Response of antioxidant enzymes to transfer from elevated carbon dioxide to air and ozone fumigation, in the leaves and roots of wild‐type and a catalase‐deficient mutant of barley

Abstract

A catalase‐deficient mutant (RPr 79/4) and the wild‐type (cv. Maris Mink) barley (Hordeum vulgare L.) counterpart, were grown for 3 weeks in high CO2 (0.7%) and then transferred to air and ozone (120 nl 1−1) in the light and shade for a period of 4 days. Leaves and roots were analysed for catalase (CAT, EC 1.11.1.6), superoxide dismutase (SOD, EC 1.15.1.1) and glutathione reductase (GR, EC 1.6.4.2) activities. CAT activity in the leaves of the RPr 79/4 catalase‐deficient mutant was around 5‐10% of that determined in Maris Mink, but in the roots, both genotypes contained approximately the same levels of activity. CAT activity in Maris Mink increased in the leaves after transferring plants from 0.7% CO2 to air or ozone, reaching a maximum of 5‐fold, after 4 days in shade and ozone. For the catalase‐deficient mutant, only small increases in CAT activity were observed in light/air and light/ozone treatments. In the roots, CAT activity decreased consistently in both genotypes, after plants were transferred from 0.7% CO2. The total soluble SOD activity in the leaves and roots of both genotypes increased after plants were transferred from 0.7% CO2. The analysis of SOD isolated from leaves following non‐denaturing PAGE, revealed the presence of up to eight SOD isoenzymes classified as Mn‐SOD or Cu/Zn‐SODs; Fe‐SOD was not detected. Significant changes in Mn‐ and Cu/Zn‐SOD isoenzymes were observed; however, they could not account for the increase in total SOD activity. In leaves, GR activity also increased in Maris Mink and RPr 79/4, following transfer from 0.7% CO2; however, no constant pattern could be established, while in roots, GR activity was reduced after 4 days of the treatments. The data suggest that elevated CO2 decreases oxidative stress in barley leaves and that soluble CAT and SOD activities increased rapidly after plants were transferred from elevated CO2, irrespective of the treatment (light, shade, air or ozone).

Quantitative expression analysis of drought responsive genes in clones of Hevea with varying levels of drought tolerance

“…They are known to remove H 2 O 2 produced in the peroxisomes by photorespiration (Noctor et al 2000), β-oxidation of fatty acids and other enzyme systems such as xanthine oxidase (XOD) coupled to SOD (Sharma et al 2012). CAT activity has also been found to decrease under conditions that suppress photorespiration, such as elevated CO 2 (Azevedo et al 1998) and high light intensities (Shang and Feierabend 1999). The reduction in catalase expression found in all the clones in this study need to be further investigated.…”

Change in Physiological Features in Ryegrass Biotypes in Competition With Soybean Due Resistance to Glyphosate

“…The APX and CAT activities were determined according to (Azevedo et al, 1998), and the methodology for determining SOD was adapted from Giannopolitis and Ries (1977), for these analyzes was used in the sample extraction of 0.2 g of plant material.…”

Enxofre na atenuação dos efeitos tóxicos do cádmio no capim-tanzânia

“…A revelação do gel seguiu o método descrito por Beauchamp e Fridovich (1971), com modificações de Azevedo et al (1998) …”

“…A atividade em espectrofotometria foi determinada de acordo com o método descrito por Kraus, McKersie e Fletcher (1995), com modificações de Azevedo et al (1998). O meio de reação continha 1 mL da solução de H 2 O 2 a 30 mmol L -1 em tampão fosfato de potássio a 100 mmol L -1 (pH 7,5).…”

“…A atividade da GR foi determinada por espectrofotometria e PAGE, de acordo com o método descrito por Smith, Vierheller e Thorne (1988), com modificações de Azevedo et al (1998), no qual 1 mL do meio de reação continha DTNB a 1 mmol L -1 ; GSSG a 1 mmol L -1 , NADPH a 0,1 mmol L -1 e 30 µL de amostra proteica em solução tampão fosfato de potássio a 100 mmol L -1 (pH 7,5). A leitura foi realizada durante 1 minuto a 412 nm.…”