Tilia platyphyllos leaves we found that sun leaves were better protected against stress than 5 shade leaves by having (i) more efficient regulated non-photochemical quenching (ii) a 6 higher capacity to neutralize singlet oxygen, a reactive oxygen species known to be capable 7 of promoting oxidative damage by excess PAR and (iii) containing more UV absorbing

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Members of the aldo-keto reductase family including aldose reductases are involved in antioxidant defense by metabolizing a wide range of lipid peroxidation-derived cytotoxic compounds. Therefore, we produced transgenic wheat genotypes over-expressing the cDNA of alfalfa aldose reductase gene. These plants consequently exhibit 1.5-4.3 times higher detoxification activity for the aldehyde substrate. Permanent drought stress was generated in the greenhouse by growing wheat plants in soil with 20 % water capacity. The control and stressed plants were monitored by a semi automatic phenotyping platform providing computer-controlled watering, digital and thermal imaging. Calculation of biomass values was based on the correlation (R 2 = 0.7556) between fresh weight and green pixel-based shoot surface area. The green biomass production by plants of the three transgenic lines was 12-26-41 % higher than the non-transgenic plants' grown under water limitation. Thermal imaging of stressed nontransgenic plants indicated an elevation in the leaf temperature. The thermal status of transformants was similar at both normal and suboptimal water regime. In drought, the transgenic plants used more water during the growing season. The described phenotyping platform provided a comprehensive data set demonstrating the improved physiological condition of the drought stressed transgenic wheat plants in the vegetative growth phase. In soil with reduced water capacity two transgenic genotypes showed higher seed weight per plant than the control non-transgenic one. Limitation of greenhouse-based phenotyping in analysis of yield potential is discussed.

a b s t r a c tGreenhouse grown tobacco (Nicotiana tabacum L. cv. Petit Havana) plants were exposed to supplemental UV centred at 318 nm and corresponding to 13.6 kJ m À2 d À1 biologically effective UV-B (280e315 nm) radiation. After 6 days this treatment decreased photosynthesis by 30%. Leaves responded by a large increase in UV-absorbing pigment content and antioxidant capacities. UV-stimulated defence against ROS was strongest in chloroplasts, since activities of plastid enzymes FeSOD and APX had larger relative increases than other, non-plastid specific SODs or peroxidases. In addition, non-enzymatic defence against hydroxyl radicals was doubled in UV treated leaves as compared to controls. In UV treated leaves, the extent of activation of ROS neutralizing capacities followed a peroxidases > hydroxyl-radical neutralization > SOD order. These results suggest that highly effective hydrogen peroxide neutralization is the focal point of surviving UV-inducible oxidative stress and argue against a direct signalling role of hydrogen peroxide in maintaining adaptation to UV, at least in laboratory experiments.

Computer analysis of digital photographic images provides fast, high-throughput screening of leaf pigmentation. Pixel-by-pixel conversion of red, green, blue (RGB) parameters to hue, saturation, value (HSV) showed that Hue values were proportional to total chlorophyll, offering an alternative to photometric analysis of leaf extracts. This is demonstrated using tobacco leaves with various chlorophyll contents due to senescence but shows the possibility of applications in studies of stress conditions accompanied by chlorophyll loss.

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The effect of Medicago sativa (alfalfa) ferritin gene (MsFer) on abiotic stress tolerance was tested using transgenic Vitis berlandieri 9 Vitis rupestris cv. 'Richter 110' grapevine rootstock lines. Leaf discs from transgenic plants maintained higher photosynthetic activity after NaCl, tert-butyl-hydroperoxide (t-BHP) or paraquat treatment than control ones. These results indicate that the increased production of ferritin significantly improved abiotic stress tolerance in transgenic grapevine plants.