More Like this

1. Two duckweed species exhibit variable tolerance to microcystin-LR exposure across genotypic lineages

   https://doi.org/10.1016/j.hal.2023.102548  

   Rzodkiewicz, Lacey D.; Turcotte, Martin M. (January 2024, Harmful Algae)

   Cyanotoxins produced by harmful cyanobacteria blooms can damage freshwater ecosystems and threaten human health. Floating macrophytes may be used as a means of biocontrol by limiting light and resources available to cyanobacteria. However, genetic variation in macrophyte sensitivity to cyanotoxins could influence their suit- ability as biocontrol agents. We investigated the influence of such intraspecific variation on the response of two rapidly growing duckweed species, Lemna minor and Spirodela polyrhiza, often used in nutrient and metal bioremediation. We assessed two biomarkers related to productivity (biomass and chlorophyll A production) and two related to fitness measures (population size and growth rate). Fifteen genetic lineages of each species were grown in media containing common cyanotoxin microcystin-LR at ecologically relevant concentrations or control media for a period of twelve days. Genotype identity had a strong impact on all biomarker responses. Microcystin concentration slightly increased the final population sizes of both macrophyte species with a marginal effect on growth rate of L. minor and the chlorophyll A production of S. polyrhiza, but overall these species were very tolerant of microcystin. The strong tolerance supports the potential use of these plants as bioremediators of cyanobacterial blooms. However, differential impact of microcystin exposure discovered in single lineage models among genotypes indicates a potential for cyanotoxins to act as selective forces, necessitating attention to genotype selection for bioremediation. 

   more » « less
2. Growth and Nutritional Quality of Lemnaceae Viewed Comparatively in an Ecological and Evolutionary Context

   https://doi.org/10.3390/plants11020145  

   Demmig-Adams, Barbara; López-Pozo, Marina; Polutchko, Stephanie K.; Fourounjian, Paul; Stewart, Jared J.; Zenir, Madeleine C.; Adams, William W. (January 2022, Plants)

   This review focuses on recently characterized traits of the aquatic floating plant Lemna with an emphasis on its capacity to combine rapid growth with the accumulation of high levels of the essential human micronutrient zeaxanthin due to an unusual pigment composition not seen in other fast-growing plants. In addition, Lemna’s response to elevated CO2 was evaluated in the context of the source–sink balance between plant sugar production and consumption. These and other traits of Lemnaceae are compared with those of other floating aquatic plants as well as terrestrial plants adapted to different environments. It was concluded that the unique features of aquatic plants reflect adaptations to the freshwater environment, including rapid growth, high productivity, and exceptionally strong accumulation of high-quality vegetative storage protein and human antioxidant micronutrients. It was further concluded that the insensitivity of growth rate to environmental conditions and plant source–sink imbalance may allow duckweeds to take advantage of elevated atmospheric CO2 levels via particularly strong stimulation of biomass production and only minor declines in the growth of new tissue. It is proposed that declines in nutritional quality under elevated CO2 (due to regulatory adjustments in photosynthetic metabolism) may be mitigated by plant–microbe interaction, for which duckweeds have a high propensity. 

   more » « less
3. Environment and Host Genetics Influence the Biogeography of Plant Microbiome Structure

   https://doi.org/10.1007/s00248-023-02288-6  

   Wei, Na; Tan, Jiaqi (August 2023, Microbial Ecology)

   To understand how microbiota influence plant populations in nature, it is important to examine the biogeographic distribution of plant-associated microbiomes and the underlying mechanisms. However, we currently lack a fundamental understanding of the biogeography of plant microbiomes across populations and the environmental and host genetic factors that shape their distribution. Leveraging the broad distribution and extensive genetic variation in duckweeds (the Lemna species complex), we identified key factors that governed plant microbiome diversity and compositional variation geographically. In line with the microbial biogeography of free-living microbiomes, we observed higher bacterial richness in temperate regions relative to lower latitudes in duckweed microbiomes (with 10% higher in temperate populations). Our analyses revealed that higher temperature and sodium concentration in aquatic environments showed a negative impact on duckweed bacterial richness, whereas temperature, precipitation, pH, and concentrations of phosphorus and calcium, along with duckweed genetic variation, influenced the biogeographic variation of duckweed bacterial community composition. Analyses of plant microbiome assembly processes further revealed that niche-based selection played an important role (26%) in driving the biogeographic variation of duckweed bacterial communities, alongside the contributions of dispersal limitation (33%) and drift (39%). These findings add significantly to our understanding of host-associated microbial biogeography and provide important insights for predicting plant microbiome vulnerability and resilience under changing climates and intensifying anthropogenic activities. 

