Identification On The Variety Of Gaeumannomyces Graminis Of Wheat In Hebei Province And The Study On Techniques Of Molecular Diagnosis

The 89 samples of wheat roots infected by Gaeumannomyces graminis were collected from Xingtai, Shijiazhuang and Baoding. The strains were isolated from diseased roots and 62 strains were obtained after purification. The results of morphology identification indicated that the runner hypha of the 62 strains was brown and showed" A" at the branch. All the strains can produce phialid and phialospores. The phialospore is lunular or semilunar and the size is 3～7μm×1～2μm. All the strains can only produce simple hyphopodium which is olivary, claviform or near orbicular. The hyphopodium usually produce together and form sclerotic masses. The perithecium is produced immerge or semi-immerge, and the neck stretches out the medium. The perithecium is occasionally produced between the hypha of the bottles. The perithecium is orbicular or olivary and the size is 396～485 urn. The mature ascus is clavate and the size is 104～125μm×9～15μm. Ascospores are linear and slight curving. The mature ascospore has clear membrane and the size is 73～92μm×3～4μm.Morphological and physiological characteristics study of the strains showed that the colonies were round on the PDA medium. The colony colour was hoar during the early stage and then changed to taupe at the late stage. The margin of the colony was curled to the center. Growth rate of most isolates increased on PDA media containing 1% L-cysteine. Growth rate of all the isolates were inhibited on PDA media containing 2.5% fresh oat leaves soap. The optimal temperature of most isolates is 25℃, and the optimal pH is 7.0-8.0.The result of pathogenicity of G. graminis to cereals including wheat, sorghum, rice, oat and maize indicated: All the strains could not infect oat and could infect wheat, sorghum, rice and maize. The strains damaged wheat heaviest.The primers designed by Rachadwong and Wang Meinan were used to identify the 62 strains. The results indicated that all the strains can only get the 870bp fragment which belongs to Ggt, while no other special fragments obtained. According to the above characteristic, all the 62 strains were identified as G. graminis var. tritici.The primer Ggt:AV3 was used to detecte Ggt in the diseased roots of wheat. All the roots inoculated with Ggt were amplified 870 bp fragment. The roots that did not inoculate and inoculated with Rhizoctonia cerealis, Rhizoctonia solani, Helminthosporium spp., Alternaria spp., Fusarium graminearum can not amplified 870 bp fragment. The primer Ggt: AV3 can amplify 870bp fragment in different severity wheat. With the increase of the severity, the width and brightness of the band was increased. It indicated that the primers could be used to diagnosis or predict the disease of wheat take-all.