Lodgepole pine provenances differ in chemical defense capacities against foliage and stem diseases

Maximization of lodgepole pine (Pinus contorta Douglas ex Louden var. latifolia Engelm. ex S. Watson) growth in a future climate with increased pest activity requires an understanding of the natural variability of quantitative resistance to disease. Foliar and bark secondary metabolites from different lodgepole pine provenances (populations) were quantified and correlated with severity of foliar diseases caused by Lophodermella spp. (Lophodermella concolor (Dearn.) Darker or Lophodermella montivaga Petre. ) or Elytroderma deformans (Wier) Darker and bark diseases caused by Elytro- derma or Endocronartium harknessii (J.P. Moore) Y. Hiratsuka. Greater foliar concentrations of lignin, tannins, and some phenolics were associated with increased resistance to single or multiple foliar pathogens. Bark secondary metabolites lev- els were generally unassociated with resistance to bark diseases. Provenances appearing to originate in ecosystems where lodgepole pine are not the dominant species generally were more susceptible to foliar diseases and had less foliar defense- associated compounds than trees from areas where pines were the dominant species, yet clear trends proved to be elusive. Regardless, pine provenances with greater foliar levels of identified defense-associated compounds should be preferred seed sources for replanting forests in areas in which foliar disease is expected to be increasingly prevalent. Resume´ : Il faut connaitre la variabilitenaturelle de la resistance quantitative aux maladies pour maximiser la croissance du pin tordu latifolie ´ (Pinus contorta Douglas ex Louden var. latifolia Engelm. ex S. Watson) car les conditions climati- ques devraient, dans l'avenir, entrainer une augmentation de l'activitedes ravageurs. Les metabolites secondaires des feuil- les et de l'ecorce de differentes provenances (populations) de pin tordu latifolieont etequantifies et correles avec la severitedes maladies de feuilles causees par Lophodermella spp. (Lophodermella concolor (Dearn.) Darker ou Lophoder- mella montivaga Petre. ) ou Elytroderma deformans (Wier) Darker et des chancres causes par Elytroderma ou Endocronar- tium harknessii (J.P. Moore) Y. Hiratsuka. Des concentrations plus elevees de lignine, de tannins et de certains composes phenoliques etaient associesaune plus grande resistance aun ou plusieurs pathogenes foliaires. Le niveau de metabolites secondaires dans l'ecorce n'etait pas generalement associeala resistance aux chancres. Il semble que les provenances as- sociees ades ecosystemes oule pin tordu latifolien'est pas l'espece dominante etaient generalement plus sensibles aux maladies de feuilles et avaient moins de composes foliaires relies aux mecanismes de defense que les arbres qui prove- naient des zones oules pins etaient l'espece dominante; mais il n'y avait pas de tendances nettes. Malgretout, les prove- nances de pin avec les niveaux les plus eleves de composes connus associes aux mecanismes de defense dans les feuilles devraient etre les sources preferees de graines pour replanter les forets dans les zones oules maladies de feuilles pour- raient etre de plus en plus repandues. (Traduit par la Redaction)