Flavone Synthase II (CYP93B) of Antarctic Plant Colobanthus quitensis (Kunth) Bartl.

The role of flavonoids in plant-environmental stress has many biotechnological applications, in this way Antarctic plants have an important potential for molecular farming. However, the concentration and exploitation of resource are highly restricted, for this reason the use of enzymatic machinery of the Antarctic plants have importance for in vitro flavonoid production for different biotechnological applications. Despite their potential applications, key enzymes for flavonoid biosynthesis are poorly studied in non-model plants. In this work, we studied the flavonoid key enzyme, flavone synthase II (FNS II) in C. quitensis. The results show a cooperative kinetic model for NADPH and naringenin. The temperature and pH stability assays show optimal temperature between 20-30 °C, with an operative range from 2 to 37 °C, pH stability shows an optimum of 7.0 to 8.0, with operative range from 3.0 to 8.0, demonstrating a big thermal and pH-stability, an interesting characteristic to in vitro production of flavones.

Root fungal endophytes improve the growth of antarctic plants through an enhanced nitrogen acquisition

Mutualistic symbiosis with fungal endophytes has been suggested as a possible mechanism for extreme environment colonization by Antarctic vascular plants. Fungal endophytes improve plant stress tolerance and performance by increasing plant hormone production and the uptake of water and nutrients. However, there are still gaps regarding the mechanisms by which these process ocurr. This work explores the role of root fungal endophytes in the production of exolytic enzymes involved in endophyte-mediated mineralization and nutrient uptake, as well as their impact on the performance of Antarctic plants. Hence, we evaluated the ability of fungal endophytes isolated from the two native Antarctic vascular plants, Colobanthus quitensis and Deschampsia antarctica, to enzymatically degrade different nutrient sources, mediate nitrogen mineralization and enhance growth of the host plant. Single-spore derived isolates were identified using molecular and morphological approaches. Penicillium chrysosgenum and Penicillium brevicompactum were identified as the dominant root endophytes in C. quitensis and D. antarctica, respectively. Root endophytes exhibited hydrolytic and oxidative enzymatic activities involved in carbohydrate or protein breakdown and phosphorus solubilization. In addition, the rates and porcentages of nitrogen mineralization, as well as the final total biomass were significantly higher in C. quitensis and D. antarctica individuals with root endophytes relative to those without endophytes. Our findings suggest that root endophytes exert a pivotal ecological role based not only on their capability to breakdown different nutrient sources but also accelerating nitrogen mineralization, improving nutrient acquisition and promoting plant growth in limited nutrient soils in Antarctic terrestrial ecosystems

Root fungal endophytes improve the growth of antarctic plants through an enhanced nitrogen acquisition

Mutualistic symbiosis with fungal endophytes has been suggested as a possible mechanism for extreme environment colonization by Antarctic vascular plants. Fungal endophytes improve plant stress tolerance and performance by increasing plant hormone production and the uptake of water and nutrients. However, there are still gaps regarding the mechanisms by which these process ocurr. This work explores the role of root fungal endophytes in the production of exolytic enzymes involved in endophyte-mediated mineralization and nutrient uptake, as well as their impact on the performance of Antarctic plants. Hence, we evaluated the ability of fungal endophytes isolated from the two native Antarctic vascular plants, Colobanthus quitensis and Deschampsia antarctica, to enzymatically degrade different nutrient sources, mediate nitrogen mineralization and enhance growth of the host plant. Single-spore derived isolates were identified using molecular and morphological approaches. Penicillium chrysosgenum and Penicillium brevicompactum were identified as the dominant root endophytes in C. quitensis and D. antarctica, respectively. Root endophytes exhibited hydrolytic and oxidative enzymatic activities involved in carbohydrate or protein breakdown and phosphorus solubilization. In addition, the rates and porcentages of nitrogen mineralization, as well as the final total biomass were significantly higher in C. quitensis and D. antarctica individuals with root endophytes relative to those without endophytes. Our findings suggest that root endophytes exert a pivotal ecological role based not only on their capability to breakdown different nutrient sources but also accelerating nitrogen mineralization, improving nutrient acquisition and promoting plant growth in limited nutrient soils in Antarctic terrestrial ecosystems

Colonisation of stranded whale bones by lichens and mosses at Hennequin Point, King George Island, Antarctica

ABSTRACTThis paper presents the details of lichens and mosses found on whale vertebrae substratum in the Admiralty Bay area, King George Island, Antarctica. Samples were taken in the coastal area at Hennequin Point, a relict of the Antarctic whaling era. The samples were collected from the upper surface of the whale bones found in the study area during the austral summer 2010–2011. A total of 15 lichen and two moss species were found. All species sampled are known in the Admiralty Bay area, both as pioneers and in more advanced succession stages in ice-free areas. These results suggest that the colonisation of whale bones is not new for Antarctic plants, but it is an additional substrate on which these plants can develop. A map showing the distribution of colonised bones and details of the usual substrata for the lichens and mosses found in this study are provided.