|BARNES, IRENE - UNIVERSITY OF PRETORIA|
|FOURIE, ARISTA - UNIVERSITY OF PRETORIA|
|WINGFIELD, MICHAEL - UNIVERSITY OF PRETORIA|
|HARRINGTON, THOMAS - IOWA STATE UNIVERSITY|
|NC NEW, DOUGLAS - IOWA STATE UNIVERSITY|
|LUIZ, BLAINE - UNIVERSITY OF HAWAII|
|HELLER, WADE - UNIVERSITY OF HAWAII|
Submitted to: Persoonia: Molecular Phylogeny and Evolution of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/10/2018
Publication Date: 3/27/2018
Citation: Barnes, I., Fourie, A., Wingfield, M., Harrington, T., Nc New, D., Sugiyama, L.S., Luiz, B., Heller, W., Keith, L.M. 2018. New Ceratocystis species associated with rapid death of Metrosideros polymorpha in Hawai`i. Persoonia: Molecular Phylogeny and Evolution of Fungi. 40:154-181.
Interpretive Summary: The native 'ohi'a lehua (Metrosideros polymorpha) that has cultural, biological and ecological significance to Hawai'i is under serious threat by a disease phenomenon known as rapid 'ohi'a death (ROD). In this work we used a combination of the phylogenetic, morphological and biological species concepts, as well as pathogenicity tests and microsatellite analyses, to characterize isolates collected from diseased trees across Hawai'i Island. Two very distinct linages, representing new species of Ceratocystis, are described and renamed.
Technical Abstract: The native 'ohi'a lehua (Metrosideros polymorpha) has cultural, biological and ecological significance to Hawai'i, but it is seriously threatened by a disease commonly referred to as rapid 'ohi'a death (ROD). Preliminary investigations showed that a Ceratocystis species similar to C. fimbriata sensu lato was the cause of the disease. In this study, we used a combination of the phylogenetic, morphological and biological species concepts, as well as pathogenicity tests and microsatellite analyses, to characterise isolates collected from diseased 'ohi'a trees across Hawai'i Island. Two distinct lineages, representing new species of Ceratocystis, were evident based on multigene phylogenetic analyses. These are described here as C. lukuohia and C. huliohia. Ceratocystis lukuohia forms part of the Latin American clade (LAC) and was most closely associated with isolates from Syngonium and Xanthosoma from the Caribbean and elsewhere, including Hawai'i, and C. platani, which is native to eastern USA. Ceratocystis huliohia resides in the Asian-Australian clade (AAC) and is most closely related to C. uchidae, C. changhui and C. cercfabiensis, which are thought to be native to Asia. Morphology and interfertility tests support the delineation of these two new species and pathogenicity tests show that both species are aggressive pathogens on seedlings of M. polymorpha. Characterisation of isolates using microsatellite markers suggest that both species are clonal and likely represent recently-introduced strains. Intensive research is underway to develop rapid screening protocols for early detection of the pathogens and management strategies in an attempt to prevent the spread of the pathogens to the other islands of Hawai'i, which are currently disease free.