First Report of Ampelomyces quisqualis from Sycamore and Crape Myrtle and Its Potential as a Mycoparasite of Powdery Mildew

Abstract

: During screening fungi as potential biological control agents for plant parasitic fungi, a fungal strain, EML-FAM3, was isolated from powdery mildew leaf lesions caused by Erysiphe platani on sycamore (Platanus occidentalis L.), and another strain, EML-FAMC1, from Erysiphe australiana on crape myrtle (Lagerstroemia indica L.). Based on the morphological characteristics and phylogenetic analysis of the internal transcribed spacers (ITS1 and ITS2) and 5.8S rDNA, the strains were identified as Ampelomyces quisqualis. To our knowledge, this is the first report of new mycohosts, E. platani and E. australiana, of the mycoparasite A. quisqualis on sycamore and crape myrtle plants. The hyperparasite may represent the potential for controlling E. platani and E. australiana epidemics. KEYWORDS : Ampelomyces quisqualis, Hyperparasite, Lagerstroemia indica, Platanus occidentalis, Powdery mildewAmpelomyces spp. are common intracellular mycoparasites of powdery mildews. Pycnidial fungi belonging to the haploid ascomycete genus Ampelomyces are common mycoparasites occurring intracellularly in mycelia of powdery mildews (Erysiphaceae) worldwide [1,2]. The natural co-occurrence of A. quisqualis on various Erysiphaceae species has been reported in different geographic regions [3][4][5][6]. Ampelomyces species have been associated with ca. 65 fungal species of eight genera of the order Erysiphales in different regions globally [2]. In Korea, Ampelomyces has been revealed on 19 species of the genus Erysiphe and occurs on a wide range of plants [7]. To our knowledge, there were no previous published literature records of this species as a mycoparasite of powdery mildew disease on sycamore (Platanus occidentalis L.) and crape myrtle (Lagerstroemia indica L.) hosts.Many researches on A. quisqualis has focused on its potential use as a biocontrol agent against powdery mildews on various crops and woody plants [8,9]. At present, a few Ampelomyces isolates have already been registered as biocontrol agents of powdery mildews, e.g. AQ10 biofungicide is commercially used for the biocontrol of grape powdery mildew [10].Recent research on the phylogenetic analysis based on the internal transcribed spacer (ITS) rDNA sequences revealed that the species could be classified into five different genetic clades, showing that different physiological forms exist within genetically diverse strains of the species [11]. P. occidentalis is widely planted as a street tree distributed in South Korea and is useful in the rehabilitation of various sites with saturated soils. Moreover, it has been used for furniture, veneer, and flooring. Crape myrtle (L. indica) is used as a decorative tree. It flowers early in the summer and produces seedpods that contains the alkaloids of interesting biological activity [12].Powdery mildew has frequently been observed on sycamore plants in Jeonnam province, South Korea since it was reported by Lee et al. [13]. The use of biocontrol agents is encouraged for the control of this disease to enhance environmental sust...