Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640;
Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ 86011-6077.
Proc Natl Acad Sci U S A. 2017 Oct 17;114(42):11169-11174. doi: 10.1073/pnas.1704022114. Epub 2017 Sep 25.
Plant genetic variation and soil microorganisms are individually known to influence plant responses to climate change, but the interactive effects of these two factors are largely unknown. Using long-term observational studies in the field and common garden and greenhouse experiments of a foundation tree species () and its mutualistic ectomycorrhizal fungal (EMF) associates, we show that EMF community composition is under strong plant genetic control. Seedlings acquire the EMF community of their seed source trees (drought tolerant vs. drought intolerant), even when exposed to inoculum from the alternate tree type. Drought-tolerant trees had 25% higher growth and a third the mortality of drought-intolerant trees over the course of 10 y of drought in the wild, traits that were also observed in their seedlings in a common garden. Inoculation experiments show that EMF communities are critical to drought tolerance. Drought-tolerant and drought-intolerant seedlings grew similarly when provided sterile EMF inoculum, but drought-tolerant seedlings grew 25% larger than drought-intolerant seedlings under dry conditions when each seedling type developed its distinct EMF community. This demonstration that particular combinations of plant genotype and mutualistic EMF communities improve the survival and growth of trees with drought is especially important, given the vulnerability of forests around the world to the warming and drying conditions predicted for the future.
植物遗传变异和土壤微生物都被认为会单独影响植物对气候变化的响应，但这两个因素的交互作用在很大程度上是未知的。本研究通过长期野外观测研究、乡土树种及其共生外生菌根真菌（EMF）的共同花园和温室实验，表明 EMF 群落组成受到植物遗传的强烈控制。即使暴露于来自交替树种的接种物，幼苗也会获得其种子源树木的 EMF 群落（耐旱与不耐旱）。在野外干旱 10 年的过程中，耐旱树种的生长速度比不耐旱树种高 25%，死亡率低 30%，这些特性在共同花园中的幼苗中也有观察到。接种实验表明，EMF 群落对耐旱性至关重要。当提供无菌 EMF 接种物时，耐旱和不耐旱的幼苗生长情况相似，但当每种幼苗类型形成其独特的 EMF 群落时，耐旱幼苗在干旱条件下的生长速度比不耐旱幼苗大 25%。鉴于全世界的森林都容易受到未来变暖变干条件的影响，这种耐旱植物特定的基因型和共生 EMF 群落组合提高树木存活率和生长的证明尤其重要。
