| AB STRACTSStylosanthes spp., a native legume in South America, is the most important and commercial forage legume in tropical area around the world. It is widely used for forage, green manure, cover crops, erosion control, hay and meal commercial production. However stylo anthracnose, mainly caused by Colletotrichum gloeosporioides(sometimes called Glomerella cingulata), has been a global severe disease in stylo production since 1 970s. It causes stylo leaves yellow, necrotic and fallen, stem and leaf stalk wilted, flower fallen and seedless. In serious cases, the disease can cause seedlings or whole plant dead, reduce forge and seed production in large quantity, sometimes even seedless. It has caused stylo damage in China in the past 20 years. More than 3 good productive varieties have ceased because of anthracnose.Genetic diversity and pathogenic types of 43 Colletotrichum gloeosporio ides isolates from China and 276 isolates from other countries including eight isolates from non-stylo host as well as two Colletotrichum acutatum isolates were analysed using random amplified polymorphic DNA(RAPD) molecular markers on the basis of anthracnose disease investigation, sample collection and isolate single sporing and pure culture. The aim of this study is to assess and identify genetic diversity, pathogenic types and population structure of Colletotrichum gloeosporioides infecting Stylosanthes spp. in China by comparison with those in South America, Australia, and India and to provide some practical information for the strategies of stylo anthracnose-resistance breeding and disease control.7The amplified results showed a good DNA polymorphism between isolatesusing eight arbitrary l0-base oligonucleotide primers. The amplified fragments werebetween 0.3-2.8kb. A tOtal of 43 isolates collected in China grouPed with S.American isolafes in clusters 2, 3 and 6 with the majority in cluster 6 based on sixclusters of isolates from South America, the centre of origin of Sodsanthes genus.Three Chinese isolates in cluster 2, five isolates in cluster 3 and 35 in cluSter 6 whichwas formed by 4 subgroups. This indicated that a. genetic variation of COlletotrichumgloeosPorioides on stylo existed in China. lsolates in cluster 6 had a more extensivehost range. However those isolates in cluster 3 was specialized pathogen. As in theAustralian profile, all Chinese isolates in cluster 3 were collected from S guianensishosts. The hosts of isolates in cluster 2 were all the 6 stylo species exceptStylosanthes guianensis. Isolates in clusters 2 and 3 grouped closely with those fromAustralia suggested a possible Australian source. Because almost all the stylovarieties introduced in China were direct1y and indirectly from Australia before l980.Thus MPD molecular markers could be well used fOr pathogen tracing andspreading monitoring. Isolates grouped by geograPhic origin and host species orgenotypes indicated isolates from different host species or genotypes had their ownparasitic specialiZation on genetic basis and pathOgens from different countriesevolved in their own wny relativelyC1uster analysis showed the genetic variation in the Chinese and Australianpopulatiott was very limited comPared with that in South America, the cefitfe of hostopathogen diversity. A similar situation also was detected for pathogen variation inChina from this study. The genetic variation in the population in Guangdong andGuangxi was tnore 1imited than tha in Hainan. This could be related to a longhistory of growing stylQ in Hainan. So RAPD molecular markers Will be useful tobetter understand the movement of pathogen populations between geograPhicallyisolated regions.,- 8C.gloeosporioides and C. acutatum were grouped in different clusters at very beginning. This indicated RAPD molecular markers was a very sensitive and exact tool for classification and identification of Colletotorichum species. Because mycelia and conidia of different Co/letotorichum gloeosporio...
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