Title : Genetic breeding as a tool to control the pine wilt disease
Abstract:
Pine wilt disease (PWD) is caused by the pine wood nematode (PWN), Bursaphelenchusxylophilus, which is transmitted by a vector of the Monochamus genus. This nematode is an invasive pest that nowadays constitutes the greatest menace to conifer forests, mainly pine forests, worldwide. It is native to North America, where it´s non-pathogenic; it has been introduced to East Asia and Portugal and has caused severe environmental and economic losses. In Spain five outbreaks have been declared, three of which are still active.The forecasted losses for Spain are higher than 11 billion euros for 2008-2030. The main host species in Europe is maritime pine (Pinuspinaster), however radiata pine (P. radiata) and Austrian pine (P. nigra) have also been affected. Breeding for resistance or tolerance is presented here as one of the main strategies to fight against this disease.Resistance or tolerance to this nematode has been included in the Galician P. pinaster and P. radiata breeding programs. Since 2013 we have performed several inoculation assays under greenhouse conditions with the aim of findingresistant or tolerant genetic materials which could be included in the Spanish National List of Basic Materials to produce Forest Reproductive Materials for new plantations. We performed inoculation assays on different genetic materials (species, provenances and families). We found significant differences at the three genetic levels. When working with P. pinaster and P. radiata families, the character resistance or tolerance to PWN was found to be genetically controlled, since some families of both species were less susceptible to this nematode than the other evaluated ones. Moreover,some individuals of both species were inoculated more than once and they remained asymptomatic. All of these indicate that genetic breeding could be a possible strategy to control the terrible disease caused by the PWN. Additionally we studied different constitutive chemical compounds trying to find if any of them could be related to theB. xylophilus resistance or tolerance. Our results show that it is possible that some of the studied compounds could be related to it, as a good relationship was found at species level. If this relationship also worked at family level, these constitutive chemical compounds could be used as a proxy for resistance or tolerance.
