ABSTRACT
The freezing tolerance of Arabidopsis thaliana (L.) Heynh. was studied in relation to functioning of the ethylene signaling pathway. Constitutive freezing tolerance was compared in wild-type plants (ecotype Col-0) and ethylene-insensitive mutants etr1-1 and ein2-1. For the first time it was established that the ethylene-insensitive mutants had a 25-30% lower net photosynthesis rate, a decreased content of soluble sugars, and, as a result, a lower freezing tolerance. Our work provides evidence that the perception and transduction of ethylene signal are necessary for constitutive tolerance of Arabidopsis to low temperature.
Subject(s)
Arabidopsis Proteins/genetics , Arabidopsis/genetics , Arabidopsis/physiology , Ethylenes/metabolism , Freezing , Mutation , Receptors, Cell Surface/genetics , Arabidopsis/cytology , Arabidopsis/metabolism , Signal Transduction/genetics , Time FactorsABSTRACT
The content of saccharides and phenolic compounds (including flavonoids and lignin) and the activity of L-phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) were determined in leaves and tillering nodes of winter wheat Triticum aestivum L.) cultivars Inna and Moskovskaya 39, differing in the level of frost resistance. These parameters were determined in three groups of plants--control, hardened, and treated with synthetic antioxidants (ambiol and amerol 2000). Cold hardening increased accumulation of primary and secondary metabolites in tissues but decreased the enzyme activity. Treatment with antioxidants also increased the content of saccharides and phenolic compounds (primarily flavonoids) and PAL activity. These changes were more pronounced in cultivar Inna, which is less frost resistant than Moskovskaya 39.
Subject(s)
Acclimatization/drug effects , Antioxidants/pharmacology , Phenylalanine Ammonia-Lyase/metabolism , Plant Leaves/enzymology , Plant Proteins/metabolism , Triticum/enzymology , Acclimatization/physiology , Flavonoids/metabolism , Lignin/metabolism , Seasons , Species SpecificityABSTRACT
Long-term studies of the cytoplasm-nucleus interactions in alloplasmic hybrids with the nucleus of Triticum aestivum functioning in the alien cytoplasm of Aegilops ovata are reviewed. The interaction of heterologous genome and cytoplasm affects the balanced mechanisms of developmental control of the parental forms. The changes are observed at all levels of both physiological and morphological processes. Alloplasmic wheats produced by backcrossing represent a novel type of synthetic plant different from the T. aestivum type and of great interest to breeders.
Subject(s)
Cell Nucleus/metabolism , Chimera/growth & development , Cytoplasm/metabolism , Poaceae/cytology , Triticum/physiology , Chimera/metabolism , Cold Temperature , Morphogenesis , Triticum/geneticsABSTRACT
Cycloheximide in the concentration inhibiting protein synthesis and frost resistance of plants proved to prevent formation of cell and chloroplast structures specific for the plants adapted to frost. Important role of structural rearrangement of the cells during hardening preventing intracellular ice nucleation is proposed.
