Resistance and resilience of root fungal communities to water limitation in a temperate agroecosystem

Abstract

Understanding crop resilience to environmental stress is critical in predicting the consequences of global climate change for agricultural systems worldwide, but to date studies addressing crop resiliency have focused primarily on plant physiological and molecular responses. Arbuscular mycorrhizal fungi (AMF) form mutualisms with many crop species, and these relationships are key in mitigating the effects of abiotic stress in many agricultural systems. However, to date there is little research examining whether (1) fungal community structure in agroecosystems is resistant to changing environmental conditions, specifically water limitation and (2) resilience of fungal community structure is moderated by agricultural management systems, namely the integration of trees into cropping systems. Here, we address these uncertainties through a rainfall reduction field experiment that manipulated short‐term water availability in a soybean‐based (Glycine max L. Merr.) agroforest in Southern Ontario, Canada. We employed terminal restriction fragment length polymorphism analysis to determine the molecular diversity of both general fungal and AMF communities in soybean roots under no stress, stress (rainfall shelters added), and poststress (rainfall shelters removed). We found that general fungal and AMF communities sampled from soybean roots were resistant to rainfall reduction in a monoculture, but not in an agroforest. While AMF communities were unchanged after stress removal, general fungal communities were significantly different poststress in the agroforest, indicating a capacity for resiliency. Our study indicates that generalist fungi and AMF are responsive to changes in environmental conditions and that agroecosystem management plays a key role in the resistance and resilience of fungal communities to water limitation.

Effects of Short- and Long-Term Variation in Resource Conditions on Soil Fungal Communities and Plant Responses to Soil Biota

“…The clear changes in AMF and pathogen communities in soil inocula experiencing drought indicate that soil moisture, or moisture-mediated shifts in either host plant status or nutrient availability can strongly influence fungal communities. Our results generally agree with previous studies that have shown shifts in fungal communities along precipitation gradients (Kivlin et al, 2011 ; Tedersoo et al, 2014 ; Zhang et al, 2016 ) and where soil moisture has been experimentally altered (Furze et al, 2017 ; Kaisermann et al, 2017 ; Meisner et al, 2018 ; Schmidt et al, 2018 ; She et al, 2018 ). These changes in composition may or may not result in altered fungal richness, which sometimes declines (Toberman et al, 2008 ; Gehring et al, 2017 ), show no difference (Schmidt et al, 2018 ; She et al, 2018 ), or even increase (Hawkes et al, 2011 ) with drought.…”

Nutrient acquisition strategies in agroforestry systems

“…In TBI systems, water availability controlled competition between Juglans nigra and maize for mineralized N (Jose et al 2000), while fine root dynamics may be largely controlled by climate, as suggested by the differential root elongation rates of J. nigra (Mohamed et al 2018). Under sub-optimal climatic conditions, we know that key microbial communities were more resilient in a temperate TBI system (Furze et al 2017), a Mediterranean agroforestry system (Guillot et al 2019), and a Zanthoxylum bungeanumbased intercropped system (Sun et al 2016). Relationships between root trait expression and microbial communities involved in soil C and N dynamics were reported under droughty conditions (De Vries et al 2016), but much work is needed to elucidate the interactive function of microbial-plant nutrient acquisition patterns in agroforestry systems to achieve resilience under environmental change.…”

Legacy Effects Overshadow Tree Diversity Effects on Soil Fungal Communities in Oil Palm-Enrichment Plantations

“…The root-associated microbiome often differs significantly from the surrounding soil communities, as a consequence of host plant properties [100][101][102]. Agroforestry systems can promote diversity, alter composition, and improve the resilience of root-associated fungal communities [103][104][105], and those effects may generate feedback on the surrounding soil after long-term establishment of tree enrichment. Studying further succession, as well as analysis of the root-associated communities of planted tree species, could help to predict future effects of tree diversity enrichment on the soil microbiome in monoculture plantations.…”