Restriction fragment length polymorphisms in Fusarium oxysporum f.sp. dianthi and other fusaria from Dianthus species

DNA restriction fragment length polymorphisms (RFLPs) among 46 isolates of Fusarium oxysporum from Dianthus spp., representing the known range of pathogenicity in carnation, were determined using total DNA digested with the restriction enzyme HindIII and a previously described probe, D4. Distinct multiple band RFLP patterns were found, which delineated RFLP groups as follows: (i) F. oxysporum f.sp. dianthi races I and 8; (ii) F. oxysporum f.sp. dianthi races 2, 5 and 6; (iii) F. oxysporum f.sp. dianthi race 4; (iv) a recently described race of F. oxysporum f.sp. dianthi (wilt‐causing isolates from D. caryophyllus formerly classified as F. redolens); (v) wilt‐causing isolates from D. barbatus formerly classified as F. redolens and (vi), (vii) and (viii), three further recently described races of F. oxysporum f.sp. dianthi. Isolate groups derived from analysis of RFLPs were consistent with existing and recently described vegetative compatibility groups (VCGs) in F. oxysporum f.sp. dianthi, but not in all cases with races. Isolates of F. oxysporum and F. proliferatum not associated with wilt disease had simpler RFLP patterns (with one exception) that were not associated with VCGs.