skip to main content


Title: Traits of soil bacteria predict plant responses to soil moisture
Abstract

Microorganisms can help plants and animals contend with abiotic stressors, but why they provide such benefits remains unclear. Here we investigated byproduct benefits, which occur when traits that increase the fitness of one species provide incidental benefits to another species with no direct cost to the provider. In a greenhouse experiment, microbial traits predicted plant responses to soil moisture such that bacteria with self‐beneficial traits in drought increased plant early growth, size at reproduction, and chlorophyll concentration under drought, while bacteria with self‐beneficial traits in well‐watered environments increased these same plant traits in well‐watered soils. Thus, microbial traits that promote microbial success in different moisture environments also promote plant success in these same environments. Our results demonstrate that byproduct benefits, a concept developed to explain the evolution of cooperation in pairwise mutualisms, can also extend to interactions between plants and nonsymbiotic soil microbes.

 
more » « less
Award ID(s):
2009125 1832042 2022049
NSF-PAR ID:
10400184
Author(s) / Creator(s):
 ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Ecology
Volume:
104
Issue:
2
ISSN:
0012-9658
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Microbes can promote beneficial plant and animal responses to abiotic environments, but the ecological drivers of this benefit remain elusive. Here we investigated byproduct benefits, which occur when traits that increase the fitness of one species provide incidental benefits to another species with no direct cost to the provider species. In experimental mesocosms, microbial traits predicted plant responses to soil moisture such that bacteria with self-beneficial traits in drought increased plant early growth, size at reproduction, and chlorophyll concentration under drought, while bacteria with self-beneficial traits in well-watered environments increased these same plant traits in well-watered environments. Thus, microbial traits that promote microbial success in different soil moisture environments also promote plant success in these same environments. Our results show that the concept of byproduct benefits, originally conceived to explain the evolution of cooperation in pairwise mutualisms, also applies to interactions between plants and non-symbiotic soil microbes. Descriptions of the data can be found in the README_Bolin_Lennon_Lau_2022.txt file. 
    more » « less
  2. While a plant's microbiome can facilitate adaptive phenotypes, the plant's role in selecting for these microbes is unclear. Do plants actively recruit microbes beneficial to their current environment, or are beneficial microbes only an incidental by-product of microbial adaptation? We addressed these questions through a multigeneration greenhouse experiment, selecting for either dry- or wet-adapted soil microbial communities, either with or without plants. After three plant generations, we conducted a full reciprocal transplant of each soil community onto wet- and dry-treated plants. We found that plants generally benefited from soil microbes, and this benefit was greater whenever their current watering conditions matched the microbes' historical watering conditions. Principally, the plant's presence was not necessary in the historical treatments for this environmental matching benefit to emerge. Moreover, we found microbes from droughted soils could better tolerate drought stress. Taken together, these results suggest that the moisture environment selects for microbes that benefit plants under those specific moisture conditions, and that these beneficial properties arise as a by-product of microbial adaptation to the watering environment and not as a co-adapting plant–microbe system. This work highlights that understanding the selective agents on these plant-associated microbes will lead to a better understanding of plant adaptation.

     
    more » « less
  3. Abstract

    Droughts are predicted to become more frequent and intense in many tropical regions, which may cause shifts in plant community composition. Especially in diverse tropical communities, understanding how traits mediate demographic responses to drought can help provide insight into the effects of climate change on these ecosystems. To understand tropical tree responses to reduced soil moisture, we grew seedlings of eight species across an experimental soil moisture gradient at the Luquillo Experimental Forest, Puerto Rico. We quantified survival and growth over an 8‐month period and characterized demographic responses in terms of tolerance to low soil moisture—defined as survival and growth rates under low soil moisture conditions—and sensitivity to variation in soil moisture—defined as more pronounced changes in demographic rates across the observed range of soil moisture. We then compared demographic responses with interspecific variation in a suite of 11 (root, stem, and leaf) functional traits, measured on individuals that survived the experiment. Lower soil moisture was associated with reduced survival and growth but traits mediated species‐specific responses. Species with relatively conservative traits (e.g., high leaf mass per area), had higher survival at low soil moisture whereas species with more extensive root systems were more sensitive to soil moisture, in that they exhibited more pronounced changes in growth across the experimental soil moisture gradient. Our results suggest that increasing drought will favor species with more conservative traits that confer greater survival in low soil moisture conditions.

     
    more » « less
  4. Abstract

    We conducted a research campaign in a neotropical rainforest in Costa Rica throughout the drought phase of an El‐Nino Southern Oscillation event to determine microbial community dynamics and soil C fluxes. Our study included nests of the leafcutter antAtta cephalotes, as soil disturbances made by these ecosystem engineers may influence microbial drought response. Drought decreased the diversity of microbes and the abundance of core microbiome taxa, including Verrucomicrobial bacteria and Sordariomycete fungi. Despite initial responses of decreasing diversity and altered composition, 6 months post‐drought the microbiomes were similar to pre‐drought conditions, demonstrating the resilience of soil microbial communities to drought events.A. cephalotesnests altered fungal composition in the surrounding soil, and reduced both fungal mortality and growth of Acidobacteria post‐drought. Drought increased CH4consumption in soils due to lower soil moisture, andA. cephalotesnests decrease the variability of CH4emissions in some soil types. CH4emissions were tracked by the abundance of methanotrophic bacteria and fungal composition. These results characterize the microbiome of tropical soils across both time and space during drought and provide evidence for the importance of leafcutter ant nests in shaping soil microbiomes and enhancing microbial resilience during climatic perturbations.

     
    more » « less
  5. Abstract

    Climate change alters mean global surface temperatures, precipitation regimes, and atmospheric moisture. Resultant drought affects the composition and diversity of terrestrial ecosystems worldwide. To date, there have been no assessments of the combined impacts of reduced precipitation and atmospheric drying on functional trait distributions of any species in an outdoor experiment. Here, we examined whether soil and atmospheric drought affected the functional traits of a focal grass species (Poa secunda) growing in monoculture and eight‐species grass communities in outdoor mesocosms. We focused on specific leaf area (SLA), leaf area, stomatal density, root:shoot ratio, and fine root:coarse root ratio responses. Leaf area and overall growth were reduced with soil drying. Root:shoot ratio only increased forP. secundagrowing in monoculture under combined atmospheric and soil drought. Plant energy allocation strategy (measured using principal components) differed whenP. secundawas grown in combined soil and atmospheric drought conditions compared with soil drought alone. Given a lack of outdoor manipulations of this kind, our results emphasize the importance of atmospheric drying on functional trait responses more broadly. We suggest that drought methods focused purely on soil water inputs may be imprecisely predicting drought effects on other terrestrial organisms as well (other plants, arthropods, and higher trophic levels).

     
    more » « less