【摘要】 【目的】明确引起两杂柑品种(‘天草’和‘费尔切尔德’)严重落叶、枯梢现象的病原菌。【方法】在重庆柑橘园区采集典型染病杂柑叶片和果实,对染病组织进行分离,得到10株代表菌株,随机选取菌株FL-1和TCL-1进行形态学特征观察和致病性验证。采用多聚半乳糖醛酸酶基因(endoPG)片段引物PG2和PG3进行分子鉴定。【结果】鉴定菌株在PDA培养基上菌落颜色呈橄榄色,产生黑色色素浸入培养基内,褐色分生孢子,多呈链状分隔。将测序结果提交GenRank通过与NCBI已登录的柑橘褐斑病菌endoPG序列比对发现,相似率高达99%。【结论】通过培养性状、形态学特征研究结合分子鉴定技术表明2种杂柑上发生的病害病原菌为链格孢菌[Alternaria alternata(Fr.)Keissler],与重庆万州红橘爆发的病害同系柑橘褐斑病。更多还原

【Abstract】 【Objective】The objective of the study was to identify the pathogen of a severe defoliation and dieback disease broken out in ‘Amakusa’ and ‘Fairchild’ tangerine hybrid varieties. 【Method】 In 2012, the infected leaf and fruit samples were collected from the citrus orchard in Chongqing. Ten typical strains were isolated from the samples by tissue isolation techniques. Two strains(FL-1 and TCL-1) randomly selected was studied with the characteristics of morphology, pathogenicity and sequence analysis of the endoPG region with the primers PG2 and PG3. 【Result】 The results showed that the pathogen on the medium of PDA formed olive-green colonies,producing melaninin filtrated into the medium and brown septa te spores. A 463 bp fragment was amplified by PCR method. Sequence alignment of sequences of the tested isolates showed 99% similarities with the deposited sequences from NCBI. 【Conclusion】Based on the culture, morphological characteristics and sequence analysis, it was suggested that the pathogen was Alternaria alternata(Fr.) Keissler, which is consistent with the citrus brown spot outbreaking at Wanzhou, Chongqing.更多还原