Understanding of environmental adaptation and its genetic mechanisms in boreal conifers

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Environmental adaptation and its genetic mechanisms of forest trees are recent topics in forest genetics. In this study, four studies have been conducted in the University of Tokyo Hokkaido Forest where has a 1,200-m altitudinal range. (1) We collected data of the basal area (BA) and the number of recruits for major conifers from field measurements with many plots and environmental condition from GIS analyses. We found that BA and regeneration of A. sachalinensis were dominant in low-mid elevation zones, whereas those of P. jezoensis were larger in mid-high elevation zones. (2) We examined adaptive genes derived from phenolix and terpenoids synthesis pathways to explain altitudinal differentiation. Previously-known CHS and STS genes related to phenolix showed similar patterns between high- and low-elevation trees. Then, we identified DNA sequences of PAL gene related to terpenoids in genus Picea. This sequence will be useful for developing adaptive gene markers for genus Picea. (3) We used a reciprocal transplant experiment along the altitude in A. sachalinensis and clarify whether tree height and survival rate are adaptive to native altitude. As altitudinal difference between native sites and transplanting ones increased,productivity (tree height×survival rate) decreased. Thus, home-site advantage is confirmed by the mathematical modeling. Freezing tests suggest that there is altitudinal variation in timing of cold acclimation. (4) We measured number of cones, height and diameter growth of F1 trees consisting of a reciprocal hybridization test plantation with four genetic compositions (low×low, low×high, high×low and high×high elevation). We found that reproductive traits were significantly higher in high-elevation derived trees, whereas growth traits were higher in low-elevation derived trees.