Differentiation of species of Elsinoe associated with scab disease of Proteaceae based on morphology, symptomatology, and ITS sequence phylogeny

Scab disease of Proteaceae, which was initially observed on Leucospermum in South Africa in 1981, has subsequently been reported on this host from Aus tralia and Hawaii. The disease, commonly known as corky bark or scab, is as sociated with severe losses of commercial plantings of Leucospermum in Sout h Africa, and has also been collected from species of Leucadendron, Protea and Serruria in South Africa, from Banksia, Leucadendron, Mimetes, Protea a nd Serruria in Australia, and from Leucospermum and Protea in California an d Zimbabwe. The causal agent was determined to be a species of Elsinoe whic h has not been formally described. The aim of the present study was to eluc idate the taxonomy of the species of Elsinoe associated with scab disease o f Proteaceae in these countries. Morphology, symptomatology and DNA sequenc e analysis of the 5.8S rDNA gene and its flanking ITS1 and ITS2 regions wer e used. Anamorph and teleomorph characteristics of isolates from Leucosperm um, Protea and Banksia suggest that there are at least four distinct specie s involved. These findings are strongly supported by the phylogenetic tree inferred from DNA sequence data. Furthermore, these results also show that the Elsinoe isolates from Leucadendron, Leucospermum and Serruria in South Africa and Australia, and the isolates from Leucospermum in California and Zimbabwe are representative of the same species.