Xylella fastidiosa – a new menace for Portuguese agriculture and forestry

Abstract

Xylella fastidiosa is a gram-negative bacterium classified as a quarantine pest by EPPO (A1 list), since 1981. Is a xylem-limited bacteria, with a wide host range (more than 300 species), that affects economically important agricultural crops. It is a challenge of almost 30 years in America for grapevine (Pierce's disease) and citrus (Citrus Variegated Chlorosis) farmers. The first outbreak in Europe was reported in October 2013 in southern Italy, in Puglia region, Salento area. The CoDiRO strain (Xylella fastidiosa subsp. pauca) was responsible for the named – Complesso del disseccamento rapido dell'olivo (CoDiRO). More than 8000 ha of olive trees have been destroyed and nearly 21 000 ha are in quarantine, which counts for more than 53 million euros in losses. It was confirmed, in January 2015, by the European Food Safety Authority, that, the X. fastidiosa spreading is far from being contained. EFSA experts have alerted European countries that X. fastidiosa is now “very likely” to spread, posing a major risk to European olive trees and have warned that the disease is a “very serious threat” to European agriculture. There is no record of successful eradication of X. fastidiosa once it has been established. A wide-ranging research is necessary because X. fastidiosa has a remarkable power of adaptation. It has been proven that introgression events allowed X. fastidiosa to access new hosts. Its natural competence to acquire new genes turns it into a phytopatogen with all the necessary conditions to adapt almost to any ecological niche.