title: UV-B impairs growth and gas exchange in grapevines grown in high altitude.
abstract: We previously demonstrated that solar ultraviolet-B (UV-B) radiation levels in high altitude vineyards improve berry quality in Vitis vinifera cv. Malbec, but also reduce berry size and yield, possibly as a consequence of increased oxidative damage and growth reductions (lower photosynthesis). The defense mechanisms toward UV-B signal and/or evoked damage promote production of antioxidant secondary metabolites instead of primary metabolites. Purportedly, the UV-B effects will depend on tissues developmental stage and interplay with other environmental conditions, especially stressful situations. In this work, grapevines were exposed to high solar UV-B (+UV-B) and reduced (by filtering) UV-B (-UV-B) treatments during three consecutive seasons, and the effects of UV-B, developmental stages and seasons on the physiology were studied, i.e. growth, tissues morphology, photosynthesis, photoprotective pigments, proline content and antioxidant capacity of leaves. The +UV-B reduced photosynthesis and stomatal conductance, mainly through limitation in gas exchange, reducing plant's leaf area, net carbon fixation and growth. The +UV-B augmented leaf thickness, and also the amounts of photoprotective pigments and proline, thereby increasing the antioxidant capacity of leaves. The defense mechanisms triggered by + UV-B reduced lipid peroxidation, but they were insufficient to protect the photosynthetic pigments per leaf dry weight basis. The +UV-B effects depend on tissues developmental stage and interplay with other environmental conditions such as total radiation and air temperatures.
authors.affiliation: Laboratorio de Bioquímica Vegetal, Instituto de Biología Agrícola de Mendoza (IBAM), Facultad de Ciencias Agrarias, CONICET-Universidad Nacional de Cuyo, Mendoza, Argentina. fberli@fca.uncu.edu.ar
authors.forename: Federico J
authors.initials: FJ
authors.lastname: Berli
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Alonso
authors.forename: Ricardo
authors.initials: R
authors.lastname: Bressan-Smith
authors.forename: Rubén
authors.initials: R
authors.lastname: Bottini
mesh_terms: D000531:Altitude; D000975:Antioxidants / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D015227:Lipid Peroxidation; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000502:physiology; D054046:Plant Stomata; D011392:Proline / Q000378:metabolism; D013472:Sunlight; D014466:Ultraviolet Rays; D027843:Vitis / Q000254:growth & development* / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D000975:Antioxidants; D002734:Chlorophyll; D002338:Carotenoids; D011392:Proline