Evolution and Stress Responses of CLO Genes and Potential Function of the GhCLO06 Gene in Salt Resistance of Cotton

The caleosin (CLO) protein family displays calcium-binding properties and plays an important role in the abiotic stress response. Here, a total of 107 CLO genes were identified in 15 plant species, while no CLO genes were detected in two green algal species. Evolutionary analysis revealed that the CLO gene family may have evolved mainly in terrestrial plants and that biological functional differentiation between species and functional expansion within species have occurred. Of these, 56 CLO genes were identified in four cotton species. Collinearity analysis showed that CLO gene family expansion mainly occurred through segmental duplication and whole-genome duplication in cotton. Sequence alignment and phylogenetic analysis showed that the CLO proteins of the four cotton species were mainly divided into two types: H-caleosins (class I) and L-caleosins (class II). Cis-acting element analysis and quantitative RT–PCR (qRT–PCR) suggested that GhCLOs might be regulated by abscisic acid (ABA) and methyl jasmonate (MeJA). Moreover, transcriptome data and qRT–PCR results revealed that GhCLO genes responded to salt and drought stresses. Under salt stress, gene-silenced plants (TRV: GhCLO06) showed obvious yellowing and wilting, higher malondialdehyde (MDA) content accumulation, and significantly lower activities of superoxide dismutase (SOD) and peroxidase (POD), indicating that GhCLO06 plays a positive regulatory role in cotton salt tolerance. In gene-silenced plants (TRV: GhCLO06), ABA-related genes (GhABF2, GhABI5, and GhNAC4) were significantly upregulated after salt stress, suggesting that the regulation of salt tolerance may be related to the ABA signaling pathway. This research provides an important reference for further understanding and analyzing the molecular regulatory mechanism of CLOs for salt tolerance.

Metagenomes of Lichens Solorina crocea and Peltigera canina

Lichen genomes are usually considered genomes of separately cultured mycobiont and photobiont. Analysis of lichen metagenomes can give important information on specific lichen-associated microorganisms that can affect lichen metabolism. Here, we report a metagenome of peltigeralean lichens, containing cyanobacterial ( Peltigera canina ) and cyanobacterial/green algal ( Solorina crocea ) partners.

Comparative transcriptomics reveals the molecular toolkit used by an algivorous protist for cell wall perforation

Microbial eukaryotes display a stunning diversity of feeding strategies, ranging from generalist predators to highly specialised parasites. The unicellular protoplast feeders represent a fascinating mechanistic intermediate, as they penetrate other eukaryotic cells (algae, fungi) like some parasites, but then devour their cell contents by phagocytosis. Besides prey recognition and attachment, this complex behaviour involves the local, pre-phagocytotic dissolution of the prey cell wall, which results in well-defined perforations of species-specific size and structure. Yet, the molecular processes that enable protoplast feeders to overcome cell walls of diverse biochemical composition remain unknown. We used the flagellate Orciraptor agilis (Viridiraptoridae, Rhizaria) as a model protoplast feeder, and applied differential gene expression analysis to examine its penetration of green algal cell walls. Besides distinct expression changes that reflect major cellular processes (e.g. locomotion, cell division), we found lytic carbohydrate-active enzymes that are highly expressed and upregulated during the attack on the alga. A putative endocellulase (family GH5_5) with a secretion signal is most prominent, and a potential key factor for cell wall dissolution. Other candidate enzymes (e.g. lytic polysaccharide monooxygenases) belong to families that are largely uncharacterised, emphasising the potential of non-fungal micro-eukaryotes for enzyme exploration. Unexpectedly, we discovered various chitin-related factors that point to an unknown chitin metabolism in Orciraptor, potentially also involved in the feeding process. Our findings provide first molecular insights into an important microbial feeding behaviour, and new directions for cell biology research on non-model eukaryotes.

