Schueler Silvio, George Jan-Peter, Karanitsch-Ackerl Sandra, Mayer Konrad, Klumpp Raphael Thomas, Grabner Michael
Department of Forest Growth, Silviculture and Genetics, Austrian Research Centre for Forests BFW, Vienna, Austria.
Department of Material Sciences and Process Engineering, Institute of Wood Technology and Renewable Resources, University of Natural Resources and Life Sciences (BOKU), Tulln an der Donau, Austria.
Front Plant Sci. 2021 Jul 8;12:648312. doi: 10.3389/fpls.2021.648312. eCollection 2021.
Intraspecific genetic variation in drought response is expected to play an important role in determining the persistence of tree populations in global change as it (1) allows for spontaneous selection and local adaptation of tree populations, (2) supports assisted seed transfer of less-drought-sensitive provenance, and (3) enables the integration of drought-sensitivity traits into tree breeding. Estimating the potential of such adaptation options requires quantitative genetic knowledge of drought sensitivity across significant parts of species distributions and a comparative assessment of genetic variation within economically and ecologically important tree species. We quantified genetic variation within and among populations of four conifers growing within common garden experiments in the drought-prone eastern Austria. This region experienced three strong drought periods between 1980 and 2010 that resulted in significant reductions in radial growth. Among the four tested species, Douglas-fir revealed the highest resistance during drought and silver fir the best recovery after drought, while European larch and Norway spruce showed the lowest resistance. High genetic variation among populations and phenotypic stability across all three drought events was found for Norway spruce and silver fir, but not for the other species. Heritability and evolvability of drought traits, both approximated genetic repeatability, revealed strong differences among populations of all four species. Repeatability and evolvability for resistance were highest in Norway spruce and, for recovery, highest in European larch. Our comparison indicates that the mean drought sensitivity of a species is not related to the intraspecific genetic variation in drought response. Thus, also highly drought-sensitive species, such as Norway spruce and European larch, harbor significant genetic variation in drought response within and among populations to justify targeted tree breeding, assisted gene flow, and supportive forest management to foster local adaptations to future conditions.
干旱响应中的种内遗传变异有望在决定树木种群在全球变化中的持久性方面发挥重要作用，因为它（1）允许树木种群进行自然选择和局部适应，（2）支持对干旱敏感性较低的种源进行辅助种子转移，以及（3）使干旱敏感性性状能够融入树木育种。估计这些适应选项的潜力需要了解物种分布的重要部分中干旱敏感性的数量遗传学知识，以及对经济和生态上重要的树种内的遗传变异进行比较评估。我们对生长在奥地利东部干旱多发地区的四个针叶树种在共同园试验中的种群内和种群间的遗传变异进行了量化。该地区在1980年至2010年期间经历了三个严重干旱期，导致径向生长显著减少。在四个测试物种中，花旗松在干旱期间表现出最高的抗性，而银枞在干旱后恢复得最好，而欧洲落叶松和挪威云杉的抗性最低。挪威云杉和银枞在种群间表现出高遗传变异，并且在所有三个干旱事件中表现出表型稳定性，而其他物种则不然。干旱性状的遗传力和进化能力（两者都近似于遗传重复性）在所有四个物种的种群间表现出强烈差异。挪威云杉的抗性重复性和进化能力最高，而欧洲落叶松的恢复重复性和进化能力最高。我们的比较表明，一个物种的平均干旱敏感性与干旱响应中的种内遗传变异无关。因此，即使是对干旱高度敏感的物种，如挪威云杉和欧洲落叶松，在种群内和种群间的干旱响应中也存在显著的遗传变异，这证明了有针对性的树木育种、辅助基因流动和支持性森林管理以促进对未来条件的局部适应是合理的。
