Maja Mengistu M, Kasurinen Anne, Holopainen Toini, Kontunen-Soppela Sari, Oksanen Elina, Holopainen Jarmo K
Department of Environmental Science, University of Eastern Finland, PO Box 127, Kuopio, Finland
Department of Environmental Science, University of Eastern Finland, PO Box 127, Kuopio, Finland.
Tree Physiol. 2015 Sep;35(9):975-86. doi: 10.1093/treephys/tpv052. Epub 2015 Jun 19.
Climate warming is having an impact on distribution, acclimation and defence capability of plants. We compared the emission rate and composition of volatile organic compounds (VOCs) from silver birch (Betula pendula (Roth)) provenances along a latitudinal gradient in a common garden experiment over the years 2012 and 2013. Micropropagated silver birch saplings from three provenances were acquired along a gradient of 7° latitude and planted at central (Joensuu 62°N) and northern (Kolari 67°N) sites. We collected VOCs emitted by shoots and assessed levels of herbivore damage of three genotypes of each provenance on three occasions at the central site and four occasions at the northern site. In 2012, trees of all provenances growing at the central site had higher total VOC emission rates than the same provenances growing at the northern site; in 2013 the reverse was true, thus indicating a variable effect of latitude. Trees of the southern provenance had lower VOC emission rates than trees of the central and northern provenances during both sampling years. However, northward or southward translocation itself had no significant effect on the total VOC emission rates, and no clear effect on insect herbivore damage. When VOC blend composition was studied, trees of all provenances usually emitted more green leaf volatiles at the northern site and more sesquiterpenes at the central site. The monoterpene composition of emissions from trees of the central provenance was distinct from that of the other provenances. In summary, provenance translocation did not have a clear effect in the short-term on VOC emissions and herbivory was not usually intense at the lower latitude. Our data did not support the hypothesis that trees growing at lower latitudes would experience more intense herbivory, and therefore allocate resources to chemical defence in the form of inducible VOC emissions.
气候变暖正在对植物的分布、适应和防御能力产生影响。在2012年和2013年的一项共同园试验中，我们比较了沿纬度梯度的白桦（Betula pendula (Roth)）种源挥发性有机化合物（VOCs）的排放速率和组成。从沿7°纬度梯度的三个种源获取微繁殖白桦树苗，并种植在中部（约恩苏，北纬62°）和北部（科拉里，北纬67°）地点。我们收集了嫩枝排放的VOCs，并在中部地点三次、北部地点四次评估了每个种源三种基因型的食草动物损伤水平。2012年，生长在中部地点的所有种源树木的总VOC排放速率高于生长在北部地点的相同种源树木；2013年情况相反，因此表明纬度有可变影响。在两个采样年份中，南部种源的树木的VOC排放速率低于中部和北部种源的树木。然而，向北或向南迁移本身对总VOC排放速率没有显著影响，对昆虫食草动物损伤也没有明显影响。当研究VOC混合组成时，所有种源的树木通常在北部地点排放更多的绿叶挥发物，在中部地点排放更多的倍半萜。中部种源树木排放的单萜组成与其他种源不同。总之，种源迁移在短期内对VOC排放没有明显影响，在较低纬度食草作用通常不强烈。我们的数据不支持低纬度地区生长的树木会遭受更强烈食草作用，因此会以诱导性VOC排放的形式将资源分配给化学防御的假设。