Factors Affecting Efficiency of Biosorption of Fe (III) and Zn (II) by Ulva lactuca and Corallina officinalis and Their Activated Carbons

The removal of heavy metals from industrial waste has become crucial in order to maintain water quality levels that are suitable for environmental and species reproductive health. The biosorption of Zn+2 and Fe+3 ions from aqueous solution was investigated using Ulva lactuca green algal biomass and Corallina officinalis red algal biomass, as well as their activated carbons. The effects of biosorbent dosage, pH, contact time, initial metal concentration, and temperature on biosorption were evaluated. The maximum monolayer capacity of Ulva lactuca and Corallina officinalis dry algal powder and algal activated carbon was reached at pH 5 and 3 for Zn+2 and Fe+3, respectively, while the other factors were similar for both algae, which were: contact time 120 min, adsorbent dose 1 g, temperature 40 °C and initial concentrations of metal ion 50 mg·L−1. The batch experimental data can be modelled using the Langmuir and Freundlich isotherm models. Thermodynamic characteristics revealed that the adsorption process occurs naturally and is endothermic and spontaneous. For the adsorption of Zn+2 and Fe+3 ions, the value of G° was found to be negative, confirming the practicality of the spontaneous adsorption process, which could be helpful for remediation in the era of temperature increases.

18S and ITS2 rDNA sequence-structure phylogeny of Prototheca (Chlorophyta, Trebouxiophyceae)

Protothecosis is an infectious disease caused by organisms currently classified within the green algal genus Prototheca. The disease can manifest as cutaneous lesions, olecranon bursitis or disseminated or systemic infections in both immunocompetent and immunosuppressed patients. Concerning diagnostics, taxonomic validity is important. Prototheca, closely related to the Chlorella species complex, is known to be polyphyletic, branching with Auxenochlorella and Helicosporidium. The phylogeny of Prototheca was discussed and revisited several times in the last decade; new species have been described. Phylogenetic analyses were performed using ribosomal DNA (rDNA) and partial mitochondrial cytochrome b (cytb) sequence data. In this work we use Internal Transcribed Spacer 2 (ITS2) as well as 18S rDNA data. However, for the first time, we reconstruct phylogenetic relationships of Prototheca using primary sequence and RNA secondary structure information simultaneously, a concept shown to increase robustness and accuracy of phylogenetic tree estimation. Using encoded sequence-structure data, Neighbor-Joining, Maximum-Parsimony and Maximum-Likelihood methods yielded well-supported trees in agreement with other trees calculated on rDNA; but differ in several aspects from trees using cytb as a phylogenetic marker. ITS2 secondary structures of Prototheca sequences are in agreement with the well-known common core structure of eukaryotes but show unusual differences in their helix lengths. An elongation of the fourth helix of some species seems to have occurred independently in the course of evolution.

Some strains from microalgae collection IBASU-A (Ukraine) as an object of biotechnology

An information on the collection of strains of biotechnological application as an integral part of Microalgal Culture Collection of the M.G. Kholodny Institute of Botany of NAS of Ukraine (IBASU-A) is given. The base of its funds contains some green algal strains belonging to the families of Dunaliellaceae, Chlorellaceae, Scenedesmaceae and Selenastraceae. They have been isolated from different regions of Ukraine in order to find cultures of phototrophic microorganisms – promising for biotechnology, in particular, obtaining biologically active additives for the needs of the food industry, medicine, agriculture, raw materials for the production of biofuels, as well as bioindication, biomonitoring, bioremediation of aquatic objects of the environment, etc. Overall, this special collection includs 90 strains of halophile and freshwater microalgae of 30 species, 15 genera, 7 families, 4 orders, 2 classes. All of them are considered as important objects for industrial cultivation, solution of environmental problems, and the basis for further biotechnological research.

Morphological and phylogenetic relations of members of the genus Coelastrella (Scenedesmaceae, Chlorophyta) from the Ural and Khentii Mountains (Russia, Mongolia)

We describe the morphological features and the phylogenetic relationships of five morphologically similar strains belonging to the genus Coelastrella, which live in different ecological and geographical conditions of terrestrial ecosystems: in the Ural Mountains (Polar, Subpolar, and Northern Urals of Russia) and the Khentii Mountains (Russia and Mongolia). We analysed algal strains stored in the Culture Collection of Algae of the Institute of Biology, Syktyvkar, Russia (SYKOA Ch-045-09, SYKOA Ch-047-11, SYKOA Ch-072-17) and the Culture Collection of Algae at Herbarium of the Siberian Institute of Plant Physiology and Biochemistry, Irkutsk, Russia (IRK-A 2, IRK-A 173). By light microscopy, all samples were assigned to Coelastrella terrestris. However, the phylogenetic analyses based on the nucleotide sequences of 18S rDNA and ITS1-ITS2 showed that only one strain belongs to C. terrestris (IRK-A 173). Other samples were closer to C. oocystiformis (SYKOA Ch-045-09; IRK-A 2) and C. aeroterrestrica (SYKOA Ch-047-11). The strain SYKOA Ch-072-17 is probably a new species for the genus. These results confirmed the high phenotypic variability and the hidden diversity among the members of this green algal group.

