UV‐B response of cucumber seedlings grown under metal halide and high pressure sodium/deluxe lamps

Abstract

1993. UV-B response of cucumber seedlings grown under metal halide and high pressure sodium/ deluxe lamps. -Physiol. Plant. 88: 350-358.UV-B-sensitive (Poinsett) and -insensitive (Ashley) cuhivars of cucumber {Cucumts sativus L.) were grown in growth chambers al 600 nmol m -s ' of photosynthetically active radiation provided by metal halide (MH) or high pressure sodium/deluxe (HPS/DX) lamps. Plants were irradiated 15 days from seeding for 6 h per day under 18.2 kJ m -day"' of biologically effective UV-B (UV-Bj^) radiation. One of the most pronounced effects of UV-B was a 27 to 78% increase in phenylalanine ammonialyase (PAL) activity. UV-B also increased total polyamines. Catalase and superoxide dismutase varied greatly in their response to UV-B. There were no interactive effects on PAL or catalase activity, or total polyamines. There was a UV x PAR source interaction for superoxide dismutase activity. UV-B increased chlorosis and decreased height, dry weight and leaf area. Stem elongation, biomass production, leaf enlargement and chlorosis were greater under HPS/DX lamps than under MH lamps. Chlorosis was greater in Poinsett than in Ashley and in lower leaves than in upper ones. Aside from chlorosis, there were no interactive effects of UV-B, PAR source or cultivar on any of the growth parameters measured, suggesting that the growth response of cucumber seedlings to UV-B is unaffected by PAR source or cuitivar. Similarly, except for SOD activity, the biochemical response to UV-B was also nol influenced by PAR source or cultivar.

Anti-oxidant modulation in response to gamma radiation induced oxidative stress in developing seedlings of Psoralea corylifolia L.

“…Minimum enhancement in SOD (8.36%), APX (10.01%) and GR (5.98%) activity was observed at flowering stage in plants raised from seeds exposed to 2.5 kGy. Increase in reactive oxygen species, and/or induced activities of peroxidase related enzymes by ionizing radiation have been observed in several species including Cucumber (Krizek et al, 1993), sugar beet (Panagopoulos et al, 1990) and cyanobacterium Anacystis nidulans (Shibata et al, 1991). According to Karpinski et al (1997), the APX activity induction in Arabidopsis submitted to oxidative stress conditions such as high light intensity, takes place by induction of APX1 and APX2 gene transcription.…”

Constitutive Expression of a Tomato Small Heat Shock Protein Gene LeHSP21 Improves Tolerance to High-Temperature Stress by Enhancing Antioxidation Capacity in Tobacco

“…It is well known that heat stress can generate oxidative stress through the formation of reactive oxygen species (ROS) (Krizek et al 1993;Strid 1993), which in turn causes the enhancement of lipid and protein oxidation (Kramer et al 1991;Landry et al 1995). ROS are products of chloroplast and mitochondrial metabolism produced during abiotic stresses that cause membrane damage (Apse and Blumwald 2002;Apel and Hirt 2004).…”

Increased antioxidant activity in Cassia seedlings under UV-B radiation

“…The UV-B enhancement of CAT and POX activities which are both responsible for detoxification of H 2 O 2 are probably equally important in the detoxification of H 2 O 2 generated by SOD in Cassia seedlings. Increases in activities of peroxidases by UV-B radiation have been observed in several species including Cassia species (Agarwal and Pandey 2003b), Arabidopsis thaliana (Rao et al 1996), cucumber (Krizek et al 1993), sugarbeet (Panagopoulos et al 1990), and potato (Santos et al 2004). In addition, the metabolism of phenolic compounds also includes the action of oxidative enzymes such as POX and PPO, which catalyze the oxidation of phenols to quinones (Thypyapong et al 1995).…”