Hu Meng-Jun, Grabke Anja, Dowling Madeline E, Holstein Helen J, Schnabel Guido
School of Agricultural, Forest & Environmental Sciences, Clemson University, Clemson, SC 29634.
Plant Dis. 2015 Jun;99(6):806-814. doi: 10.1094/PDIS-10-14-1077-RE. Epub 2015 May 15.
Anthracnose fruit rot was observed in some late-season peach cultivars in South Carolina in the 2012 and 2013 production seasons as well as increased anthracnose leaf spot of blueberry in a commercial operation of the same state in 2012. Single-spore isolates of Colletotrichum siamense were either sensitive or resistant to both thiophanate-methyl and azoxystrobin with the concentration of the fungicide at which fungal development is inhibited by 50% of ≥100 μg/ml. Resistant isolates revealed the E198A mutation in β-tubulin and the G143A mutation in cytochrome b. Nucleotide sequence analysis of the complete CYTB gene from genomic DNA of C. siamense isolates revealed an intronless genotype (CsI) and a genotype revealing two introns (CsII) at amino acid positions 131 and 164. Resistance to thiophanate-methyl or azoxystrobin was not found in isolates of C. fructicola collected from peach fruit. The CYTB gene of isolates of this species was of the CfII genotype or revealed a unique CfIIa genotype. Phylogenetic analysis of C. siamense isolates from different locations and different crops showed that the resistant isolates were genetically closer to each other than to sensitive isolates, suggesting that field resistance to thiophanate-methyl and azoxystrobin fungicides is derived from a common ancestor.
2012年和2013年生产季期间，在南卡罗来纳州的一些晚熟桃品种上观察到炭疽果腐病，2012年在该州的一个商业种植园中，蓝莓的炭疽叶斑病也有所增加。暹罗炭疽菌的单孢分离株对甲基硫菌灵和嘧菌酯均表现出敏感或抗性，抑制真菌生长50%的杀菌剂浓度≥100μg/ml。抗性分离株在β-微管蛋白中显示E198A突变，在细胞色素b中显示G143A突变。对暹罗炭疽菌分离株基因组DNA的完整CYTB基因进行核苷酸序列分析，发现一种无内含子基因型（CsI）和一种在氨基酸位置131和164处显示两个内含子的基因型（CsII）。从桃果实上分离得到的胶孢炭疽菌分离株对甲基硫菌灵或嘧菌酯未表现出抗性。该物种分离株的CYTB基因属于CfII基因型或显示出独特的CfIIa基因型。对来自不同地点和不同作物的暹罗炭疽菌分离株进行系统发育分析表明，抗性分离株之间的亲缘关系比与敏感分离株之间的亲缘关系更近，这表明对甲基硫菌灵和嘧菌酯杀菌剂的田间抗性源自一个共同祖先。
