Phytopathology. 2001 Nov;91(11):1098-108. doi: 10.1094/PHYTO.2001.91.11.1098.
ABSTRACT Eight strains of Metschnikowia pulcherrima isolated over a 4-year period from an unmanaged orchard and selected for their biocontrol activity against blue mold (caused by Penicillium expansum) of apples were characterized phenotypically, genetically, and for their biocontrol potential against blue mold on apples. All strains grew well and only differed slightly in their growth in nutrient yeast dextrose broth medium at 1 degrees C after 216 h, but large differences occurred at 0 degrees C, with strain T5-A2 outgrowing other strains by more than 25% transmittance after 360 h. This strain was also one of the most resistant to diphenylamine (DPA), a postharvest antioxidant treatment. All strains required biotin for growth in minimum salt (MS) medium, although strain ST2-A10 grew slightly in MS medium containing riboflavin or folic acid, as did ST3-E1 in MS medium without vitamins. None of the strains produced killer toxins against an indicator strain of Saccharomyces cerevisiae. Analysis of Biolog data from YT plates for all eight strains using the MLCLUST program resulted in separation of the strains into one major cluster containing four strains and four scattered strains from which strain ST1-D10 was the most distant from all other strains. This was particularly apparent in 3-D and principle component analysis. Genetic differentiation of the eight strains using maximum parsimony analysis of nucleotide sequences from domain D1/D2 of nuclear large subunit (26S) ribosomal DNA resulted in detection of two clades. Strain ST1-D10 grouped with the type strain of M. pulcherrima but the remaining seven strains grouped separately, which might possibly represent a new species. All strains significantly reduced blue mold on mature Golden Delicious apples during 1 month of storage at 1 degrees C followed by 7 days at room temperature, but strains T5-A2 and T4-A2 were distinctly more effective under these conditions. Strain T5-A2 also was the most effective in tests on harvest mature apples treated with the lowest concentration of the antagonist and stored for 3 months at 0.5 degrees C. Populations of all eight strains increased in apple wounds by approximately 2 log units after 1 month at 1 degrees C followed by 5 days at 24 degrees C. Our results indicate that M. pulcherrima is an excellent candidate for biological control of postharvest diseases of pome fruit. The variation in phenotypic, genetic, and biocontrol characteristics among strains of M. pulcherrima isolated from the same orchard should make it possible to select antagonists with characteristics that are most desirable for postharvest application.
摘要 从一个未管理的果园中分离出的八株长梗木霉，经过 4 年的时间，因其对苹果青霉病（由扩展青霉引起）的生物防治活性而被选中，这些菌株在表型、遗传和对苹果青霉病的生物防治潜力方面都得到了表征。所有菌株的生长情况都很好，只是在 1 摄氏度的营养酵母葡萄糖肉汤培养基中经过 216 小时后生长情况略有不同，但在 0 摄氏度时差异较大，菌株 T5-A2 在 360 小时后透光率超过其他菌株 25%。该菌株对二苯胺（DPA）也有很强的抵抗力，DPA 是一种采后抗氧化处理剂。所有菌株在最低盐（MS）培养基中生长都需要生物素，尽管 ST2-A10 菌株在含有核黄素或叶酸的 MS 培养基中略有生长，ST3-E1 菌株在不含维生素的 MS 培养基中也能生长。没有一株菌株对酿酒酵母的指示菌株产生杀伤毒素。使用 MLCLUST 程序对 YT 平板上的所有 8 株菌株的 Biolog 数据进行分析，结果将菌株分为一个主要聚类，包含 4 株菌株和 4 株分散的菌株，其中 ST1-D10 与所有其他菌株的距离最远。这在 3-D 和主成分分析中尤其明显。利用核大亚基（26S）核糖体 DNA 域 D1/D2 核苷酸序列的最大简约分析对 8 株菌株进行遗传分化，结果检测到两个分支。ST1-D10 菌株与长梗木霉的模式菌株聚在一起，但其余 7 株菌株单独聚在一起，这可能代表一个新的种。在 1 摄氏度下储存 1 个月后再在室温下储存 7 天的过程中，所有菌株都显著减少了成熟金冠苹果上的青霉病，但在这些条件下，T5-A2 和 T4-A2 菌株的效果更为明显。T5-A2 菌株在对用最低浓度拮抗剂处理的收获成熟苹果进行的试验中也最有效，在 0.5 摄氏度下储存 3 个月。所有 8 株菌株在 1 摄氏度下培养 1 个月后，在苹果伤口中的种群数量增加了大约 2 个对数单位，然后在 24 摄氏度下培养 5 天。我们的研究结果表明，长梗木霉是防治苹果采后病害的优秀候选生物防治剂。从同一果园中分离出的长梗木霉菌株在表型、遗传和生物防治特性方面的差异，应该可以选择出最适合采后应用的具有理想特性的拮抗菌株。
