The challenge of understanding the origin, pathways and extent of fungal invasions: global populations of the Neofusicoccum parvum–N. ribis species complex

Abstract

Aim Cryptic species in the Neofusicoccum parvum–N. ribis species complex have only recently been described, invalidating previous interpretations on host and geographical distribution. This study aimed to characterize the diversity and distribution of these species and to understand the patterns of host association, likely origins and their patterns of spread. Location Australia, Brazil, Cameroon, Chile, China, Colombia, Ethiopia, France, Greece, India, Indonesia, Iran, Italy, Japan, Kenya, Mexico, New Zealand, Panama, Portugal, Puerto Rico, South Africa, South Korea, Spain, Swaziland, Taiwan, Thailand, Uganda, United States of America, Uruguay, Zambia and Zimbabwe. Methods Using the unique polymorphisms that separate species within the complex, we evaluated sequence search results available in public and in our own databases. In addition, the global distribution of diversity of N. parvum was analysed using seven microsatellite markers. Results Neofusicoccum parvum is found in 90 hosts across six continents and 29 countries. Neofusicoccum kwambonambiense is found on four continents, six countries and on 14 hosts; N. occulatum is found on four continents, four countries and on 11 hosts; N. umdonicola is found on two continents, countries and hosts; N. cordaticola is found on three continents, countries and hosts; N. batangarum is found on two continents, three countries and three hosts; and N. ribis is found on one host in one country. Population genetic analysis of the global N. parvum population reflects admixture and repeat introductions. Main conclusions This study illustrates the unfettered and frequent movement of latent pathogens across international borders. Amongst the species in the N. parvum–N. ribis complex, N. parvum is the most widespread and has been reported on the majority of the hosts studied. The current dispersal of N. parvum and its sister species is probably due to repeated introductions of plant material into new growing areas, with Eucalyptus and Vitis vinifera being two prominent candidates for material transfer.

The distribution of genetic diversity in the Neofusicoccum parvum / N. ribis complex suggests structure correlated with level of disturbance

“…ribis complex has recently been characterized (Sakalidis et al, 2013). That study confirmed the widespread and generalist pathogen status of N. parvum, which was shown to occur on 90 hosts across six continents.…”

“…ribis complex, including N. batangarum (Begoude et al, 2010), N. occulatum and Neofusicoccum sp. karanda (Sakalidis et al, 2011).…”

Botryosphaeriaceae species overlap on four unrelated, native South African hosts

“…However, we do not expect that this pattern reflects host specificity in these cases, because all the fungi are known from previous studies to have broad host ranges. In particular, B. dothidea, L. theobromae and N. parvum are known to have extremely broad host ranges (Punithalingam 1976;Sakalidis et al 2013;. In South Africa, B. dothidea, has been reported previously from Acacia spp., Eucalyptus spp., Podocarpus spp., Syzygium spp.…”

Corruption, development and governance indicators predict invasive species risk from trade

“…Vegetable material included cut flowers/foliage, fresh produce, medicine/herbal treatments, nursery stock, other plant material and seeds or grain. Studies have found that vegetable material such as flower cuttings and nursery stock are important vectors of exotic species [15,16]. Timber items included bamboo, cane, rattan items, basketware, timber, wood items and willow.…”