GENETIC DIVERSITY OF USTILAGO SCITAMINEA IN MAINLAND CHINA

摘要

In order to study the genetic diversity of sugarcane smut fungus Ustilago scitaminea Syd., single spore of 18 isolates were obtained from single smut whip in six different provinces in Mainland China. Total 13 random primers of 10 bp were occupied in analyses of molecular diversity by random amplified polymorphic DNA or RAPD. The largest dissimilarity coefficient was 0.89, being observed in two isolates with codes of 7 and 9 originated from Fujian and Guangxi, respectively; and the smallest one of 0.25 in two isolates originated in Fujian. Dendrogram of UPGMA cluster analysis revealed that 18 isolates of the fungus were clustered into six groups according to the dissimilarity coefficient of 0.70. Because of small dissimilarity coefficient, seven isolates originated from Fujian belonged to two different genetic groups of cluster Ⅰ and cluster Ⅱ. Four isolates originated from Guangxi were divided into four clusters, that is, clusters Ⅰ, Ⅲ, Ⅳ and Ⅴ, respectively, suggesting that the genetic diversity of the pathogen population may be higher in Guangxi. Similar phenomenon was observed in the isolates originated from Yunnan and those from Jiangxi. High dissimilarity coefficient of 0.82 was observed in two isolates collected from the same host origin but with different geographical origin. At the same time, small dissimilarity coefficients were observed in seven isolates of Fujian, collected in different varieties but with same geographical origin. The results of cluster analysis suggested that the molecular variation and differentiation was associated in some degree with geographical origin, but not suitable to all isolates. It was may be due to the frequent exchange of sugarcane varieties and clones in the recent years. Molecular diversity was not found related to the host origin.