Understanding of environmental adaptation and its genetic mechanisms in boreal conifers

森林树木的环境适应及其遗传机制是森林遗传学研究的热点。在本次研究中，在海拔1200米的东京大学北海道森林进行了四项研究。(1)利用地理信息系统（GIS）对不同样地、不同环境条件下的主要针叶树进行了野外测量，获得了主要针叶树的基本面积（BA）和新枝数。结果表明，低、中海拔地区萨沙林a.s achalinensis的BA和再生优势明显，而中、高海拔地区空肠p.s jezoensis的BA和再生优势较大。(2)研究了来自酚类化合物和萜类化合物合成途径的适应性基因，以解释海拔差异。先前已知的与白杨相关的CHS和STS基因在高海拔和低海拔树木之间表现出相似的模式。在此基础上，鉴定了云杉属植物萜类相关PAL基因的DNA序列。该序列将为开发云杉属的适应性基因标记提供参考。(3)利用沿海拔方向的互栽实验，研究了沙卡林树高和成活率对海拔的适应性。随着原生地与移栽地高度差的增大，生产力（树height×survival率）降低。由此，通过数学建模，确定了主站优势。冰冻试验表明，在冷驯化的时间上存在海拔差异。(4)测定了4个遗传组合（low×low、low×high、high×low和high×high海拔）组成的互交杂交试验林F1树的球果数、株高和株径生长情况。研究发现，高海拔衍生树的生殖性状显著高于低海拔衍生树，而生长性状显著高于高海拔衍生树。

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.