Comparisons of isolates of Fusarium avenaceum from white lupin and other crops by pathogenicity tests, DNA analyses and vegetative compatibility tests

Isolates of Fusarium avenaceum, mostly from crops of white lupin or wheat, were tested for pathogenicity on white lupin and wheat plants and compared by DNA tests and, in a limited study, vegetative compatibility. Most of the 80 isolates were pathogenic on both plant species after inoculation on sho ot bases. Disease severity was greater at higher incubation temperatures th at ranged from 15/10 degrees C to 25/20 degrees C (day/night temperatures). Isolates from lupin crops tended to be more pathogenic, on average, on lup ins than on cereals. Polymerase chain reaction (PCR)-restriction fragment l ength polymorphism (RFLP) analysis of the internal transcribed spacer regio n of the rDNA distinguished two groups of isolates that occurred in differe nt proportions among isolates from lupins and cereal crops. Random amplifie d polymorphic DNA (RAPD)-PCR analyses indicated considerable genetic variat ion among isolates, but there was some similarity among groups of isolates from populations in the same field. Genetic diversity was confirmed by a hi gh degree of vegetative incompatibility among 20 isolates using nitrate non utilizing mutants. There were no relationships among pathogenicity, RFLP gr oup, RAPD group and vegetative compatibility group.