Biology subjects

Lash, E.

Publications and source records attributed to Lash, E..

3 recordsLinked to original sources

bioRxiv2023

Host-microbiome mutualisms emerge from community interactions among microbes

Microbiomes often benefit plants, conferring resistance to pathogens, improving stress tolerance, or promoting plant growth. As potential plant mutualists, however, microbiomes are not a single organism but a community of species with complex interactions among microbial taxa and between microbes and their shared host. The nature of ecological interactions among microbes in the microbiome can have important consequences for the net effects of microbiomes on hosts. Here, we compared the effects of individual microbial strains and 10-strain synthetic communities on microbial productivity and host growth using the common duckweed Lemna minor and a synthetic, simplified version of its native microbiome. Except for Pseudomonas protegens, which was a mutualist when tested alone, all of the single strains we tested were commensals on hosts, benefiting from plant presence but not increasing host growth relative to uninoculated controls. However, 10-strain synthetic microbial communities increased both microbial productivity and duckweed growth more than the average single-strain inoculation and uninoculated controls, meaning that host-microbiome mutualisms can emerge from community interactions among microbes on hosts. The effects of community inoculation were sub-additive, suggesting at least some competition among microbes in the duckweed microbiome. We also investigated the relationship between L. minor fitness and that of its microbes, providing some of the first empirical estimates of broad fitness alignment between plants and members of their microbiomes; hosts grew faster with more productive microbes or microbiomes.

ecology↗

bioRxiv2021

A functionally divergent intrinsically disordered region underlying the conservation of stochastic signaling

Stochastic signaling dynamics expand living cells information processing capabilities. An increasing number of studies report that regulators encode information in their pulsatile dynamics. The evolutionary mechanisms that lead to complex signaling dynamics remain uncharacterized, perhaps because key interactions of signaling proteins are encoded in intrinsically disordered regions (IDRs), whose evolution is difficult to analyze. Here we focused on the stochastic pulsing dynamics of Crz1, a transcription factor in fungi downstream of the widely conserved calcium signaling pathway. We find that Crz1 IDRs from anciently diverged fungi can all respond transiently to calcium stress; however, only Crz1 IDRs from the Saccharomyces clade support pulsatility, encode extra information, and rescue fitness, while the Crz1 IDRs from distantly related fungi do none of the three. On the other hand, we find that Crz1 pulsing is conserved in the distantly related fungi, consistent with the evolutionary model of stabilizing selection. Further, we show that a calcineurin docking site in a specific part of the IDRs appears to be sufficient for pulsing and show evidence for a beneficial increase in the relative calcineurin affinity of this docking site. We propose that evolutionary flexibility of functionally divergent IDRs underlies the conservation of stochastic signaling by stabilizing selection.

evolutionary biology↗

bioRxiv2018

Mutualism outcome across plant populations, microbes, and environments in the duckweed Lemna minor

The picture emerging from the rapidly growing literature on host-associated micro-biota is that host traits and fitness often depend on complex and interactive effects of host genotype, microbial interactions, and abiotic environment. However, testing these main and interactive effects typically requires large, multi-factorial experiments and thus remains challenging in many systems. Furthermore, most studies of plant microbiomes focus on terrestrial hosts and microbes. Aquatic habitats may confer unique properties to plant micriobiomes. We grew different populations of duck-weed (Lemna minor), a floating aquatic plant of increasing popularity in freshwater phytoremediation, in three microbial treatments (adding no, \"home\", or \"away\" microbes) at two levels of zinc, a common water contaminant in urban areas. Thus, we simultaneously manipulated plant source population, microbial community, and the abiotic environment, and measured both plant and microbial performance as well as plant traits. Although we found little evidence of interactive effects, we found strong main effects of plant source, microbial treatment, and zinc on both duckweed and microbial growth, with significant variation among both duckweed and microbial communities. Despite strong growth alignment between duckweed and microbes, zinc consistently decreased plant growth, but increased microbial growth. Furthermore, as in recent studies of terrestrial plants, microbial interactions altered a duckweed phenotype (frond aggregation). Our results suggest that the duckweed source population, its associated microbiome, and the contaminant environment may all need to be considered in real-world phytoremediation efforts. Lastly, we propose that duckweed microbes offer a robust experimental system for study of host-microbiota interactions under a range of environmental stresses.

ecology↗