Surface Coating-Modulated Phytotoxic Responses of Silver Nanoparticles in Plants and Freshwater Green Algae

Silver nanoparticles (AgNPs) have been implemented in a wide range of commercial products, resulting in their unregulated release into aquatic as well as terrestrial systems. This raises concerns over their impending environmental effects. Once released into the environment, they are prone to various transformation processes that modify their reactivity. In order to increase AgNP stability, different stabilizing coatings are applied during their synthesis. However, coating agents determine particle size and shape and influence their solubility, reactivity, and overall stability as well as their behavior and transformations in the biological medium. In this review, we attempt to give an overview on how the employment of different stabilizing coatings can modulate AgNP-induced phytotoxicity with respect to growth, physiology, and gene and protein expression in terrestrial and aquatic plants and freshwater algae.

Study of a green algae Lobochlamys segnis Strain-019 from peatland

Characterization of a green algae Lobochlamys segnis strain 019 using morphological dan phylogenetic study were determined. In this study, contribution of natural nutrients will be evaluated by culturing this strain using Sphagnum peat soil extract in comparing to that of a commercial media for freshwater algae. Based on morphological study, L.segnis strain 019 is a unicellular biflagellate. This Chlamydomonas-like algae possessed a cup shaped to lateral chloroplast with central pyrenoid and a low indistinct papilla. Molecular phylogenetic analyses based on 18 S rDNA indicated that this strain is a member of Lobochlamys subclade, and formed a robust clade (PP = 1.0, BP = 99%) with Oogamochlamys. Strain 019 formed a buble-like colonies covered by mucilage material under agar culture condition. In this study, a moderate acidic condition pH 4.0 was applied for both media due to liquid medium of Sphagnum peat soil extract detected in this pH value. The biomass production, lipid production and fatty acid composition using peat soil extract and AF-6 media are evaluated and discussed.

Integrating transcriptomes to investigate genes associated with adaptation to aquatic environments, and assess phylogenetic conflict and whole-genome duplications in Alismatales

Land plants first evolved from freshwater algae, and flowering plants returned to water as early as the Cretaceous and multiple times beyond. Alismatales is the largest clade of aquatic angiosperms including all marine angiosperms, as well as terrestrial plants. We used Alismatales to explore plant adaptation to aquatic environments by including 95 samples (89 Alismatales species) covering four genomes and 91 transcriptomes (59 generated in this study). To provide a basis for investigating adaptation, we assessed phylogenetic conflict and whole-genome duplication (WGD) events in Alismatales. We recovered a relationship for the three main clades in Alismatales as ((Tofieldiaceae, Araceae), core Alismatids). There is phylogenetic conflict among the backbone of the three main clades that could be due to incomplete lineage sorting and introgression. We identified 18 putative WGD events. One of them had occurred at the most recent common ancestor of core Alismatids, and four occurred at seagrass lineages. Other events are distributed in terrestrial, emergent, and submersed life-forms and seagrasses across Alismatales. We also found that lineage and life-form were each important for different evolutionary patterns for the genes related to freshwater/marine adaptation. For example, some light or ethylene-related genes were lost in the seagrass Zosteraceae, but present in other seagrasses and freshwater species. Stomata-related genes were lost in both submersed freshwater species and seagrasses. Nicotianamine synthase genes, which are important in iron intake, expanded in both submersed freshwater species and seagrasses. Our results advance the understanding of the adaptation to aquatic environments, phylogeny, and whole-genome duplication of Alismatales.

A multifaceted ecological assessment reveals the invasion of the freshwater red macroalga Montagnia macrospora (Batrachospermales, Rhodophyta) in Taiwan

Invasive freshwater macroalgae are rarely described. Recently, a freshwater red alga, Montagnia macrospora, was introduced from South America to East Asia via the global aquarium trade. The earliest occurrence record of this alga in Taiwan is dated 2005. To determine whether M. macrospora has become an invasive species in Taiwan and to understand its traits that facilitated its invasion, we took a total-evidence approach that combines examination of ecological background and population genetic analysis. Our island-wide survey showed that M. macrospora alga was widespread in the field across Taiwan, where the climate greatly differs from that of South America. Our population genetic analysis revealed that the cox2-3 sequences of all the specimens of M. macrospora from Taiwan were identical, consistent with the hypothesis that the alga expanded through asexual reproduction. Moreover, during our long-term ecological assessments and field surveys, we observed that M. macrospora is an ecological generalist that can self-sustain for a decade and bloom. Taken together, our data suggest that M. macrospora has successfully invaded the freshwater ecosystems in Taiwan due to its ability to disperse asexually and to grow under broad environmental conditions. We hope that our study brings attention to invasive freshwater algae, which have been overlooked in conservation planning and management.