Aleppo pine defense against Sphaeropsis sapinea, Cronartium flaccidum and other fungal pathogens in the Mediterranean part of Montenegro

Abstract

Aleppo pine (Pinus halepensis Mill.) is the most widely disturbed conifer tree in native forest and plantations throughout the Adriatic coast of Montenegro. However, pathogenic fungi in the region are extremely diversified and constitute the principal threat to healthy tree growth: 15 pathogenic fungal species have beden identified in the Eumediterranean zone - a typical habitat of Aleppo pine, whereas 21 fungal pathogens occurred in northern Submediterranean zone - an atypical habitat for Aleppo pine in Montenegro. Greatest damages are inflicted by Sphaeropsis sapinea, a pathogenic generalist on pine, and Cronartium flaccidum, causal agent of rust disease on pine. The following relates, for the first time, the presence of hypersensitive response (HR) in young needles and shoots (organs rich in nitrogen) as a specific defense mechanism in Aleppo pine against Sphaeropsis sapinea, an otherwise very harmful pathogen for Austrian pine (Pinus nigra Arn.) and other pines in the Mediterranean part of Montenegro. Thus, better understanding of the ecology of S. sapinea, of C. flaccidum, as well as of associated mycobiota and mechanisms of host defense are essential for establishing measures and tools for protection of Aleppo pine ecosystems.