Increased Cuticle Waxes by Overexpression of WSD1 Improves Osmotic Stress Tolerance in Arabidopsis thaliana and Camelina sativa

To ensure global food security under the changing climate, there is a strong need for developing ‘climate resilient crops’ that can thrive and produce better yields under extreme environmental conditions such as drought, salinity, and high temperature. To enhance plant productivity under the adverse conditions, we constitutively overexpressed a bifunctional wax synthase/acyl-CoA:diacylglycerol acyltransferase (WSD1) gene, which plays a critical role in wax ester synthesis in Arabidopsis stem and leaf tissues. The qRT-PCR analysis showed a strong upregulation of WSD1 transcripts by mannitol, NaCl, and abscisic acid (ABA) treatments, particularly in Arabidopsis thaliana shoots. Gas chromatography and electron microscopy analyses of Arabidopsis seedlings overexpressing WSD1 showed higher deposition of epicuticular wax crystals and increased leaf and stem wax loading in WSD1 transgenics compared to wildtype (WT) plants. WSD1 transgenics exhibited enhanced tolerance to ABA, mannitol, drought and salinity, which suggested new physiological roles for WSD1 in stress response aside from its wax synthase activity. Transgenic plants were able to recover from drought and salinity better than the WT plants. Furthermore, transgenics showed reduced cuticular transpirational rates and cuticle permeability, as well as less chlorophyll leaching than the WT. The knowledge from Arabidopsis was translated to the oilseed crop Camelina sativa (L.) Crantz. Similar to Arabidopsis, transgenic Camelina lines overexpressing WSD1 also showed enhanced tolerance to drought stress. Our results clearly show that the manipulation of cuticular waxes will be advantageous for enhancing plant productivity under a changing climate

Prolonged Drying Trend Coincident with the Demise of Norse Settlement in Southern Greenland

Declining temperature has been thought to explain the abandonment of Norse settlements, southern Greenland, in the early 15th century, although limited paleoclimate evidence is available from the inner settlement region itself. Here, we reconstruct the temperature and hydroclimate history from lake sediments at a site adjacent to a former Norse farm. We find no substantial temperature changes during the settlement period but rather that the region experienced a persistent drying trend, which peaked in the 16th century. Drier climate would have notably reduced grass production, which was essential for livestock overwintering, and this drying trend is concurrent with a Norse diet shift. We conclude that increasingly dry conditions played a more important role in undermining the viability of the Eastern Settlement than minor temperature changes

brGDGT data from Lake 578, southern Greenland

This dataset includes branched glycerol dialkyl glycerol tetraether (brGDGT) fractional abundances from sediment core, surface sediments, settling particulate matter, and soils of Lake 578 (61.08° N, 45.61° W), southern Greenland. BrGDGTs are lipids thought to be biosynthesized by anaerobic bacteria. These compounds are abundant in lake sediments and potentially can be used as proxies for evaluating past environmental conditions. To improve the application of the brGDGT paleothermometer in high latitudes, we examine brGDGTs distribution from Lake 578, located in southern Greenland. In July 2016, a 70 cm percussion core was collected from Lake 578, and the sediment trap system was deployed. Sediment traps were assembled using a 25.5 cm diameter funnel with a 100 mL centrifuge tube attached at the bottom and allowed to accumulate material for 1 year. Three sediment traps were placed at 5 m, 10 m, and 14 m depths. Each summer (2017, 2018, and 2019) the sediment traps were recovered, the centrifuge tubes exchanged with new ones, and the traps re-deployed at the same location. 5 surface sediment samples were collected with an Ekman grab sampler in July 2018. 13 catchment soil samples were collected from the Lake 578 watershed area. Sediment trap samples, surface sediment samples, and soil samples were frozen until analysis. The sediment core was stored at 4 °C until analysis. All brGDGT samples were analyzed on an Agilent 1260 UHPLC coupled to an Agilent 6120 MSD with the newer methods of Hopmans et al. (2016) to separate the compounds