title: Morphological and physiological responses of two varieties of a highland species (Chenopodium quinoa Willd.) growing under near-ambient and strongly reduced solar UV-B in a lowland location.
abstract: Morphological and physiological responses of seedlings to different solar UV-B irradiances were evaluated in two varieties of quinoa (Chenopodium quinoa Willd.), a crop species from Andean region of South America. Cristalina and Chucapaca varieties were grown at 1965m a.s.l in a glasshouse under natural light conditions for 18 days, and then transferred to outdoors under near-ambient (+UV-B) and strongly reduced (-UV-B) solar UV-B radiation. Exposition to -UV-B increased cotyledon area and seedling height in Cristalina variety whereas leaf number decreased compared to +UV-B. By contrast Chucapaca variety was not affected by UV-B treatments. Seedling fresh weight (FW), root length and leaf thickness did not show significant differences between +UV-B and -UV-B treatments. Mesophyll tissue was slightly affected by solar UV-B reduction. Chlorophyll content was differentially affected by UV-B treatments. Under +UV-B the highest value was observed in Cristalina variety, while in Chucapaca it was observed under -UV-B treatment. Chlorophyll content was slightly higher in leaves than in cotyledons, but there was no difference in the distribution pattern. Chlorophyll a/b ratio and carotenoid content did not show significant differences between UV-B treatments. Leaf UVB-absorbing compounds showed significant differences between UV-B treatments in Chucapaca only, while there were no significant differences in Cristalina variety. UVB-absorbing compounds of cotyledons did not show significant differences between +UV-B and -UV-B treatments. Sucrose, glucose and fructose showed different distribution patterns in cotyledons and leaves of the two varieties under near-ambient and strongly reduced UV-B. Results demonstrated that varieties of quinoa exhibit different morphological and physiological responses to changes in solar UV-B irradiance, but these responses cannot be used to predict the sensitivity to solar UV-B during a short-term exposition. Also, this study can be useful to learn about the plasticity of metabolic pathways involved in plant's tolerance to solar UV-B radiation.
authors.affiliation: Fundación Miguel Lillo, Area de Ecología Vegetal, Tucumán, Argentina.
authors.forename: Juan A
authors.initials: JA
authors.lastname: González
authors.forename: Mariana
authors.initials: M
authors.lastname: Rosa
authors.forename: María F
authors.initials: MF
authors.lastname: Parrado
authors.forename: Mirna
authors.initials: M
authors.lastname: Hilal
authors.forename: Fernando E
authors.initials: FE
authors.lastname: Prado
mesh_terms: D027465:Chenopodium quinoa / Q000145:classification / Q000254:growth & development* / Q000528:radiation effects*; D002734:Chlorophyll / Q000528:radiation effects; D018548:Cotyledon / Q000737:chemistry / Q000528:radiation effects; D018515:Plant Leaves / Q000737:chemistry / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D002734:Chlorophyll