Evolutionary history resolves global organization of root functional traits
Evolutionary history resolves global organization of root functional traits
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DOI：
10.1038/nature25783
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发表时间：
2018-03-01
期刊：
影响因子：
64.8
通讯作者：
Hedin, Lars O.
中科院分区：
文献类型：
--
作者：
Ma, Zeqing;Guo, Dali;Hedin, Lars O.
自第一批陆地植物出现以来，植物根的形式和功能已经大大多样化(1,2)，但根中功能性状的整体组织仍然知之甚少(3,4)。在这里，我们分析了代谢活跃的一级根中 10 个功能重要的根性状的全球数据集，这些性状收集自分布在 7 个生物群落的天然植物群落中的 369 个物种。我们的结果确定了跨物种和生物群落的根性状的高度组织，并揭示了一种与基于之前的叶子性状研究（5,6）的预期不同的模式。根直径对不同植物物种、生长形式和生物群落的根性状变异影响最大。我们的分析表明，植物自从首次出现在陆地生态系统中以来，已经进化出更细的根，这使得它们能够显着提高每单位碳投入的土壤探索效率，并减少对共生菌根真菌的依赖。我们还发现，根形态性状的多样性在热带地区最大，那里的植物多样性最高，并且保留了许多祖先的系统发育群。在热带、温带和沙漠生物群落序列中，根系形态的多样性急剧下降，这可能是由于季节性恶劣的非生物条件导致资源供应的变化。我们的研究结果表明，根系性状是沿着由两种截然不同的根系生命策略所限制的范围进化的：一种是祖先的“保守”策略，其中粗根的植物依靠与菌根真菌的共生来获取土壤资源；另一种是更衍生的“机会主义”策略，其中细根使植物能够更有效地利用光合碳来探索土壤。这些发现表明，地下性状的创新在准备植物殖民新栖息地以及在生物群落内部和跨生物群落产生生物多样性方面发挥了重要作用。
Plant roots have greatly diversified in form and function since the emergence of the first land plants(1,2), but the global organization of functional traits in roots remains poorly understood(3,4). Here we analyse a global dataset of 10 functionally important root traits in metabolically active first-order roots, collected from 369 species distributed across the natural plant communities of 7 biomes. Our results identify a high degree of organization of root traits across species and biomes, and reveal a pattern that differs from expectations based on previous studies(5,6) of leaf traits. Root diameter exerts the strongest influence on root trait variation across plant species, growth forms and biomes. Our analysis suggests that plants have evolved thinner roots since they first emerged in land ecosystems, which has enabled them to markedly improve their efficiency of soil exploration per unit of carbon invested and to reduce their dependence on symbiotic mycorrhizal fungi. We also found that diversity in root morphological traits is greatest in the tropics, where plant diversity is highest and many ancestral phylogenetic groups are preserved. Diversity in root morphology declines sharply across the sequence of tropical, temperate and desert biomes, presumably owing to changes in resource supply caused by seasonally inhospitable abiotic conditions. Our results suggest that root traits have evolved along a spectrum bounded by two contrasting strategies of root life: an ancestral 'conservative' strategy in which plants with thick roots depend on symbiosis with mycorrhizal fungi for soil resources and a more-derived 'opportunistic' strategy in which thin roots enable plants to more efficiently leverage photosynthetic carbon for soil exploration. These findings imply that innovations of belowground traits have had an important role in preparing plants to colonize new habitats, and in generating biodiversity within and across biomes.