The influence of low-temperature on the photochemical activity of chloroplasts and activity of antioxidant enzymes in maize leaves

摘要

The effects of low growth temperature on the activities of photosystems (PS) 1 and 2 and antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT) in leaves of various maize inbred and hybrid genotypes (parental lines, F1 hybrids, F2 and backcross generations) were investigated. Considerable decrease of the PS 2 activity (contrary to the activity of PS 1) due to low-temperature stress was observed in the majority of genotypes/generations examined. The GR, APX and SOD activities markedly increased due to chilling, whereas the activity of CAT showed lesser changes which depended on the genotype/generation analysed. The higher susceptibility of the inbred line 2013 to low temperature was transmitted to further generations in case this line was used as the maternal parent. The intraspecific variability in photosynthetic and antioxidant parameters was caused particularly by the dominance (negative or positive), however, the level of the expression of this effect often changed after low-temperature stress and was probably the cause of the increase in the positive F1 heterosis observed in this case. Other genetic effects (e.g. the additivity, and particularly the additive or dominant maternal effects) were also found to contribute to the intraspecific variability in parameters analyzed. The dominant maternal effects possibly played an important role in maintaining positive heterosis in F2 generation. Additional key words additivity - cold stress - dominance - heterosis - intraspecific variability - maternal effects - photosynthesis - photosystems 1 and 2 Acknovledgements: The authors are grateful to Dr. J. Poruba from CEZEA Breeding Station for the supply of maize kernels and to our graduate student K. Langerová for the help with experiments. We appreciate the participation of Drs. D. Procházková and Z. Mytinová in assays of the enzyme activities. This study was supported by Grants No. 522/01/0846 of the Grant Agency of the Czech Republic and No. 0021620858 of the Ministry of Education, Youth and Sports of the Czech Republic.