Globalisation, the founder effect, hybrid Phytophthora species and rapid evolution: new headaches for biosecurity

Host records for Phytophthora multivora associated with dieback in Victoria, Australia

“…P. multivora has been recently found causing disease within the Gondwana Rainforests of Australia World Heritage Area (Scarlett et al 2015) and the Wollemi National Park, NSW (Puno et al 2015), both eastern coastal areas of Australia. These new host reports provide support to concerns raised about the impact that P. multivora could have if spread through the Australian natural environment (Callaghan and Guest 2015;Scarlett et al 2015).…”

“…In pathogenicity trials, infesting the rhizospheres of young trees with P. multivora isolates significantly reduced the fine root surface area and the number of root tips on Eucalyptus gomphocephala and E. marginata, and under-bark inoculation caused significantly expanded rot lesions (Scott et al 2012). According to Callaghan and Guest (2015), P. multivora is now considered the second-most widespread Phytophthora species in Western Australia after P. cinnamomi, and at many sites it is P. multivora rather than P. cinnamomi that causes tree mortality. Since first described, it has been reported from declining Wollemia nobilis (Wollemi pine) in New South Wales (Puno et al 2015), lucerne (Bezuidenhout et al 2010) and citrus (Meitz-Hopkins et al 2014) in South Africa, soybean in Japan (Rahman et al 2014(Rahman et al , 2015, oaks in Hungary (Szabó et al 2013), Viburnum spp.…”

Pathogenicity of Phytophthora isolates originating from several woody hosts in Bulgaria and Poland

“…The intercontinental movement and transplantation of infected plant material partially explains the appearance of new species in unexpected places. However, it is also likely that novel species arise as a result of the hybridisation and rapid evolution of introduced species under episodic selection pressures (Callaghan and Guest 2015). Hybrid progeny may possess equal or greater virulence than parent species, thereby posing an increasing risk to our natural environment and agricultural production systems.…”

“…The oomycete genus Phytophthora comprises a large number of plant pathogens that cause significant damage to various natural and agricultural ecosystems in altered climatic zones (Callaghan and Guest 2015). Bulgaria is situated in south-eastern Europe and encompasses a wide range of environments.…”

“…The development of DNA-based technologies has revealed much broader and more complex diversity than previously recognised and has led to the recent description of many new species (Callaghan and Guest 2015). The soil-borne species Phytophthora quercina T. Jung appears to be strongly involved in the European oak decline phenomenon (Jönsson et al 2003).…”