PDF(Pubmed)
Abstract：
Chayote (Sechium edule) is a crop of great economic and pharmaceutical importance in Mexico. Chayote is affected by Phytophthora capsici, which causes plant wilt and fruit rot. Three isolates of P. capsici (A1-C, A2-H, and A3-O) were obtained from three producing areas in Veracruz, Mexico. Morphometric characteristics of sporangia and the colony pattern on three different media were described. They were molecularly identified by amplification of the internal transcribed spacer region (ITS) and the partial sequence of cytochrome c oxidase subunit 1 (COI), sequences that were phylogenetically analyzed. The mating type, pathogenicity in S. edule fruits, and sensitivity to metalaxyl were determined. Isolate A1-C presented the largest sporangium; all sporangia were papillated, with different morphologies and pedicel lengths. All isolates showed different colony patterns: chrysanthemum (A1-C), stellate (A2-H), and petaloid (A3-O). The topology of the phylogenetic tree was similar for the ITS region and COI gene, the sequences of the three isolates clustered with sequences of the genus Phytophthora classified in group 2b, corroborating their identity as P. capsici. The mating type of isolates A1-C and A3-O was A2 and of isolate A2-H was A1. The pathogenicity test indicated that isolate A1-C was the most virulent and with intermediate sensitivity to metalaxyl. This work suggests that P. capsici isolates from various production areas in Mexico may exhibit morphological and virulence variability.
摘要：
Chayote（Sechiumedule）是墨西哥具有重要经济和药学意义的作物。Chayote受辣椒疫霉的影响，导致植物枯萎和水果腐烂。三种分离株（A1-C，A2-H,和A3-O）是从韦拉克鲁斯的三个产区获得的，墨西哥。描述了孢子囊的形态特征和在三种不同培养基上的菌落模式。通过扩增内部转录间隔区（ITS）和细胞色素c氧化酶亚基1（COI）的部分序列进行分子鉴定，经过系统发育分析的序列。交配类型，沙丘果实的致病性，并测定了对甲霜灵的敏感性。分离物A1-C表现为最大的孢子囊；所有孢子囊均呈乳头状，具有不同的形态和花梗长度。所有分离株显示不同的菌落模式：菊花（A1-C），星状（A2-H），和花瓣状（A3-O）。ITS区域和COI基因的系统发育树拓扑结构相似，三个分离株的序列与分类为2b组的疫霉属的序列成簇，证实了他们作为P.capsici的身份.分离株A1-C和A3-O的交配类型为A2，分离株A2-H的交配类型为A1。致病性试验表明，分离株A1-C的毒力最强，对甲霜灵具有中等敏感性。这项工作表明，来自墨西哥各个生产区的辣椒分离株可能表现出形态和毒力变异性。
