title: UV radiation reduces epidermal cell expansion in leaves of Arabidopsis thaliana.
abstract: Plants have evolved a broad spectrum of mechanisms to ensure survival under changing and suboptimal environmental conditions. Alterations of plant architecture are commonly observed following exposure to abiotic stressors. The mechanisms behind these environmentally controlled morphogenic traits are, however, poorly understood. In this report, the effects of a low dose of chronic ultraviolet (UV) radiation on leaf development are detailed. Arabidopsis rosette leaves exposed for 7, 12, or 19 d to supplemental UV radiation expanded less compared with non-UV controls. The UV-mediated decrease in leaf expansion is associated with a decrease in adaxial pavement cell expansion. Elevated UV does not affect the number and shape of adaxial pavement cells, nor the stomatal index. Cell expansion in young Arabidopsis leaves is asynchronous along a top-to-base gradient whereas, later in development, cells localized at both the proximal and distal half expand synchronously. The prominent, UV-mediated inhibition of cell expansion in young leaves comprises effects on the early asynchronous growing stage. Subsequent cell expansion during the synchronous phase cannot nullify the UV impact established during the asynchronous phase. The developmental stage of the leaf at the onset of UV treatment determines whether UV alters cell expansion during the synchronous and/or asynchronous stage. The effect of UV radiation on adaxial epidermal cell size appears permanent, whereas leaf shape is transiently altered with a reduced length/width ratio in young leaves. The data show that UV-altered morphogenesis is a temporal- and spatial-dependent process, implying that common single time point or single leaf zone analyses are inadequate.
authors: Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
authors: Kathleen
authors: K
authors: Hectors
authors: Eveline
authors: E
authors: Jacques
authors: Els
authors: E
authors: Prinsen
authors: Yves
authors: Y
authors: Guisez
authors: Jean-Pierre
authors: JP
authors: Verbelen
authors: Marcel A K
authors: MA
authors: Jansen
authors: Kris
authors: K
authors: Vissenberg
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000528:radiation effects*; D002452:Cell Count; D016764:Cell Polarity / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D048430:Cell Shape / Q000528:radiation effects; D019441:Plant Epidermis / Q000166:cytology* / Q000528:radiation effects*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000166:cytology* / Q000254:growth & development / Q000528:radiation effects*; D054046:Plant Stomata / Q000166:cytology / Q000528:radiation effects; D013997:Time Factors; D014466:Ultraviolet Rays