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: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=544847
• 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存在光合速率较高的趋势，这可能有助于弥补夏季短暂的影响。 我们最近报道称，高纬度香脂杨的光合作用增强是由于叶肉导度（gm）增强，单位面积的叶质量和氮含量增加。 叶肉导度是二氧化碳通过叶子的难易程度的衡量标准，但其估计值非常不确定，必须进行验证。 理学硕士学生将使用在线同位素辨别技术来确认和扩展在受控的香脂杨南北杂交中的观察结果。 我们将香脂杨与黑三叶杨进行比较，后者在北方基因型中也显示出增强的光合作用，但具有更高的气孔导度 (gs)。 增加 gs 可以提高氮利用效率，但会降低水利用效率。 相反，增加毛重应该会改善两者。 这些不同的策略可能反映了供水的差异，对西北海岸的黑三叶杨来说，供水的限制比对大陆内陆的香脂杨的限制要小。 除此之外，我们还在温哥华和萨斯喀彻温省类似纬度地区建立了种植各种香脂杨的公共花园。 无论起源如何，所有基因型在温哥华都会提前约 5 周开花、生长和开花。 因此，尽管北方树木可以利用较早的春季，但它们在夏季的利用时间可能会较少。 在极高纬度地区，如果气候变暖足以在夏至前几周引发潮水，这些固有反应可能会对树木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，一名博士生将测试一些假设，这些假设允许从氮同位素辨别数据中提取有关氮吸收效率、同化位点和离子通量的信息。 他将研究来自较温暖、高 pH 值、以硝酸盐为主的土壤的香脂杨与来自较冷、低 pH 值、以铵为主的土壤的香脂杨在来源偏好、辨别和转录本丰度（硝酸盐和铵同化和运输基因家族）方面的植物地理学模式。