Studies On Taxonomy, Phylogeny And Flora Of Powdery Mildews(Erysiphales) In The Qinling Mts.

Powdery mildews(Erysiphales) are some of the world’s most frequently encountered plant pathogenic fungi, they can infect many different kinds of plants, which results in extreme harm to the growth and development of crops, vegetables, trees, flowers and grass, and produce significant impacts on their biological yields and quality. To demonstrate the species, molecular phylogeny and flora distribution of the Erysiphales in the Qinling mountains, A total of 820 specimens, including 170 specimens taken from the Qinling mountains by previous collection, were investigated and collected from 2009 to 2014.. In this research, the morphological characteristics of teleomorph and anamorph of Erysiphales were studied by traditional taxonomic using microscope and scanning electron microscopy(SEM). Furthermore, by r DNA-28 S and r DNA-ITS sequencing analyses of Erysiphales, the molecular phylogenetic relationship of these powdery mildew species was discussed, and the flora distribution of Erysiphales in the Qinling mountains was also analyzed. The main results in this study were as follows:1. According to the new system of classification of Erysiphales, 5 Tribe, 10 genera, 98 species were identified, including 1 new species(Podosphaera girardiniae Z. M. Cao & L. C. Bai), 2 new record species(Erysiphe howeana and Erysiphe pulchra), 3 species of new record host plants in which Podosphaera tridactyla was first reported on Prunus hypoleuca. The morphological characteristics of each species of powdery mildew identified in the Qinling mountains were described in detail, and their classification statuses were assessed and citied. These hosts of these powdery mildew species involved 54 families, 125 genera, 216 species of forest plants in the Qinling mountains.2. r DNA-ITS and r DNA-28 S sequence analysis can be consistent divided more than 70 species of powdery mildews into 5 Tribes, 10 genera. Tribe Erysipheae contain only one genus: Erysiphe emend. including Sect. Erysiphe, Sect. Microsphaera and Sect. Uncinula, the species of these sections formed several small mixed clusters which cannot be phylogenetically distinguished from each other. Tribe Golovinomycetinae contain three genera: Golovinomyces, Neoerysiphe and Arthrocladiella formed a cluster. Tribe Cystotheceae contain three genera: 1 species of Cystotheca genus, 11 species of Podosphaera genus and 3 member of Sawadaea genus are composed a cluster. Tribe Phyllactinieae contain two genera: 1 species of Leveillula genus and several member of Phyllactinia genus are composed a cluster. Tribe Blumerieae with Blumeria genus, 1 species is composed a independent acluster. Molecular phylogeny of these powdery mildew species strong support their morphological classification results, also the anamorph species were identified as their teleomorph species according to the conidiogenous events, surface characters and sequence analysis of the powdery mildew conidia.3. The flora analysis revealed that Erysiphe emend. in the Qinling mountains were predominant, a total of 53 genera, accounting for 55.1% of the total known species, followed by Phyllactinia(13.3%), Golovinomyces(11.2%), Podosphaera emend(11.2%), the other is accounted for 9.2%. The consitituent analysis of host plans of these powdery mildews showed that Asteraceae accounted for 17.4%, was the main host of Erysiphales in the Qinling mountains, followed by Leguminosae, accounted for 11.7%. The vertical distribution of the powdery mildews was obvious in the Qinling mountains. Most of species distributed in alt. 1300–2800 m of needle broadleaf mixed forest zones, which are about 78.6% of total known species, there were fewer species of powdery mildews distributing in alt. 600–1300 m of broad-leaved forests zones and rare in the high alt., The geographical composition of Erysiphales flora in the Qinling mountains basically belongs to North temperate type(30.6%), followed by Eastern Asian type(17.3%), Old world temperate type(16.3%) and Cosmopolitan(15.3%). The endemic powdery mildew species of China accounted for 12.2%. The powdery mildew flora in the Qinling mountains showed distinct charaeterlstics of East Asia, and had closer similarity with Japan(73) and Korea(65), and had closer similarity with Inner Mongolia and Gansu, but farther to Dongbei region and Xinjiang in China. The powdery mildew flora showed the features of neighbourhood intersection, transition and ceitain uniqueness.The present research results can provide the basic data for fungus diversity research and cotrolling powdery mildews in the Qingling mountains.