Tellez Peter H, Arnold A Elizabeth, Leo Ashton B, Kitajima Kaoru, Van Bael Sunshine A
Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, United States.
School of Plant Sciences, University of Arizona, Tucson, AZ, United States.
Front Microbiol. 2022 Jul 28;13:927780. doi: 10.3389/fmicb.2022.927780. eCollection 2022.
Leaf traits of plants worldwide are classified according to the Leaf Economics Spectrum (LES), which links leaf functional traits to evolutionary life history strategies. As a continuum ranging from thicker, tough leaves that are low in nitrogen (N) to thinner, softer, leaves that are high in N, the LES brings together physical, chemical, and ecological traits. Fungal endophytes are common foliar symbionts that occur in healthy, living leaves, especially in tropical forests. Their community composition often differs among co-occurring host species in ways that cannot be explained by environmental conditions or host phylogenetic relationships. Here, we tested the over-arching hypothesis that LES traits act as habitat filters that shape communities of endophytes both in terms of composition, and in terms of selecting for endophytes with particular suites of functional traits. We used culture-based and culture-free surveys to characterize foliar endophytes in mature leaves of 30 phylogenetically diverse plant species with divergent LES traits in lowland Panama, and then measured functional traits of dominant endophyte taxa . Endophytes were less abundant and less diverse in thick, tough, leaves compared to thin, softer, leaves in the same forest, even in closely related plants. Endophyte communities differed according to leaf traits, including leaf punch strength and carbon and nitrogen content. The most common endophyte taxa in leaves at different ends of the LES differ in their cellulase, protease, chitinase, and antipathogen activity. Our results extend the LES framework for the first time to diverse and ecologically important endophytes, opening new hypotheses regarding the degree to which foliar symbionts respond to, and extend, the functional traits of leaves they inhabit.
全球植物的叶片性状是根据叶片经济谱（LES）进行分类的，该谱将叶片功能性状与进化生活史策略联系起来。作为一个连续体，从含氮量低的较厚、坚韧的叶片到含氮量高的较薄、柔软的叶片，LES汇集了物理、化学和生态性状。真菌内生菌是常见的叶际共生体，存在于健康的活叶中，尤其是在热带森林中。它们的群落组成在共生宿主物种之间往往存在差异，而这种差异无法用环境条件或宿主系统发育关系来解释。在这里，我们检验了一个总体假设，即LES性状作为栖息地过滤器，在组成方面以及在选择具有特定功能性状组合的内生菌方面塑造内生菌群落。我们使用基于培养和免培养的调查方法，对巴拿马低地30种系统发育多样、具有不同LES性状的成熟叶片中的叶内生菌进行了表征，然后测量了优势内生菌类群的功能性状。与同一森林中较薄、较软的叶片相比，较厚、坚韧的叶片中的内生菌数量较少且种类较少，即使是亲缘关系密切的植物也是如此。内生菌群落因叶片性状而异，包括叶片穿刺强度以及碳和氮含量。LES不同端点叶片中最常见的内生菌类群在纤维素酶、蛋白酶、几丁质酶和抗病原体活性方面存在差异。我们的结果首次将LES框架扩展到多样且具有重要生态意义的内生菌，开启了关于叶际共生体对其栖息叶片的功能性状响应程度以及扩展程度的新假设。
