Lubovská Z., Dobrá j., Štorchová H., Wilhelmová N., Vaňková R.
JOURNAL OF PLANT PHYSIOLOGY
171:
1625- 1633,
2014
Klíčová slova:
Abstrakt:
Cytokinins (CKs) as well as the antioxidant enzyme system (AES) play important roles in plant stress
responses. The expression and activity of antioxidant enzymes (AE) were determined in drought,
heat and combination of both stresses, comparing the response of tobacco plants overexpressing the
main cytokinin degrading enzyme, cytokinin oxidase/dehydrogenase, under the control of root-specific
WRKY6 promoter (W6:CKX1 plants) or constitutive promoter (35S:CKX1 plants) and the corresponding
wild-type (WT). Expression levels as well as activities of cytosolic ascorbate peroxidase, catalase 3,
and cytosolic superoxide dismutase were low under optimal conditions and increased after heat and
combined stress in all genotypes. Unlike catalase 3, two other peroxisomal enzymes, catalase 1 and
catalase 2, were transcribed extensively under control conditions. Heat stress, in contrast to drought or
combined stress, increased catalase 1 and reduced catalase 2 expression in WT and W6:CKX1 plants. In
35S:CKX1, catalase 1 expression was enhanced by heat or drought, but not under combined stress conditions.
Mitochondrial superoxide dismutase expression was generally higher in 35S:CKX1 plants than in
WT. Genes encoding for chloroplastic AEs, stromatal ascorbate peroxidase, thylakoidal ascorbate peroxidase
and chloroplastic superoxide dismutase, were strongly transcribed under control conditions. All
stresses down-regulated their expression in WT and W6:CKX1, whereas more stress-tolerant 35S:CKX1
plants maintained high expression during drought and heat. The achieved data show that the effect of
down-regulation of CK levels on AES may be mediated by altered habit, resulting in improved stress tolerance,
which is associated with diminished stress impact on photosynthesis, and changes in source/sink
relations.
Autoři z ÚEB: Helena Štorchová,
Radomíra Vanková,
Naďa Wilhelmová
Čeština
English