title: Response of purely symbiotic and NO3-fed nodulated plants of Lupinus luteus and Vicia atropurpurea to ultraviolet-B radiation.
abstract: The effects of elevated UV-B radiation on growth, symbiotic function and concentration of metabolites were assessed in purely symbiotic and NO3-fed nodulated plants of Lupinus luteus and Vicia atropurpurea grown outdoors either on tables under supplemental UV-B radiation or in chambers covered with different types of plexi-glass to attenuate solar ultraviolet radiation. Moderately and highly elevated UV-B exposures simulating 15% and 25% ozone depletion as well as sub- ambient UV-B did not alter organ growth, plant total dry matter and N content per plant in both L. luteus and V. atropurpurea. In contrast, elevated UV-B increased (P <0.05) flavonoid and anthocyanin concentrations in roots and leaves of L. luteus, but not of V. atropurpurea. Feeding nodulated plants of L. luteus under elevated UV-B radiation with 2 mM NO3 increased (P <0.05) nodule, leaf and total dry matter, and whole plant N content. With V. atropurpurea, NO3 reduced (P <0.05) nodule activity, root %N and concentrations of flavonoids, anthocyanins in roots and leaves and soluble sugars in roots, in contrast to an observed increase (P <0.05) in nodule dry matter per plant. Similarly, supplying 2 mM NO3 to L. luteus plants exposed to sub-ambient UV-B radiation significantly reduced individual organ growth, plant total biomass, nodule dry matter, nodule %N, and whole plant N content, as well as root concentrations of flavonoids, anthocyanins, soluble sugars, and starch of L. luteus, but not V. atropurpurea plants. These results show no adverse effect of elevated UV-B radiation on growth and symbiotic function of L. luteus and V. atropurpurea plants. However, NO3 supply promoted growth in L. luteus plants exposed to the highly elevated UV-B radiation.
authors.affiliation: Botany Department, University of Cape Town, Private Bag Rhondebosch 7701, South Africa.
authors.forename: Samson B M
authors.initials: SB
authors.lastname: Chimphango
authors.forename: Charles F
authors.initials: CF
authors.lastname: Musil
authors.forename: Felix D
authors.initials: FD
authors.lastname: Dakora
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000528:radiation effects; D000872:Anthocyanins / Q000378:metabolism; D018533:Biomass; D050260:Carbohydrate Metabolism; D005419:Flavonoids / Q000378:metabolism; D031297:Lupinus / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D009566:Nitrates / Q000494:pharmacology*; D013213:Starch / Q000378:metabolism; D013559:Symbiosis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D014466:Ultraviolet Rays; D031306:Vicia / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D000872:Anthocyanins; D005419:Flavonoids; D009566:Nitrates; D013213:Starch