A Study Of The Isolation And Identification Of Fusarium Wilt Germ In Sesame And The Characteristics Of Sesame Germplasm Anti-Fusarium Wilt Disease

Sesame (Sesamum indicum L.,2n=26), a member of Pedaliaceae family, is one of the most important oil-seed crops. The incidence rate of Sesame Fusarium wilt (SFW) is about 15%, even more than 30% in the several years. Thus SFW has significant impact on sesame seed yield and quality. SFW was caused by Fusarium oxysporum f. sp. sesame(FOS) which can infect sesame in whatever growth period. The study of isolation and identification of SFW, its infection and pathogenesis, are lag behind compare to the Fusarium wilt(FW) research in other crops such as molens, solanaceae etc. FW resistance mechanism of sesame and the development of SFW resistance breeding techniques also lagged.The 133 Fusarium fungi were isolated form the SFW plants that had got in this research. Through morphological identification,85 fungi (63.9%) are Fusarium oxysporum, which are the advantage group in SFW. Secondly,21 ones (15.8%) are Fusarium solani and the last 15 ones (10.7%) are Fusarium udum. F.oxysporum and F.udum mainly isolated form the diseased plants cultivated in Henan, about half of the F.solani came form the diseased plants in Henan province.Seven characters including colony texture, morphology of macroconidium, and microconidium, conidiogenous cell types, Pionnotes. types of microspore and chlamydospore growth were considered in cluster analysis.133 tested fungi were clustered together when setting on 77% similarity. The goodness of fit between numerical classification and morphological identification is up to 96%.After sequenced the 3 genes, ITS, EF-1alpha and SSU, it was found that Section Liseola of Fusarium sp., F.solani and F.oxysporum were unique at ITS and EF-lalpha; F.udum and F.oxysporum could not be indentified due to the low speed at evolution of the two genes. SSU sequence is too conservative to identify the F.oxysporum, F.solani, F.udum and Section Liseola.The pathogenicity tests showed that the high virulen isolates is 63 and 33 respectively by inoculation before seed germination and 6 days after germination.The field evaluation of sesame germplasm resistance against Fusarium oxysporum f. sp. sesame was conduced in the mixed disease nursey.Taking Yuzhi 11 as a contrast,16 and 31 varieties were ranked highly resistant and resistant respectively, while 99 and 5 varieties were ranked susceptible and highly susceptible respectively. And taking the index of average resistance as a contrast,31 varieties were highly resistant,44 varieties were resistant,75 varieties were susceptible and 2 varieties were highly susceptible.