PubMed · 13253134
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C S DAY. 1955. Cornu cutaneum.. https://pubmed.ncbi.nlm.nih.gov/13253134/
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The response of woody plant tissues to freezing temperature has evolved into two distinct behaviors: an avoidance strategy, in which intracellular water supercools, and a freeze-tolerance strategy, where cells tolerate the loss of water to extracellular ice. Although both strategies involve extracellular ice formation, supercooling cells are thought to resist freeze-induced dehydration. Dehydrin proteins, which accumulate during cold acclimation in numerous herbaceous and woody plants, have been speculated to provide, among other things, protection from desiccative extracellular ice formation. Here we use Cornus as a model system to provide the first phylogenetic characterization of xylem freezing behavior and dehydrin-like proteins. Our data suggest that both freezing behavior and the accumulation of dehydrin-like proteins in Cornus are lineage related; supercooling and nonaccumulation of dehydrin-like proteins are ancestral within the genus. The nonsupercooling strategy evolved within the blue- or white-fruited subgroup where representative species exhibit high levels of freeze tolerance. Within the blue- or white-fruited lineage, a single origin of dehydrin-like proteins was documented and displayed a trend for size increase in molecular mass. Phylogenetic analyses revealed that an early divergent group of red-fruited supercooling dogwoods lack a similar protein. Dehydrin-like proteins were limited to neither nonsupercooling species nor to those that possess extreme freeze tolerance.
Dehydrins are proteins associated with conditions affecting the water status of plant cells, such as drought, salinity, freezing and seed maturation. Although the function of dehydrins remains unknown, it is hypothesized that they stabilize membranes and macromolecules during cellular dehydration. Red-osier dogwood (Cornus sericea L.), an extremely freeze-tolerant woody plant, accumulates dehydrin-like proteins during cold acclimation and the presence of these proteins is correlated with increased freeze tolerance (Karlson 2001, Sarnighausen et al. 2002, Karlson et al. 2003). Our objective was to determine the location of dehydrins in cold-acclimated C. sericea stems in an effort to provide insight into their potential role in the freeze tolerance of this extremely cold hardy species. Abundant labeling was observed in the nucleus and cytoplasm of cold-acclimated C. sericea stem cells. In addition, labeling was observed in association with plasmodesmata of cold-acclimated vascular cambium cells. The unique association of dehydrin-like proteins with plasmodesmata has not been reported previously.
OBJECTIVE: To set up the optimums of tissue culture for Cornus officinalis. METHOD: A section of stems of the fine varieties of Cornus officinalis were strictly sterilized, cultivated and geminated in medium with addition of different kinds of hormone. RESULT AND CONCLUSION: The WPM medium with 6-BA 2.0 mg.L-1 + ZT 0.1 mg.L-1 + NAA 0.1 mg.L-1 was the optimum medium for the multiplication of adventitious buds. The WPM medium with 6-BA 1.0 mg.L-1 + ZT 0.1 mg.L-1 + GA3 0.5 mg.L-1 + NAA 0.1 mg.L-1 was the optimum medium for cultivation in strength. The plantlet could root well in 1/2 MS medium with IBA 1.0 mg.L-1 + 6-BA 0.1 mg.L-1.