Adverse effects of UV-B radiation on plants growing at schirmacher oasis, East Antarctica

Abstract

This study aimed to assess the impacts of ultraviolet-B (UV-B) radiation over a 28-day period on the levels of pigments of Umbilicaria aprina and Bryum argenteum growing in field. The depletion of stratospheric ozone is most prominent over Antarctica, which receives more UV-B radiation than most other parts of the planet. Although UV-B radiation adversely affects all flora, Antarctic plants are better equipped to survive the damaging effects of UV-B owing to defenses provided by UV-B absorbing compounds and other screening pigments. The UV-B radiations and daily average ozone values were measured by sun photometer and the photosynthetic pigments were analyzed by the standard spectrophotometric methods of exposed and unexposed selected plants. The daily average atmospheric ozone values were recorded from 5 January to 2 February 2008. The maximum daily average for ozone (310.7 Dobson Units (DU)) was recorded on 10 January 2008. On that day, average UV-B spectral irradiances were 0.016, 0.071, and 0.186 W m-2 at wavelengths of 305, 312, and 320 nm, respectively. The minimum daily average ozone value (278.6 DU) was recorded on 31 January 2008. On that day, average UV-B spectral irradiances were 0.018, 0.085, and 0.210 W m-2 at wavelengths of 305, 312, and 320 nm, respectively. Our results concludes that following prolonged UV-B exposure, total chlorophyll levels decreased gradually in both species, whereas levels of UV-B absorbing compounds, phenolics, and carotenoids gradually increased.

Effects of Ultraviolet-B Radiation in Plant Physiology

“…UV-B reduces the content of photosynthetic pigments in the chloroplast, especially chlorophyll a, which is considered the principal pigment in photosynthesis (Qi et al 2003;Gupta et al 2008;Juozaityte et al 2008;Lidon & Ramalho 2011;Singh & Singh 2014;Sztatelman et al 2015;Ayash et al 2017;Fu & Shen 2017;Sebastian et al 2018). This loss in chlorophyll can be attributed to protochlorophyllide photoreduction to chlorophyllide by protochlorophyllide oxidoreductase during the early stages of chlorophyll biosynthesis, as well as chlorophyllase induction, which is responsible for chlorophyll breakdown (Agrawal 1996;Marwood & Greenberg 1996;Pradhan et al 2006;Sakalauskaite et al 2013;Ganapathy et al 2017;Rai & Agrawal 2017).…”

“…It`s worth noting that flavonoids are sensitive to light quality, thus their concentrations are higher in plant cells exposed UV radiation (Olsson et al 1998;Izaguirre et al 2007;Katerova et al 2012;Inostroza-Blancheteau et al 2014;Li et al 2014;Singh & Singh, 2014;Suleman et al 2014;Köhler et al 2017;Bilodeau et al 2019;Liu et al 2020).…”

“…Increased flavonoid content under lower exposure correlates well with higher activity of phenylalanine ammonia-lyase (PAL), a key enzyme of flavonoid biosynthesis (Kolb et al 2001;Kumari et al 2009;Singh & Singh, 2014;Suleman et al 2014;Azarafshan et al 2020).…”

“…Several studies implied the rise in anthocyanins under UV-B stress (Tsormpatsidis et al 2008;Inostroza-Blancheteau et al 2014;Singh & Singh 2014;Reyes-Díaz et al 2016;Sebastian et al 2018;Del Valle et al 2020).…”

Different regulations of cell-type transcription by UV-B in multicellular green alga Volvox carteri

“…Such effects are studied to induce defense mechanisms or photomorphogenic responses in a range of higher plants such as Arabidopsis thaliana, Brassica rapa, Glycine max, Vitis vinifera, as well as in lower plants like Umbilicaria aprina, Bryum argenteum, Kappaphycus alvarezii, C. reinhardtii, Micromonas commode and Chlorella sp. [3][4][5][6][7][8][9][10][11] According to these studies, UV-B radiation generally affects signaling, the regulation of gene expression, and biological pathways in plants. However, other model plant species should be investigated to better understand these processes.…”