UV‐B Radiation Impacts Shoot Tissue Pigment Composition in Allium fistulosum L. Cultigens

Abstract

Plants from the Allium genus are valued worldwide for culinary flavor and medicinal attributes. In this study, 16 cultigens of bunching onion (Allium fistulosum L.) were grown in a glasshouse under filtered UV radiation (control) or supplemental UV-B radiation [7.0 μmol·m−2 ·s−2 (2.68 W·m−2)] to determine impacts on growth, physiological parameters, and nutritional quality. Supplemental UV-B radiation influenced shoot tissue carotenoid concentrations in some, but not all, of the bunching onions. Xanthophyll carotenoid pigments lutein and β-carotene and chlorophylls a and b in shoot tissues differed between UV-B radiation treatments and among cultigens. Cultigen “Pesoenyj” responded to supplemental UV-B radiation with increases in the ratio of zeaxanthin + antheraxanthin to zeaxanthin + antheraxanthin + violaxanthin, which may indicate a flux in the xanthophyll carotenoids towards deepoxydation, commonly found under high irradiance stress. Increases in carotenoid concentrations would be expected to increase crop nutritional values.

Narrowband Blue and Red LED Supplements Impact Key Flavor Volatiles in Hydroponically Grown Basil Across Growing Seasons

“…Cryptochromes act as signaling mechanisms that regulate circadian rhythms and prompt many physiological and morphological changes; phototropins control chloroplast movements to maximize absorption of specific wavelengths (Christie, 2007;Chaves et al, 2011;Kopsell et al, 2014). Changes in specific B wavelengths that target phototropins or cryptochromes have the ability to impact primary and secondary metabolism, volatile production, carotenoid and chlorophyll pigment bioaccumulation, circadian rhythms, stomatal opening/closing, intermodal length, leaf area and thickness, and intracellular structure configurations/positioning (Lichtenthaler, 1987;Frank and Cogdell, 1996;Briggs and Huala, 1999;Briggs and Christie, 2002;Christie, 2007;Abney et al, 2013;Kopsell and Sams, 2013;Metallo et al, 2018;Bantis et al, 2020;Samuoliene et al, 2020). Intensity changes to specific B wavelengths that target phytochromes have also been shown to impact germination rates, vegetative and reproductive growth/development, leaf size/thickness, phenolic and antioxidant pathways, etc.…”

“…(Li and Kubota, 2009;Olle and Viršile, 2013;Landi et al, 2020). Exposure to UV light and specific B wavelengths have been shown to result in higher concentrations of favorable flavor volatiles in many high-value crops such as mint (Mentha piperita) (Lucchesi et al, 2004;Hikosaka et al, 2010;Treadwell et al, 2011), thyme (Thymus vulgaris) (Lee et al, 2005), strawberries (Fragaria × ananassa) (Colquhoun et al, 2013), chives (Allium fistulosum) (Abney et al, 2013), lettuce (Lactuca sativa L.) (Baumbauer et al, 2019;Chen et al, 2019;Kong et al, 2019;Yan et al, 2019;Zhang et al, 2019;Samuoliene et al, 2020), and basil (Ocimum basilicum) (Loughrin and Kasperbauer, 2003;Kopsell et al, 2005;Lee et al, 2005;Deschamps and Simon, 2006;Chalchat and Ozcan, 2008;Hussain et al, 2008;Klimánková et al, 2008;Bantis et al, 2016;Carvalho et al, 2016).…”

“…Wavelengths greater than 1,000 nm contain IR radiation, which is primarily converted into heat energy. These wavebands are not particularly useful to plants for primary or secondary metabolism and are not used for photosynthesis (McCree, 1973;Barta et al, 1992;Goins et al, 1997;Briggs and Huala, 1999;Lucchesi et al, 2004;Morrow, 2008;Abney et al, 2013;Tuan et al, 2013;Kopsell et al, 2014).…”

Carotenoids from Persimmon (Diospyros kaki Thunb.) Byproducts Exert Photoprotective, Antioxidative and Microbial Anti-Adhesive Effects on HaCaT

“…against UV-B radiation relates to photoprotection by its carotenoid pigments [17]. Likewise, carotenoids and other health-promoting compounds, such as chlorophylls and flavonoids, can be elicited by increasing the levels of supplemental UV-B radiation in plants, bacteria, and algae [18][19][20][21]. Overall, natural carotenoids have evolved to play key roles in absorbing different wavelengths, according to their structure [12].…”