Comparative physiology of plant adaptation: resource acquisition and constraints of growing season length in balsam poplar from temperate, boreal and arctic environments

植物适应的比较生理学：温带、寒带和北极环境中香脂杨的资源获取和生长季节长度的限制

• 批准号: 41168-2010
• 负责人: Guy, Robert
• 金额: $ 3.06万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=521536
• 关键词: Comparative; physiology; plant; adaptation; resource

There is a trend toward higher photosynthetic rates in northern populations of several angiosperm tree species that may help compensate for short summers. We recently reported that greater photosynthesis in high latitude balsam poplar results from increased leaf mass and nitrogen per area, supported by an enhanced mesophyll conductance (gm). Mesophyll conductance is a measure of the ease with which CO2 travels through leaves, but its estimation is very uncertain and must be verified. An MSc student will use an on-line isotope discrimination technique to confirm and extend these observations in controlled north-south crosses of balsam poplar. We will compare balsam poplar with black cottonwood, which also shows enhanced photosynthesis in northern genotypes, but supported by a higher stomatal conductance (gs). Increased gs can improve nitrogen-use efficiency but reduces water-use efficiency. In contrast, increased gm should improve both. These different strategies may reflect differences in water supply, which is less limiting for black cottonwood from the northwest coast than for balsam poplar from the continental interior. Along other lines, we have established common gardens of a range-wide collection of balsam poplar at Vancouver and at similar latitude in Saskatchewan. Regardless of origin, all genotypes flush, grow and set bud ~5 weeks earlier in Vancouver. Consequently, although boreal trees can take advantage of earlier springs, they may capture less of the summer. At very high latitudes, these inherent responses could lead to strong negative impacts on tree growth if climate warming is sufficient to induce flushing a few extra weeks before the solstice. We will acquire data from field and chamber experiments to model these relationships. Finally, a PhD student will test assumptions that allow information on nitrogen uptake efficiency, sites of assimilation and ion flux to be extracted from N isotope discrimination data. He will examine phytogeographic patterns in source preference, discrimination and transcript abundance (nitrate and ammonium assimilation and transport gene families) in balsam poplar from warmer, high pH, nitrate-dominated soils vs. trees from colder, low pH, ammonium-dominated soils.

几种被子植物树种的北方种群有较高的光合作用速率的趋势，这可能有助于补偿短小的夏季。我们最近报道，高纬度苦瓜杨光合作用的提高是由于叶质量和单位面积氮素的增加，以及叶肉导度(Gm)的增加。叶肉电导是衡量二氧化碳通过叶片的容易程度的指标，但它的估计非常不确定，必须得到验证。一名理科硕士学生将使用在线同位素识别技术，在控制的苦瓜杨树南北杂交中确认和推广这些观察结果。我们将比较香脂杨树和黑杨，后者也显示出北方基因型的光合作用增强，但得到了更高的气孔导度(GS)的支持。增加GS可以提高氮素利用效率，但降低水分利用效率。相比之下，通用汽车的增加应该会对两者都有所改善。这些不同的策略可能反映了供水的差异，对于来自西北海岸的黑杨来说，这比来自大陆内陆的苦瓜杨限制得更少。沿着其他路线，我们在温哥华和萨斯喀彻温省建立了范围广泛的苦瓜杨树的共同花园。无论来自哪里，所有的基因型在温哥华都提前5周开花、生长和结蕾。因此，尽管北方的树木可以利用早春的机会，但它们可能会捕捉到更少的夏季。在很高的纬度，如果气候变暖足以在冬至前几周引起潮红，这些固有的反应可能会对树木的生长产生强烈的负面影响。我们将从现场和室内实验中获取数据来模拟这些关系。最后，一名博士生将测试假设，这些假设允许从氮同位素识别数据中提取关于氮吸收效率、同化部位和离子通量的信息。他将研究来自温暖、高pH、以硝酸盐为主的土壤和来自较冷、低pH、以铵为主的土壤的苦瓜杨树在来源偏好、辨别和转录物丰度(硝酸盐和铵的同化和运输基因家族)方面的植物地理模式。