| This study is about the taxonomic research of Drechslera Ito andExsehilum Leonard & Suggs in China. About 200 isolates were receivedfrom more than 3000 herbarium specimens, which we have collected frommany provinces of China. From the isolates, we have found one new species, D. a venicola B. D.Sun et T. Y. Zhang, five Chinese new record species, D. andersenii Lam,D. sivanesanii C. Manoharachary et V. R. T. Reddy, E. frumentaeei (Mitra)Leonard & Suggs, E. pedicellatium (Henry) Leonard &Suggs and elevenspecies which had been reported in China, they are , D. avenacea(M.A.Curtis ex Cooke) Shoem., O. dictyoides (Drechsler) Shoem.,D. graminea (Rabenh. ex Schlecht.) Shoem., D. phlei (Graham) Shoem.,.D. teres (Sate.) Shoem., E. fusiforme Alcom, E. holmii (Luttr.) Lenoard& suggs, E. ]ongisporium G.Y.Sun, R.Zhang, M.Q.Zhu & T.Y.Zhang,E. monoceras(Drechsler) Leonard & Suggs, E. phragmatis W.P Wu,E. rostratum (Drechler) Leonard & Suggs and E. turcicum (Pass.) Leonard& Suggs. To investigate the genetic variation in E.rostratum, a total of 26E.rostratum isolates and 7 isolates of other species were analyzed with 10random amplified polymorphic DNA (RAPD) primers. The results showedthat there was a similar disorderliness with conidia morphology showed. Therewas a large variation among all E.rostratum isolates, and character of conidiawas not a critical criteria of relationship between isolates. We should treat allisolates of E.rostratum as one group since there were no constant crt. The conidia from culture medium shows less variety whentreated all isolates of E.rostratum as a whole, and should be treated as maincriteria of classification of this species. After many works have been done about this two genera, the main resultsof this research are the revisions of the Latin and Chinese name of the generaand the species in them. We also have found a new species, several newChinese record species and broadened the hosts' records and distribution ofsome species. All the works will contribute to the further study of this group offungi. In our research work, we ve payed a constant attention to the taxonomicmethods and the testifying and exploring of criteria to differentiate species. Westudied the culture character of all isolates, the conditions to spur Drechsleraspp to produce conidia on culture medium, the formation of conidia septum,the germ character of conidia etc, and have concluded a much easier andfeasible criteria for the classification this group of fungi. In differentiating different genera, the character of hilum plays animportant role. The hilum of Drechslera spp is atrium type hilum, which islarger and we can see them never protruding from the contour of basal cellwhen under optical microscope. Some time we can even see them were in thebasal cell of conidia, and clear of the cell wall. The hilum of Exserohilum spp.were protruding and had an enveloping structure. But this structure can not befound using optical microscope. Only that you may found an ring thickness atthe top of the hilum of E.monoceras and several other species. Thegermination character of the basal cell of conidia is useful in distinguishingDrechslera spp. from Bipolaris spp and Exserohilum spp But this character haslittle difference between the later two genera. The color of conidia only has anassitant role in genus classification. The Exserohilum spp have distoseptatesand the Curivularia spp with protruding hilum have euseptates has been seenas the main difference between them. This criteria is used even it has beendoubted because there is no other criteria better. In treating with the species, the morphology of conidia is main criteria,especialy the shape and the size of conidia, the shape of conidia cell, theconidia septum and the existence of secondary conidiophore and secondaryconidia. Some parameter such as the ratio of width of a... |
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