Multivariate analysis of intraspecific responses to UV‐B radiation in white clover (Trifolium repensL.)

Abstract

White clover (Trifolium repens L.) is experiencing increased levels of ultraviolet-B (UV-B) radiation in temperate pastures due to the depletion of the stratospheric ozone layer. Based on 17 morphological, morphogenetic and physiological attributes, this study analysed the consequences of enhanced UV-B on 26 white clover populations using principal components analysis (PCA). After 18 d of exposure to 13·3 kJ m -2 d -1 UV-B in controlled environments, UV-B significantly decreased above-ground and below-ground plant growth attributes, epidermal cell surface area and maximum quantum efficiency of photosystem II photochemistry (F v /F m ). Aspects of cell division and cell expansion both were negatively affected by UV-B. Stomatal density, specific leaf mass, root-to-shoot ratio and levels of UV-B-absorbing compounds increased in response to UV-B. In the multivariate analysis, the main dimension of UV-B sensitivity was characterized by changes in plant growth attributes. Alterations in partitioning within and between plant organs constituted a secondary tier of UV-B responsiveness. Plant characteristics related to UV-B tolerance included lower growth rate, smaller epidermal cell surface area and higher UV-B-induced levels of UV-Babsorbing compounds. The results suggest overall UV-B tolerance for slower-growing populations from less productive habitats with higher natural UV-B irradiance.

Influence of ambient and enhanced ultraviolet-B radiation on the plant growth and physiological properties in two contrasting populations of Hippophae rhamnoides

“…In contrast, compared with NA, +UVB caused significant inhibition of photosynthesis (A), total leaf area and biomass accumulation in the low-altitude population (Tables 1, 2), paralleling the significant reduction in antioxidant content (Asa) (Tables 2, 3), which further led to lower tolerance to +UVB. Previous studies also documented that plant populations from high UV-B habitats were more tolerant to enhanced UV-B (Hofmann et al 2001;Ren et al 2006), and our study showed that the intraspecific differences of plant responses to UV-B were closely related with plant characteristics of leaf morphology, antioxidant capacity and physiological modifications.…”

Intraspecific responses of Fagopyrum esculentum to enhanced ultraviolet B radiation

“…1b, 2). Previous studies on Arabidopsis thaliana, white clover and tartary buckwheat indicated that UV-B induced changes in plant traits were negatively correlated with their constitutive values under control conditions (Cooley et al 2001;Hofmann et al 2001, Yao et al 2007. We also observed that the low constitutive values in terms of growth and yield-related parameters in the high elevation cultivar remained less affected than lowland cultivars.…”

“…However, impaired SOD activity and reduced Asa concentration under high level of UV-B radiation suggested that the plants are unable to cope with high stress intensity and that oxidative damage could be, at least partly, responsible for plant growth inhibition and ultimate yield decrease (Jansen et al 1998). Plant populations originating from high UV-B habitats are supposed to be more tolerant to UV-B radiation than those from low UV-B origin (Teramura and Sullivan 1991;Yang et al 2005) since the high elevation plants should have selected adaptative strategies (Hofmann et al 2001). Our results showed that the high elevation cultivar exhibits a high adaptability to its original ambient UV-B radiation (+5.0 kJ m -2 UV-B) while the lowland cultivars would suffer from marked reductions in growth, final yield and dry matter accumulation if they are cultivated in Qinghai-Tibet plateau region.…”

On the Different Sensitivity of White Clover Clones to Ozone: Physiological and Biochemical Parameters in a Multivariate Approach

“…The multivariate assessment was further used to explore whether constitutive features could be linked to the overall O 3 responsiveness of the white clover clones. Similar multivariate analytical approaches have been used in other investigations on stress sensitivity/tolerance (Somersalo et al, 1998;Hofmann et al, 2001). However, there is a general shortage of multivariate investigations in the examination of O 3 responses in plants.…”