Antarctica has one of the most extreme environments on Earth, with low temperatures and low nutrient levels. Antarctica’s organisms live primarily in the coastal, ice-free areas which cover approximately 0.18% of the continent’s surface. Members of Cyanobacteria and eukaryotic algae are important primary producers in Antarctica since they can synthesize organic compounds from carbon dioxide and water using solar energy. However, community structures of photosynthetic algae in Antarctica have not yet been fully explored at molecular level. In this study, we collected diverse algal samples in lacustrine and hydro-terrestrial environments of Langhovde and Skarvsnes, which are two ice-free regions in East Antarctica. We performed deep amplicon sequencing of both 16S ribosomal ribonucleic acid (rRNA) and 18S rRNA genes, and we explored the distribution of sequence variants (SVs) of these genes at single nucleotide difference resolution. SVs of filamentous Cyanobacteria genera, including Leptolyngbya, Pseudanabaena, Phormidium, Nodosilinea, Geitlerinama, and Tychonema, were identified in most of the samples, whereas Phormidesmis SVs were distributed in fewer samples. We also detected unicellular, multicellular or heterocyst forming Cyanobacteria strains, but in relatively small abundance. For SVs of eukaryotic algae, Chlorophyta, Cryptophyta, and Ochrophyta were widely distributed among the collected samples. In addition, there was a red colored bloom of eukaryotic alga, Geminigera cryophile (Cryptophyta), in the Langhovde coastal area. Eukaryotic SVs of Acutuncus antarcticus and/or Diphascon pingue of Tardigrada were dominant among most of the samples. Our data revealed the detailed structures of the algal communities in Langhovde and Skarvsnes. This will contribute to our understanding of Antarctic ecosystems and support further research into this subject.

Pollinosis, also known as pollen allergy or hay fever, is a global problem caused by pollen produced by various plant species. The wind-pollinated Japanese cedar (Cryptomeria japonica) is the largest contributor to severe pollinosis in Japan, where increasing proportions of people have been affected in recent decades. The MALE STERILITY 4 (MS4) locus of Japanese cedar controls pollen production, and its homozygous mutants (ms4/ms4) show abnormal pollen development after the tetrad stage and produce no mature pollen. In this study, we narrowed down the MS4 locus by fine mapping in Japanese cedar and found TETRAKETIDE α-PYRONE REDUCTASE 1 (TKPR1) gene in this region. Transformation experiments using Arabidopsis thaliana showed that single-nucleotide substitution (“T” to “C” at 244-nt position) of CjTKPR1 determines pollen production. Broad conservation of TKPR1 beyond plant division could lead to the creation of pollen-free plants not only for Japanese cedar but also for broader plant species.

Some monocotyledonous plants, including liliaceous, amaryllidaceous and iridaceous ones, produce flowers with petaloid tepals in whorls 1 and 2 organs. For explaining the molecular mechanism of two-layered petaloid tepal development, the modified ABC model has been proposed, in which B class genes are expressed in whorl 1 organs as well as in whorls 2 and 3 organs. We have previously obtained results strongly support the modified ABC model by chimeric repressor gene-silencing technology (CRES-T)-mediated suppression of B function in the liliaceous plant Tricyrtis sp. In the present study, we introduced a CRES-T construct derived from the B class gene of Tricyrtis sp. (TrihDEFa-SRDX) into Lilium sp. in order to examine the effect of suppressing B function on the floral organ identity. Flowers of transgenic plants did not open fully and had pale pink-colored tepals with decreased numbers of papillae on the adaxial side in whorls 1 and 2 compared with those of non-transgenic plants. No apparent morphological alterations were observed in whorls 3 and 4 organs. Both the amount of total anthocyanins and the expression levels of endogenous flavonoid biosynthesis-related genes (LhMYB12, LhbHLH2, LhCHS, LhF3H, LhF3’H, LhDFR and LhANS) decreased in whorls 1 and 2 organs of transgenic plants compared with non-transgenic plants. In addition, the expression levels of endogenous B class genes (LFDEF, LFGLOA and LFGLOB) decreased in transgenic plants and the level was negatively correlated with the degree of morphological alteration. Thus suppression of B function may reduce the identity of petaloid tepals in whorls 1 and 2 of transgenic Lilium sp.

Mosses are distributed all over the world including Antarctica. Although Antarctic mosses show active growth in a short summer season under harsh environments such as low temperature, drought and high levels of UV radiation, survival mechanisms for such multiple environmental stresses of Antarctic mosses have not yet been clarified. In the present study, transcriptome analyses were performed using one of the common mosses Bryum pseudotriquetrum grown under Antarctic field and artificial cultivation conditions. Totally 88,205 contigs were generated by de novo assembly, among which 1,377 and 435 genes were significantly up- and down-regulated, respectively, under Antarctic field conditions compared with artificial cultivation condition at 15 °C. Among the up-regulated genes, a number of lipid metabolism-related and oil body formation-related genes were identified. Expression levels of these genes were increased by artificial environmental stress treatments such as low temperature, salt and osmic stress treatments. Consistent with these results, B. pseudotriquetrum grown under Antarctic field conditions contained large amounts of fatty acids, especially α-linolenic acid, linolenic acid and arachidonic acid. In addition, proportion of unsaturated fatty acids, which enhance membrane fluidity, to the total fatty acids was also higher in B. pseudotriquetrum grown under Antarctic field conditions. Since lipid accumulation and unsaturation of fatty acids are generally important factors for acquisition of various environmental stress tolerance in plants, these intracellular physiological and metabolic changes may be responsible for survival of B. pseudotriquetrum under Antarctic harsh environments.