplasmas were identified as group 16SrIII strains by restriction fragment length polymorphism (RFLP) and sequence analyses of amplified rDNA products, and results were corroborated by PCRs employing group 16SrIII-specific rRNA gene or ribosomal protein (rp) gene primers. Collectively, RFLP analyses indicated that CFSD strains differed from all phytoplasmas described previously in group 16SrIII and, on this basis, the strains were tentatively assigned to new ribosomal and ribosomal protein subgroups 16SrIII-L and rpIII-H, respectively. This is the first molecular identification of a phytoplasma associated with CFSD in cassava in Colombia.
木薯蛙皮病（CFSD）是哥伦比亚以及包括巴西、委内瑞拉、秘鲁、哥斯达黎加和巴拿马在内的其他南美国家木薯（Manihot esculenta）一种具有重要经济影响的根部病害。严重受影响植株的根部细小，不适于食用。在哥伦比亚，通过使用核糖体（r）RNA操纵子引物对的直接或巢式聚合酶链反应（PCR）检测，在39个表现出轻度或重度CFSD症状的基因型中，有35个基因型被证实感染了植原体。通过对扩增的rDNA产物进行限制性片段长度多态性（RFLP）分析和序列分析，与CFSD相关的植原体被鉴定为16SrIII组菌株，并且使用16SrIII组特异性rRNA基因或核糖体蛋白（rp）基因引物进行的PCR证实了结果。总体而言，RFLP分析表明，CFSD菌株与先前描述的16SrIII组中的所有植原体不同，基于此，这些菌株分别被初步归入新的核糖体和核糖体蛋白亚组16SrIII-L和rpIII-H。这是哥伦比亚首次对与木薯CFSD相关的植原体进行分子鉴定。
