Response of photosynthesis to high light and drought for Arabidopsis thaliana grown under a UV-B enhanced light regime

Abstract

Arabidopsis thaliana grown in a light regime that included ultraviolet-B (UV-B) radiation (6 kJ m(-2) d(-1)) had similar light-saturated photosynthetic rates but up to 50% lower stomatal conductance rates, as compared to plants grown without UV-B radiation. Growth responses of Arabidopsis to UV-B radiation included lower leaf area (25%) and biomass (10%) and higher UV-B absorbing compounds (30%) and chlorophyll content (52%). Lower stomatal conductance rates for plants grown with UV-B radiation were, in part, due to lower stomatal density on the adaxial surface. Plants grown with UV-B radiation had more capacity to down regulate photochemical efficiency of photosystem II (PSII) as shown by up to 25% lower phi(PSII) and 30% higher non-photochemical quenching of chlorophyll fluorescence under saturating light. These contributed to a smaller reduction in the maximum photochemical efficiency of PSII (F (v)/F (m)), greater dark-recovery of F (v)/F (m), and higher light-saturated carbon assimilation and stomatal conductance and transpiration rates after a four-hour high light treatment for plants grown with UV-B radiation. Plants grown with UV-B were more tolerant to a 12 day drought treatment than plants grown without UV-B as indicated by two times higher photosynthetic rates and 12% higher relative water content. UV-B-grown plants also had three times higher proline content. Higher tolerance to drought stress for Arabidopsis plants grown under UV-B radiation may be attributed to both increased proline content and decreased stomatal conductance. Growth of Arabidopsis in a UV-B-enhanced light regime increased tolerance to high light exposure and drought stress.

Effects of substrate acidity and UV-B radiation on photosynthesis of radishes

“…In addition, the observation that substrate acidity leads to a decrease in chlorophyll a content in leaves is line with other research studies [32,33]. Surprisingly, depending on the experimental conditions, UV-B radiation has been shown to increase [34], decrease [23] or have no effect on chlorophyll content [35]. Much of UV-B radiation is attenuated in leaves by leaf cuticles via UV-absorbing compounds produced and deposited in leaf epidermal cells or hairs [36] or by antioxidant systems [37].…”

Evaluation of drought and UV radiation impacts on above-ground biomass of mountain grassland by spectral reflectance and thermal imaging techniques

“…Alexieva et al 2001;Poulson et al 2006), other findings show synergistic interactions resulting in higher drought sensitivity under enhanced UV radiation (Petropoulou et al 1995;Björn et al 1997).…”

Characterization of the adaptive response of grapevine (cv. Tempranillo) to UV-B radiation under water deficit conditions

“…Regarding the effect of UV-B radiation on plant water status, most of the studies on the response of plants to UV-B show no remarkable changes in leaf RWC [8,9]. In other cases, UV-B has been reported to improve leaf water status, through production of osmolytes, accumulation of dehydrins or increases in cuticle thickness [1].…”