Jarullah B M S, Subramanian R B, Jummanah M S J
Department Of Biosciences, Sardar Patel University Vallabh Vidyanagar - 388 120, Gujarat, India.
Commun Agric Appl Biol Sci. 2005;70(4):897-903.
A number of phylogenetic studies have been carried out on biocontrol agents having similar biological control activity. However, no work has been carried out to determine the phylogenetic relationship amongst various groups of biological control agents with varied biocontrol properties. Our aim was to derive a phylogenetic relationship between diverse biocontrol agents belonging to the deuteromycetes and determine its correlation with their spore morphology and their biocontrol activity. RAPD was used to assess genomic variability in fungi used as biological control agents which included ten isolates of nematophagous fungi such as Arthrobotrys sp., Duddingtonia sp., Paecilomyces sp. and Verticillium sp., along with two isolates of fungal biocontrol agents such as Trichoderma sp. and two isolates of entomopathogenic fungi including Beauveria sp. A plant pathogenic fungus, Verticillium alboatrum was also included to increase the diversity of Deuteromycetes used. A similarity matrix was created using Jaccard's similarity coefficient & clustering was done using unweighted pair group arithmetic mean method (UPGMA). The final dendogram was created using a combination of two programs, Freetree and TreeExplorer. The phylogenetic tree constructed from the RAPD data showed marked genetic variability among different strains of the same species. The spore morphologies of all these fungi were also studied. The phylogenetic pattern could be correlated with the conidial and conidiophore morphology, a criterion commonly used for the classification of fungi in general and Deuteromycetes in particular. Interestingly, the inferred phylogeny showed no significant grouping based on either their biological control properties or the trapping structures amongst the nematophagous fungi as reported earlier by other workers. The phylogenetic pattern was also similar to the tree obtained by comparing the 18S rRNA sequences from the database. The result clearly indicates that the classical method of classification of these deuteromycete members on the basis of their spore morphology is reliable and could be used for identification of these fungi at species level. The PCR fragment pattern polymorphism exhibited by the various species of a genus and different strains of a species indicates that construction of probes from one or more of these fragments will prove to be useful as a rapid tool for identification of species and strains of nematophagous fungi in future.
已对具有相似生物防治活性的生物防治剂开展了多项系统发育研究。然而，尚未开展任何工作来确定具有不同生物防治特性的各类生物防治剂之间的系统发育关系。我们的目标是推导属于半知菌类的不同生物防治剂之间的系统发育关系，并确定其与孢子形态及其生物防治活性的相关性。随机扩增多态性DNA（RAPD）用于评估用作生物防治剂的真菌的基因组变异性，其中包括10株食线虫真菌分离株，如节丛孢属、隔指孢属、拟青霉属和轮枝菌属，以及2株真菌生物防治剂分离株，如木霉属，还有2株昆虫病原真菌分离株，包括白僵菌属。还纳入了一种植物病原真菌——黑白轮枝菌，以增加所用半知菌类的多样性。使用杰卡德相似系数创建相似性矩阵，并使用非加权配对组算术平均法（UPGMA）进行聚类。最终的树状图是使用两个程序Freetree和TreeExplorer组合创建的。根据RAPD数据构建的系统发育树显示同一物种的不同菌株之间存在显著的遗传变异性。还研究了所有这些真菌的孢子形态。系统发育模式可与分生孢子和分生孢子梗形态相关联，这是一般用于真菌分类尤其是半知菌类分类的一个标准。有趣的是，如其他研究人员先前报道的那样，推断的系统发育并未显示基于其生物防治特性或食线虫真菌中的捕食结构的明显分组。系统发育模式也与通过比较数据库中的18S rRNA序列获得的树相似。结果清楚地表明，基于孢子形态对这些半知菌类成员进行分类的经典方法是可靠的，可用于在物种水平上鉴定这些真菌。一个属的不同物种和一个物种的不同菌株所表现出的PCR片段模式多态性表明，从这些片段中的一个或多个构建探针将被证明是未来快速鉴定食线虫真菌物种和菌株的有用工具。
