Characterization of a recently evolved flavonol-phenylacyltransferase gene provides signatures of natural light selection in Brassicaceae

Incidence of natural light stress renders it important to enhance our understanding of the mechanisms by which plants protect themselves from harmful effects of UV-B irradiation, as this is critical for fitness of land plant species. Here we describe natural variation of a class of phenylacylated-flavonols (saiginols), which accumulate to high levels in floral tissues of Arabidopsis. They were identified in a subset of accessions, especially those deriving from latitudes between 16° and 43° North. Investigation of introgression line populations using metabolic and transcript profiling, combined with genomic sequence analysis, allowed the identification of flavonol-phenylacyltransferase 2 (FPT2) that is responsible for the production of saiginols and conferring greater UV light tolerance in planta. Furthermore, analysis of polymorphism within the FPT duplicated region provides an evolutionary framework of the natural history of this locus in the Brassicaceae

Ecology and biogeochemistry of cyanobacteria in soils, permafrost, aquatic and cryptic polar habitats

Polar Regions (continental Antarctica and the Arctic) are characterized by a range of extreme environmental conditions, which impose severe pressures on biological life. Polar cold-active cyanobacteria are uniquely adapted to withstand the environmental conditions of the high latitudes. These adaptations include high ultra-violet radiation and desiccation tolerance, and mechanisms to protect cells from freeze–thaw damage. As the most widely distributed photoautotrophs in these regions, cyanobacteria are likely the dominant contributors of critically essential ecosystem services, particularly carbon and nitrogen turnover in terrestrial polar habitats. These habitats include soils, permafrost, cryptic niches (including biological soil crusts, hypoliths and endoliths), ice and snow, and a range of aquatic habitats. Here we review current literature on the ecology, and the functional role played by cyanobacteria in various Arctic and Antarctic environments. We focus on the ecological importance of cyanobacterial communities in Polar Regions and assess what is known regarding the toxins they produce. We also review the responses and adaptations of cyanobacteria to extreme environments.University of Pretoria Research Development Program (TPM),Genomics Research Institute,The National Research Foundation (NRF) of SouthAfrica’s National Antarctic Program (SANAP program) (TPM, AV, EG.MW VG, DAC) and Ministeriode Economıa y Competitividad (Spain) : Grantref CTM 2011-28736 (DV,AQ).http://link.springer.com/journal/105312016-03-10hb201

Bacterial community structure in a sympagic habitat expanding with global warming: brackish ice brine at 85–90 °N

© 2018, International Society for Microbial Ecology.Larger volumes of sea ice have been thawing in the Central Arctic Ocean (CAO) during the last decades than during the past 800,000 years. Brackish brine (fed by meltwater inside the ice) is an expanding sympagic habitat in summer all over the CAO. We report for the first time the structure of bacterial communities in this brine. They are composed of psychrophilic extremophiles, many of them related to phylotypes known from Arctic and Antarctic regions. Community structure displayed strong habitat segregation between brackish ice brine (IB; salinity 2.4–9.6) and immediate sub-ice seawater (SW; salinity 33.3–34.9), expressed at all taxonomic levels (class to genus), by dominant phylotypes as well as by the rare biosphere, and with specialists dominating IB and generalists SW. The dominant phylotypes in IB were related to Candidatus Aquiluna and Flavobacterium, those in SW to Balneatrix and ZD0405, and those shared between the habitats