Routes to Roots: Direct Evidence of Water Transport by Arbuscular Mycorrhizal Fungi to Host Plants

Kakouridis, Anne; Hagen, John A.; Kan, Megan; Mambelli, Stefania; Feldman, Lewis J.; Herman, Donald J.; Pett‐Ridge, Jennifer; Firestone, Mary K.

doi:10.1101/2020.09.21.305409

Cited by 16 publications

(16 citation statements)

References 33 publications

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“…Sieverding (1989) discovered that plant root length is positively correlated with the detected soil volume of the The Role of Arbuscular Mycorrhiza Fungi in Drought Tolerance in Legume Crops: A Review plant body. Data showed that AMF mycelium transported about 46.2% of the water into the plant (Kakouridis et al, 2020). A similar study showed that when plants suffered drought, AMF hyphae was able to provide at least 1/5 of the total water (McCorkle et al, 2011).…”

Section: Mechanism Of Amf-conferred Water Management In Legumesmentioning

confidence: 80%

The Role of Arbuscular Mycorrhiza Fungi in Drought Tolerance in Legume Crops: A Review

Pandey

et al. 2022

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Legumes are low-cost but high-yielding crops, which are rich in dietary proteins, vitamins and minerals. Known as mycorrhizal plants, legumes are widely used as model organisms to explore the plant-microbe interactions, especially the symbiotic relationship between plants and rhizosphere microorganisms. Arbuscular mycorrhizal fungi (AMF), an important class of plant-associated microbes, can regulate many physiological and molecular responses of plants. To date, AMF has been commonly used as a bio-fertilizer, whose inoculation to host plants can confer tolerance to different abiotic stresses such as drought, salinity, heat and heavy metals. This review provides an overview of the responses of legumes to drought stress (DS), a summary of the mechanism of AMF-legume symbiosis and its effect on host plant drought tolerance, which taken together reveals the significance of this symbiosis in agriculture. The presented rich information will help understand how host plants benefit from AMF to increase drought tolerance while finetuning their metabolic pathways. The potential and importance of AMF as one of the most effective and environmental-friendly management approaches for enhancing legume crop productivity against DS is highlighted.

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Section: Mechanism Of Amf-conferred Water Management In Legumesmentioning

confidence: 80%

The Role of Arbuscular Mycorrhiza Fungi in Drought Tolerance in Legume Crops: A Review

Pandey

et al. 2022

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“…Bacteria grow quickly and are more sensitive to drought and other stresses than fungi [53][54][55][56][57][58] . Furthermore, fungi are able to create large hyphal networks that facilitate nutrient and water transfer over long distances, and indirectly benefit plants by exploring water-filled soil pores not accessible to plant roots 57,59,60 .…”

Section: Discussionmentioning

confidence: 99%

Intensive management disrupts belowground multi-trophic resources transfers in response to drought

Chomel

Lavallee

Segura

et al. 2022

Preprint

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Modification of soil food webs by historical land management may alter the response of ecosystem processes to climate extremes, but empirical support for this is limited and the mechanisms involved remain unclear. Here, we quantified how historical grassland management modifies transfers of recent photosynthate and soil nitrogen through plants and soil food web in response to drought, using in situ 13C and 15N pulse-labelling in paired intensively and extensively managed fields. We show that intensive management decreased plant carbon capture, its transfer through key components of food webs and soil respiration compared to extensive management. Drought only affected carbon transfer pathways in intensively managed grasslands, by increasing plant C assimilation but decreasing its transfer to plant roots, bacteria and Collembola. However, drought lowered the reduction of added nitrate to nitrous oxide in extensively managed grassland only. Our findings indicate that intensive management disrupts fluxes of recent photosynthates belowground, which impaired resistance of this process in response to drought. By contrast, extensive grassland management provides a greater potential to buffer impacts to drought by promoting the transfer of recent photosynthate belowground. Our work highlights that capture and rapid transfer of photosynthate through multitrophic networks is a key process for maintaining grassland resilience to drought.

