桃、李和亚洲梨上三种拟茎点霉分离株的致病性及分子特征分析

Uddin W, Stevenson K L, Pardo-Schultheiss R A, Rehner S A

Department of Plant Pathology, University of Georgia, Athens 30602.

Systematic Botany and Mycology Laboratory, USDA-ARS, B011A BARCWEST, Beltsville 20705.

Plant Dis. 1998 Jul;82(7):732-737. doi: 10.1094/PDIS.1998.82.7.732.

Three isolates of Phomopsis, causing shoot blight of peach, shoot tissue necrosis of plum, or bud death of Hosui Asian pear, respectively, were evaluated for their pathogenicity on apple, pear, peach, and plum. Current year's shoots of 1-year-old Stayman Winesap apple, Barlett pear, Babygold-7 peach, and Bruce plum trees were inoculated with each isolate by wounding a bud and applying agar blocks bearing young hyphae. The length of cankers on shoots was measured 10, 17, and 24 days after inoculation. Cankers developed on shoots of all hosts inoculated with the peach isolate and on peach shoots inoculated with plum and Asian pear isolates. No cankers developed on apple, pear, or plum shoots inoculated with plum and Asian pear isolates. In the first experiment, 10 days after inoculation, the length of cankers on apple trees (56.0 mm) inoculated with the peach isolate was not significantly different (P ≥ 0.05) from that on peach (42.8 mm), but was significantly greater than that on plum (25.3 mm) and pear (13.1 mm). The cankers on peach were significantly longer than those on pear, but not on plum. Cankers on all four hosts were significantly different from one another 17 and 24 days after inoculation. There was no significant difference between the length of cankers on peach shoots inoculated with plum and Asian pear isolates, and they were significantly smaller than those inoculated with the peach isolate. None of the control trees developed cankers. The three isolates differed in colony morphology, and appearance of conidiomata, conidiogenous cells, and α-conidia on potato-dextrose agar. None of the isolates produced β-conidia in culture. Multi-locus DNA fingerprint analysis and internal transcribed spacer sequence comparisons revealed similarities between the plum and Asian pear isolates but a significant difference between these two and the peach isolate. The results indicate that the Phomopsis sp. that causes shoot blight of peach has the potential to cause disease on other stone and pome fruits, and peach may also be susceptible to isolates of Phomopsis from different tree fruit hosts.

分别对引起桃梢枯病、李梢组织坏死或丰水梨芽死亡的三种拟茎点霉分离株进行了苹果、梨、桃和李的致病性评估。通过损伤芽并接种带有幼嫩菌丝的琼脂块，将每种分离株接种到1年生斯泰曼·温莎苹果、巴梨、金童7号桃和布鲁斯李树的当年生枝条上。接种后10、17和24天测量枝条上溃疡病斑的长度。接种桃分离株的所有寄主枝条以及接种李和亚洲梨分离株的桃枝条上均出现了溃疡病斑。接种李和亚洲梨分离株的苹果、梨或李枝条上未出现溃疡病斑。在第一个实验中，接种后10天，接种桃分离株的苹果树上溃疡病斑长度（56.0毫米）与桃树上的（42.8毫米）无显著差异（P≥0.05），但显著大于李树（25.3毫米）和梨树（13.1毫米）上的。桃树上的溃疡病斑显著长于梨树上的，但与李树上的无显著差异。接种后17天和24天，所有四种寄主上的溃疡病斑均存在显著差异。接种李和亚洲梨分离株的桃枝条上溃疡病斑长度之间无显著差异，且显著小于接种桃分离株的。对照树均未出现溃疡病斑。这三种分离株在马铃薯葡萄糖琼脂上的菌落形态、分生孢子器、产孢细胞和α-分生孢子的外观存在差异。所有分离株在培养中均未产生β-分生孢子。多位点DNA指纹分析和内转录间隔区序列比较显示，李和亚洲梨分离株之间存在相似性，但这两者与桃分离株之间存在显著差异。结果表明，引起桃梢枯病的拟茎点霉有在其他核果类和仁果类果实上致病的潜力，桃也可能易受来自不同树果寄主的拟茎点霉分离株的侵染。