Chilling stress and oxygen metabolizing enzymes in Zea mays and Zea diploperennis*

Abstract

Abstract. The activities of five active‐oxygen scavenging enzymes were compared for cold‐lability and three were compared for chilling induction in two Zea genotypes of contrasting susceptibility to photoinhibition during chilling. Activities of superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4), dehydroascorbate reductase (DHAR, EC 1.8.5.1), and glutathione reductase (GTR, EC 1.6.4.2) in leaf extracts from plants grown without chilling stress were assayed at 19°C and 5°C. Enzymes from the chilling‐susceptible Z. Mays cv. LG11 had lower specific activities at 5°C than did enzymes from the chilling‐tolerant Z. diploperennis, except for MDHAR where no significant differences were observed. The activities of SOD and APX from Z. diploperennis were double those of Z. mays at both assay temperatures. Monodehydroa‐scrobate reductase and glutathione reductase activities in both species were reduced by 63–78% at a 5°C assay temperature. The dehydroascorbate reductase (DHAR) showed the greatest low‐temperature lability losing 96% (Z. diploperennis) and 100% (Z. mays) of its activity at 5°C. To examine possible chilling‐induced changes in levels of enzyme activity, plants of both Zea genotypes were transferred to growth chambers at 10°C at moderate light intensities. Glutathione reductase activity was found to increase within 24h in Z. diploperennis, but it decreased slightly in Z. mays. MDHAR activity decreased by 50% in Z. diploperennis but showed only a transient increase in activity in Z. mays.

Responses of antioxidant enzymes and compounds in strawberry (Fragaria×ananassa‘Toyonaka’) to cold stress

“…This oxidative stress is probably owing to an increase in the accumulation of ROS, particularly O 2 -and h 2 O 2 (Foyer & Noctor 2005). Lipid peroxidation and consequent ROS production is mediated by alternate O 2 reduction, therefore this compound promotes the oxidative damage in plants under cold stress as reported by several researchers (Jahnke et al 1991;hodges et al 1997;Li et al 2000;Kang & Saltveit 2001). in the present study, the higher O 2 -and h 2 O 2 levels in the leaves of seedlings exposed to 0°C, 4°C, 10°C, when compared with the control, reflected the degree of oxidative stress during severe cold stress (Fig.…”

Cold stress affects antioxidative response and accumulation of medicinally important withanolides in Withania somnifera (L.) Dunal

“…Glutathione reductase (GR; EC 1.6.4.2) activity assays were performed at RT in 50 mM potassium phosphate buffer (pH 7.8) following the method of Jahnke et al (1991). Tissue extract (20 l) placed in a buffer containing 1 mM GSSG, 1 mM EDTA and 0.1 mM NADPH was incubated at 37 • C for 30 min.…”

Regulation of pea cytosolic ascorbate peroxidase and other antioxidant enzymes during the progression of drought stress and following recovery from drought

“…Environmental stresses such as drought (Mittler and Zilinskas, 1992;Smirnoff and Colombe, 1988;Tanaka et al, 1990); high light intensity (Gillham and Dodge, 1987); low temperature (Jahnke et a/., 1991); and exposure to various chemicals including paraquat (Melhorn, 1990;Mittler and Zilinskas, 1992) and norflurazon (Thomsen et al, 1992), or air pollutants such as ozone (Melhorn, 1990;Tanaka et al, 1985), have been correlated with increased activity of antioxidant enzymes.…”