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“…Furthermore, we observed a slight decline in belowground 13 C content between 0 days and 4 weeks following the 13 C labeling (Figure 1), which is likely from root and microbial respiration. These findings indicate that as plants continue to grow, recently-fixed photosynthate was rapidly translocated within the plant and released into the soil as labile C compounds exuded by roots (and perhaps also by associated arbuscular mycorrhizal fungi (AMF) (Kakouridis et al, 2021)). Almost just as rapidly, these labile exudates are metabolized by the active rhizosphere microbial communities (Waldrop & Firestone, 2006).…”

Section: Ecosystem 13 C Incorporationmentioning

confidence: 98%

“…C-rich fungal hyphae, bacterial EPS, and plant mucilage promote soil aggregation both as physical structuring agents as well as major contributors to aggregate-associated soil carbon (Six et al 2004). OLF material has been found to be largely dominated by fine root fragments and fungal hyphae (Kakouridis et al, 2021). The intermediate OLF C:N ratio we measured (between that of FLF and HF) suggests that microbial constituents and aggregation mechanisms such as fungal hyphae and bacterial EPS may have contributed to OLF formation in our samples, although extensive microbial processing of OLF material is likely limited due to physical protection mechanisms.…”

Section: Soil Density Fractionsmentioning

confidence: 99%

“…C recovered from Spring18-harvested soil likely represent mostly rhizodeposits and labile carbon substrates exuded by roots and possibly consumed by root-associated bacteria and fungi as well as AMF-mediated carbon flow from 13 CO2-labeled plants (Kakouridis et al, 2021). By our Fall18 sampling, which occurred at the end of the summer dry period, much of the 13 C in FLF would have been composed of senesced/dead 13 CO2-labeled root detritus; we assume that most of the 13 C in the HF and OLF was root-derived (Jackson et al, 2017).…”

Section: Soil Density Fractionsmentioning

confidence: 99%

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Belowground allocation and dynamics of recently fixed plant carbon in a California annual grassland soil

Fossum

Estera-Molina

Yuan

et al. 2021

Preprint

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Plant roots and the organisms that surround them are a primary source for stabilized organic C, particularly in grassland soils, which have a large capacity to store organic carbon belowground. To quantify the flow and fate of plant fixed carbon (C) in a Northern California annual grassland, we tracked plant carbon from a five-day 13CO2 pulse field labeling for the following two years. Soil and plant samples were collected immediately after the pulse labeling, and again at three days, four weeks, six months, one year, and two years. Soil organic matter was fractionated using a sodium polytungstate density gradient to separate the free-light fraction (FLF), occluded-light fraction (OLF), and heavy fraction (HF). Using isotope ratio mass spectrometry, we measured 13C enrichment and total C content for plant shoots, roots, soil, soil dissolved organic carbon (DOC), and the FLF, OLF, and HF. The HF was further analyzed by solid state 13C NMR spectroscopy. At the end of the labeling period, the largest amount of 13C was recovered in plant shoots (60%), but a substantial amount (40%) was already found belowground in roots, soil, and soil DOC. Density fractionation of 4-week soil samples (from which living roots were removed) indicated that the highest isotope enrichment was in the mineral-rich heavy fraction, with similar enrichment of the FLF and OLF. At the 6-month sampling, after the dry summer period during which plants senesced and died, the amount of label in the FLF increased such that it was equal to that in the HF. By the 1-year sampling, 13C in the FLF had declined substantially and continued to decline by the 2-year sampling. 13C recovery in the OLF and HF, however, was qualitatively stable between sampling times. By the end of the 2-year experiment, 69% of remaining label was in the HF, 18% in the FLF and 13% in the OLF. While the total 13C content of the HF did not change significantly from the 4-week to the 2-year sample time, 13C NMR spectroscopic analysis of spring HF samples from 2018, 2019, and 2020 suggests that the relative proportion of aliphatic/alkyl functional groups declined in the newly formed SOC over the 2-year period. Simultaneously, aromatic and carbonyl functional groups increased, and the proportion of carbohydrate groups remained relatively constant. In summary, our results indicate that initial associations between minerals and root-derived organic matter are significant and form rapidly; by 4 weeks, a substantial amount (17%) of the total plant-derived 13C had become associated with the heavy fraction (HF) of soil. While the majority of annual C input cycles rapidly (<2-year timescale), a sizeable proportion (~12% of the original inputs) persisted for 2 years.

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Routes to Roots: Direct Evidence of Water Transport by Arbuscular Mycorrhizal Fungi to Host Plants

Cited by 16 publications

References 33 publications

The Role of Arbuscular Mycorrhiza Fungi in Drought Tolerance in Legume Crops: A Review

The Role of Arbuscular Mycorrhiza Fungi in Drought Tolerance in Legume Crops: A Review

Intensive management disrupts belowground multi-trophic resources transfers in response to drought

Belowground allocation and dynamics of recently fixed plant carbon in a California annual grassland soil

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