Endophytes shape the legacy left by the above‐ and below‐ground litter of the host affecting the establishment of a legume

Abstract

1. Plant litter is a key component of plant-soil feedback (PSF), given its strong potential impacts on plant establishment and growth, through chemical and physical pathways. Although PSF of the layer of dead plant material on the soil surface (above-ground litter) has been widely studied, little is known about the role of dead roots (below-ground litter) and the impact of plant symbionts on host litter legacy.2. Here, we examined whether the fungal endophyte Epichloë occultans changed the effects of above-and below-ground litter of Lolium multiflorum plants on the establishment of Trifolium repens. We hypothesized that both types of litter deposited by the grass-endophyte symbiosis reduce the establishment of the legume due to the release of allelopathic compounds during the decomposition and leaching processes.3. To test this, we performed two experiments with different quantities of litter produced by plants of the same grass population, with high and low levels of endophyte infection (E+ and E−). Seeds of T. repens were exposed to the above-ground litter with or without the addition of below-ground litter, or to their leachates, to separate the physical and chemical pathways. 4. We found that the treatments with the combination of the above-and belowground litter produced by E+ plants increased the germination speed and seedling emergence of T. repens by 56% compared with both types of litter produced by E− plants. A similar effect was also observed with only the above-ground litter.However, the below-ground litter of E+ plants reduced the germination speed, seedling emergence by 76% and establishment of T. repens by 73% compared with the below-ground litter of E− plants. Besides, the below-ground litter had positive effects on the root colonization by arbuscular mycorrhizal fungi and reduced the root nodulation of T. repens. The quantity of litter did not affect any of these responses. 5. Our results suggest that these litter legacy effects could be due to the release of endophyte-induced secondary metabolites, such as phenolic and flavonoid compounds. Changes in host plant litter inputs may have consequences for the | 2871Functional Ecology MINÁS et al.

Realistic time-lags and litter dynamics alter predictions of plant–soil feedback across generations

“…Yet during naturally occurring time lags of discrete growing seasons, the microbial community originally conditioned by plants may shift due to stochastic drift or biotic interactions between microbes. Moreover, the presence of litter can introduce microbes from other plant parts into the soil (Whitaker et al ., 2017, Fanin et al ., 2021) and the decomposition of litter can change the soil abiotic environment, thereby altering the soil microbial community (Veen et al ., 2021, Minás et al ., 2021). Thus, the microbial community encountered by a responding plant after the time delay may no longer resemble that of the original conditioning (Fig.…”

“…Another aspect of the soil conditioning process that is largely overlooked in two-phase plant– soil feedback experiments is that, in nature, the soil microbial community is shaped not only by the active conditioning effects of plants as they grow but also by the dead tissue (i.e., litter) that plants deposit onto the soil. Specifically, recent literature has shown that plant litter of different species can influence microbial communities by introducing phyllosphere microbes to the soil (Whitaker et al ., 2017, Fanin et al ., 2021, Minás et al ., 2021) and by releasing chemicals and nutrients that affect soil microbial community assembly (Veen et al ., 2021). These litter-induced changes in the microbial community can subsequently result in different plant–soil feedback on the responding plants (Veen et al ., 2019, Aldorfová et al ., 2022).…”

Pathways of glyphosate effects on litter decomposition in grasslands

“…Other studies suggest that changes in leaf litter chemistry (i.e. phenolic content), in the microenvironment and/or in the decomposer community may explain the differences (Lemons et al, 2005; Minás et al, 2021; Omacini et al, 2004).…”

“…Interestingly, root decomposition of the endophytic plants was similar to that of the non‐endophytic plants (Figure 3d), which is consistent with the non‐detectable changes in litter quality (Table 1). However, a recent study shows that leachates of root litter of endophytic L. multiflorum have higher content of flavonoids with the potential to reduce the establishment of legume plants (Lemons et al, 2005, Minás et al, 2021, Omacini et al, 2004). Thus, even though the fungal endophyte may not affect decomposition directly by root quality, it can have effects in the long term by reducing the abundance of highly decomposable legumes.…”