Interactive Effects of Microbes and Nitrogen on Panicum virgatum Root Functional Traits and Patterns of Phenotypic Selection
Interactive Effects of Microbes and Nitrogen on Panicum virgatum Root Functional Traits and Patterns of Phenotypic Selection
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DOI：
10.1086/706198
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发表时间：
2020-01
影响因子：
2.3
通讯作者：
Renee H. Petipas;A. Bowsher;Cody S. Bekkering;C. N. Jack;Emily E. Mclachlan;R. White;Brett S. Younginger;L. Tiemann;S. Evans;M. Friesen
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作者：
Renee H. Petipas;A. Bowsher;Cody S. Bekkering;C. N. Jack;Emily E. Mclachlan;R. White;Brett S. Younginger;L. Tiemann;S. Evans;M. Friesen
研究的前提。自然和农业系统中的植物受到其微生物群落的多种方式的影响，特别是通过提供改变植物功能特征的商品和服务。微生物被认为是改变植物性状表达的环境背景中有影响力的一部分，但通常情况下，微生物介导的影响取决于当地的资源，如氮。在这里，我们问微生物和氮素是如何影响地下功能性状和表型选择模式的。方法论。我们以柳枝菊(Panicum Virgatum)为材料，进行了一次完全析因温室实验，研究了微生物群落组成和氮素有效性。我们测量了植物的表现和地下功能性状，并对与根相关的微生物群落进行了16S扩增序列测定。我们寻找微生物类群和根功能性状之间的相关性，并对5个地下功能性状进行表型选择分析，以确定这些性状在生物和非生物环境中如何影响植物的相对表现。关键成果。除根组织密度外，所有地下植物功能性状均受施氮量的影响。我们发现小单孢菌属中的一个微生物分类群(扩增序列变体[ASV])与较短的根长相关。我们还发现，无论是非生物环境还是生物环境，对较长的根都有很强的正向选择。相反，在高氮条件下，选择有利于较低的根冠比，而在高氮水平和扰乱微生物群落的处理中，对根组织密度的选择最高。结论。我们没有检测到微生物对植物性状表达的影响(生态效应)；然而，对根组织密度的表型选择(进化效应)模式因生物和非生物环境而异。此外，我们检测到在不同处理中对增加根长的强烈选择；我们还发现一个ASV与根长减少相关，这表明根微生物组成分和植物适合度之间存在潜在的冲突。未来的工作将是将微生物分类群纳入表型选择分析，并对与功能特征相关的微生物进行操纵，以确定因果关系。
Premise of research. Plants in natural and agricultural systems are influenced in myriad ways by their microbial communities, particularly by providing goods and services that change plant functional traits. Microbes are considered an influential part of the environmental context that change plant trait expression, but often, microbe-mediated effects are contingent on local resources, such as nitrogen. Here, we ask how microbes and nitrogen affect belowground functional traits and patterns of phenotypic selection. Methodology. We performed a fully factorial greenhouse experiment with switchgrass (Panicum virgatum), manipulating microbial community composition and nitrogen availability. We measured plant performance and belowground functional traits and performed 16S amplicon sequencing of the root-associated microbial communities. We looked for correlations between microbial taxa and root functional traits, and we performed phenotypic selection analysis on five belowground functional traits to determine how traits affect plant relative performance across biotic and abiotic contexts. Pivotal results. All belowground plant functional traits except root tissue density were affected by adding nitrogen. We found that a microbial taxon (amplicon sequence variant [ASV]) in the genus Micromonospora correlated with shorter root lengths. We also found strong positive selection for longer roots regardless of the abiotic or biotic environment. In contrast, selection favored lower root-to-shoot ratios in high-nitrogen conditions, and selection on root tissue density was highest in treatments that had high nitrogen levels and perturbed microbial communities. Conclusions. We did not detect microbial effects on the expression of plant traits (ecological effects); however, patterns of phenotypic selection (evolutionary effects) on root tissue density differed depending on the biotic and abiotic environment. Additionally, we detected strong selection for increased root length across treatments; we also found that one ASV correlated with decreased root length, indicating potential conflict between root microbiome components and plant fitness. Future work would be to include microbial taxa in phenotypic selection analysis and to conduct manipulations of the microbes correlated with functional traits to determine causality.