Assessment of Water Quality and Phytoplankton Structure of Eight Alexandria Beaches, Southeastern Mediterranean Sea, Egypt

This study aims to investigate the abundance, community, and structure of phytoplankton, physicochemical parameters, and some eutrophication state indices, to estimate the water quality of eight selected beaches along the Alexandria Coast, in the southeast of the Mediterranean Sea. The samples were collected monthly from 2019 to 2020. Nutrient values ranged from 1.54 to 33.21 µM for nitrate, 0.01 to 1.98 µM for nitrite, 0.12 to 9.45 µM for ammonia, 0.01 to 1.54 µM for phosphate, and 0.67 to 29.53 µM for silicate. Phytoplankton biomass was characterized by chlorophyll-a concentration, which fluctuated between 0.12 and 12.31 µg L−1. The annual phytoplankton average was 63.85 ± 17.83 × 103 cells L−1. Phytoplankton was highly diversified (228 taxa), and the most diversified group was diatoms (136 taxa), followed by a remarkably low number of Dinophyta (36 taxa). Diatoms reached maximum abundance in December. Meanwhile, a dense bloom of microalga Chlorella marina occurred in June on some beaches. High temperature, high dissolved inorganic nitrogen, and less-saline waters have supported green algal proliferation. The Shannon–Wiener diversity index (H’) showed that there was a qualitative seasonal difference in the composition of the phytoplankton community. Waters of beaches 1–3 were classified as between clean and moderately polluted; and beaches 4–8 varied between moderately and heavily polluted. The study revealed that human activities might have triggered the algal bloom and may be responsible for alterations in the Alexandria coast ecosystem.

A new lineage of non-photosynthetic green algae with extreme organellar genomes

Background: The plastid genomes of the green algal order Chlamydomonadales tend to expand their non-coding regions, but this phenomenon is poorly understood. Here we shed new light on organellar genome evolution in Chlamydomonadales by studying a previously unknown non-photosynthetic lineage. We established cultures of two new Polytoma-like flagellates, defined their basic characteristics and phylogenetic position, and obtained complete organellar genome sequences and a transcriptome assembly for one of them. Results: We discovered a novel deeply diverged chlamydomonadalean lineage that has no close photosynthetic relatives and represents an independent case of photosynthesis loss. To accommodate these organisms, we establish a new genus, Leontynka, with two species L. pallida and L. elongata distinguished by both morphological and molecular characteristics. Notable features of the colourless plastid of L. pallida deduced from the plastid genome (plastome) sequence and transcriptome assembly include the retention of ATP synthase, thylakoid-associated proteins, carotenoid biosynthesis pathway, and plastoquinone-based electron transport chain, the latter two modules having an obvious functional link to the eyespot present in Leontynka. Most strikingly, the L. pallida plastome with its ~362 kbp is by far the largest among non-photosynthetic eukaryotes investigated to date. Instead of a high gene content, its size reflects extreme proliferation of sequence repeats. These are present also in coding sequences, with one repeat type found in exons of 11 out of 34 protein-coding genes and up to 36 copies per gene, affecting thus the encoded proteins. The mitochondrial genome of L. pallida is likewise exceptionally large, with its >104 kbp surpassed only by the mitogenome of Haematococcus lacustris among all members of Chlamydomonadales studied so far. It is also bloated with repeats, yet completely different from those in the L. pallida plastome, which contrasts with the situation in H. lacustris where both organellar genomes have accumulated related repeats. Furthermore, the L. pallida mitogenome exhibits an extremely high GC content in both coding and non-coding regions and, strikingly, a high number of predicted G-quadruplexes. Conclusions: With the unprecedented combination of plastid and mitochondrial genome characteristics, Leontynka pushes the frontiers of organellar genome diversity and becomes an interesting model for studying organellar genome evolution.