Ferrada Enrique E, Latorre Bernardo A, Zoffoli Juan P, Castillo Antonio
First, second, and third authors: Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Santiago, Chile; and fourth author: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Alameda 3363, Santiago.
Phytopathology. 2016 Feb;106(2):155-65. doi: 10.1094/PHYTO-06-15-0143-R. Epub 2016 Jan 5.
Blossom blight is a destructive disease of plums (Prunus salicina) when humid and temperate weather conditions occur in Chile. Disease incidence ranging from 4 to 53% has been observed. Symptoms include light brown petal necrosis, starting as light brown mottles or V-shaped necrosis at the margins of the petals, progressing to the stamen and pistils. In this study, the etiology of blossom blight of plums was determined. High- and low-sporulating isolates of Botrytis were obtained consistently from blighted blossoms and apparently healthy flowers of plums. Based on colony morphology, conidial production and molecular phylogenetic analysis, these high- and low-sporulating isolates were identified as B. cinerea and B. prunorum sp. nov., respectively. Phylogenetic analysis of the genes glyceraldehyde 3-phosphate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60), and DNA-dependent RNA polymerase subunit II (RPB2) grouped B. prunorum isolates in a single cluster, distantly from B. cinerea and other Botrytis species. The phylogenetic analysis of necrosis and ethylene-inducing protein (NEP1 and NEP2) genes corroborated these results. Analysis of the internal transcribed spacer region and large-subunit (26S) ribosomal DNA and detection of Boty and Flipper transposable elements, were not useful to differentiate between these Botrytis species. Both species were pathogenic on plum flowers and the fruit of plums, apples, and kiwifruits. However, B. prunorum was less virulent than B. cinerea. These pathogens were re-isolated from inoculated and diseased tissues; thus, Koch's postulates were fulfilled, confirming its role in blossom blight of plums. B. cinerea was predominant, suggesting that B. prunorum may play a secondary role in the epidemiology of blossom blight in plums in Chile. This study clearly demonstrated that the etiology of blossom blight of plums is caused by B. cinerea and B. prunorum, which constitute a species complex living in sympatry on plums and possibly on other stone fruit trees.
在智利，当出现潮湿和温和的天气条件时，花腐病是李子（Prunus salicina）的一种毁灭性病害。已观察到病害发生率在4%至53%之间。症状包括浅棕色花瓣坏死，起初为浅棕色斑点或花瓣边缘的V形坏死，随后发展到雄蕊和雌蕊。在本研究中，确定了李子花腐病的病因。从李子的病花和看似健康的花朵中持续获得了产孢量高和产孢量低的葡萄孢菌分离株。基于菌落形态、分生孢子产生和分子系统发育分析，这些产孢量高和产孢量低的分离株分别被鉴定为灰葡萄孢菌和新种李葡萄孢菌。对甘油醛-3-磷酸脱氢酶（G3PDH）、热休克蛋白60（HSP60）和DNA依赖性RNA聚合酶亚基II（RPB2）基因的系统发育分析将李葡萄孢菌分离株归为一个单独的聚类，与灰葡萄孢菌和其他葡萄孢菌物种相距较远。对坏死和乙烯诱导蛋白（NEP1和NEP2）基因的系统发育分析证实了这些结果。对内部转录间隔区和大亚基（26S）核糖体DNA的分析以及对Boty和Flipper转座元件的检测，对于区分这些葡萄孢菌物种并无帮助。这两个物种对李花以及李子、苹果和猕猴桃的果实均具有致病性。然而，李葡萄孢菌的毒力低于灰葡萄孢菌。这些病原体从接种和患病组织中再次分离得到；因此，科赫法则得到满足，证实了它们在李子花腐病中的作用。灰葡萄孢菌占主导地位，这表明李葡萄孢菌可能在智利李子花腐病的流行病学中起次要作用。本研究清楚地表明，李子花腐病的病因是由灰葡萄孢菌和李葡萄孢菌引起的，它们构成了一个共生在李子以及可能在其他核果树上的物种复合体。