   more » « less
4. Differences in drought avoidance rather than differences in the fast versus slow growth spectrum explain distributions of two Asclepias species

   https://doi.org/10.1111/ppl.70034  

   Matzner, Steven_L; Konz, Emily_R; Marts, Samantha_A; Eversman, Haley_M; Kasuske, Kyla_M; Atkins, Trinity_L; Acharya, Sneha; Matuck, Lara_C; Derynck, Lillian_M; Kreutzmann, Sydney; et al (December 2024, Physiologia Plantarum)

   Abstract Understanding factors that determine a species' geographical range is crucial for predicting climate‐induced range shifts. Two milkweed species,Asclepias syriacaandAsclepias speciosa, have overlapping ranges along a moisture gradient in North America and are primary food sources for endangered monarch caterpillars. With decreasing moisture, long‐lived species often exhibit slower growth and greater drought tolerance, while many annual species exhibit faster growth strategies. Using this fast‐slow framework, we assessed whether traits of these two sister species differ along a fast‐slow growth continuum and could explain their distributions. We measured leaf and root functional traits in common gardens and greenhouse experiments. In key measures indicative of drought tolerance (e.g., growth, transpiration, and water potentials), the species were nearly identical. Contrary to expectations,A. speciosadid not exhibit greater drought tolerance, raising the question of how it survives in the more arid west. A reciprocal transplant study showed selection againstA. syriacain the western garden and thatA. speciosawas better able to avoid seedling mortality. Focusing on seedling establishment, we found thatA. speciosaexhibited faster deep‐root development and a narrow leaf phenotype associated with slower wilting and delayed drought‐induced mortality. Rather than differences on the fast‐slow growth spectrum, our results indicate thatA. speciosaavoids drought through faster deep‐root growth and a slower wilting phenotype. Our study suggests thatA. syriaca'srange is limited by its drought tolerance, while A. speciosaemploys a number of drought avoidance strategies to survive in more arid environments. 

   more » « less
5. A review of using duckweed (Lemnaceae) in fish feeds

   https://doi.org/10.1111/raq.12892  

   Minich, Jeremiah J; Michael, Todd P (June 2024, Reviews in Aquaculture)

   Abstract One of the primary sustainability challenges in aquaculture is replacing fish meal with plant‐based ingredients in aquafeeds. Plants are not optimal due to low protein content and antinutritional factors which can cause gut dysbiosis. Duckweed (Lemnaceae) is a family of aquatic plants with high protein content and has been used successfully for various types of animal feeds. In this systematic review and meta‐analysis of 58 papers, we summarize the extent by which duckweed has been used in fish production including the species of fish tested, the grow‐out stage of fish, and method of application. Duckweed studies spanned a total of 18 species of fish (16 freshwater and two marine) that collectively are valued at 263 billion USD annually, and comprise 28% of total aquaculture production by mass. The average experiment length was 72 days (SD 42), primarily at the fingerling life stage. Duckweed was fed to the fish through live grazing, dried, and pelleted forms with 20% inclusion as the most common formulation. TheLemnaspp., dominated byL.minor,L.gibba, and unknownLemnaspecies, were the most commonly used for feeds.Spirodela polyrhizawas the second most common. Duckweed inclusion levels between 15% and 30% were associated with positive outcomes on fish growth and feed conversion ratio without any negative impact on survival rates. Most duckweed species, especially fromWollfiellahave not been tested as a fish feed but should be explored whereas most studies focused on freshwater fishes rather than marine. 

   more » « less