Root trait–microbial relationships across tundra plant species

Abstract

Fine roots, and their functional traits, influence associated rhizosphere microorganisms via root exudation and root litter quality. However, little information is known about their relationship with rhizosphere microbial taxa and functional guilds. We investigated the relationships of 11 fine root traits of 20 sub-arctic tundra meadow plant species and soil microbial community composition, using phospholipid fatty acids (PLFAs) and high-throughput sequencing. We primarily focused on the root economics spectrum, as it provides a useful framework to examine plant strategies by integrating the coordination of belowground root traits along a resource acquisition-conservation trade-off axis. We found that the chemical axis of the fine root economics spectrum was positively related to fungal to bacterial ratios, but negatively to Gram-positive to Gram-negative bacterial ratios. However, this spectrum was unrelated to the relative abundance of functional guilds of soil fungi. Nevertheless, the relative abundance of arbuscular mycorrhizal fungi was positively correlated to root carbon content, but negatively to the numbers of root forks per root length. Our results suggest that the fine root economics spectrum is important for predicting broader groups of soil microorganisms (i.e. fungi and bacteria), while individual root traits may be more important for predicting soil microbial taxa and functional guilds.

An integrated framework of plant form and function: the belowground perspective

“…(2020) demonstrated that SRL is not positioned on the root conservation gradient but on an independent PC axis related to the ‘collaboration gradient’ that has evolved in concert with symbiosis with mycorrhizal fungi. This novel global conceptualization of belowground trait space has now also been observed in more local and regional studies (Spitzer et al ., 2021; Stock et al ., 2021; Sun et al ., 2021; Sweeney et al ., 2021; Williams et al ., 2021). The key traits along this gradient are mean root diameter (RD) and SRL.…”

Multi‐dimensionality as a path forward in plant‐soil feedback research

“…Most notably, ‘fast’ species with high specific root length (SRL) may be particularly susceptible to fungal pathogens (Bergmann et al., 2016; Cortois et al., 2016). Recent studies have included a larger suite of root traits, to further explore how root anatomy, morphology, chemistry and physiology influence plant interactions with soil microbes and broad groups of soil fauna (Leff et al., 2018; Moreau et al., 2015; Spitzer et al., 2021; Wilschut et al., 2019). However, in most cases root traits only explained a small portion, if any, of the variation in associated soil communities.…”

Effects of Plant Fine Root Functional Traits and Soil Nutrients on the Diversity of Rhizosphere Microbial Communities in Tropical Cloud Forests in a Dry Season

“…For example, Sweeney et al (2021) found that temperate grassland plant functional traits, especially root traits, affect the composition of the rhizosphere fungal community and can be used to predict the fungal community. Similarly, Spitzer et al (2021) found that the spectrum of subarctic tundra meadow plants' fine root economic trait chemical axis is positively correlated with the rhizosphere fungus/bacteria ratio. Although many studies have focused on the relationship between root traits and rhizosphere soil microbes [12,[14][15][16][17][18][19][20], no studies we are aware of have explored these relationships in a high-altitude tropical forest ecosystem.…”

“…The studies of Zhao [23], Glassman [24] and other scholars [25][26][27][28] mentioned above also showed similar results. Plant roots and rhizosphere soil microorganisms are closely connected, and fine roots and their functional traits affect rhizosphere microorganisms through root exudates and litter quality [13]. The function of specific metabolites in root exudates is indicative of the characteristics of the root economic spectrum, which includes the plant root functional traits.…”

“…They are sensitive to the changes in the soil environment and adapt to the environmental changes by changing their shapes and other characteristics [11]. Studies have found that the functional traits of fine roots are significant for predicting soil microbial groups and functional communities [12,13]. For example, Sweeney et al (2021) found that temperate grassland plant functional traits, especially root traits, affect the composition of the rhizosphere fungal community and can be used to predict the fungal community.…”