Molecular characterisation and pathogenicity of Phaeoacremonium spp. associated with esca disease of grapevine in Northern Iran.

Esca is a very important and destructive disease of grapevine in many grapevine producing countries. Several groups of fungi have been reported from grapevines with esca disease symptoms; however,Phaeoacremoniumspecies are the main hyphomycete fungi involved in this disease. In recent years, esca disease symptoms with consequent decline disease have frequently been observed in vineyards of north-western Iran. Nevertheless, the involvement ofPhaeoacremoniumspp. with esca disease symptoms in this region remains unknown. During 2008–2010 growing seasons, wood samples were collected from vines showing typical esca disease symptoms such as interveinal leaf chlorosis with subsequent necrosis and various types of internal wood deterioration in north-western parts of Iran. A total of 44Phaeoacremonium-like hyphomycetes were recovered from sampled materials. Fungal isolates were subjected to tentative morphological identification and were further characterised by using sequenced data from ITS-rDNA and β-tublin gene. Phylogeny inferred using sequence data from ITS-rDNA region and β-tublin gene revealed thatPhaeoacremonium aleophilumandP. mortoniaetogether withSarocladium strictum(syn.Acremonium strictum) are associated with esca disease symptoms in this region. The pathogenicity ofPhaeoacremoniumspp. andSarocladium strictumwere verified by the inoculation of cutting root and stems under greenhouse conditions. Isolates ofP. aleophilumandP. mortoniaewere the most virulent based on the length of vascular necrosis on woody stems that followed bySarocladium strictum. This is first study on the pathogenicity ofSarocladium strictumon grapevine worldwide and the first report on the occurrence ofP. mortoniaeon grapevines in north-western Iran. [ABSTRACT FROM PUBLISHER]