ISHS Acta Horticulturae 168: II Symposium on Winter Hardiness in Woody Perennials
VARIATION OF PROTEINS, NUCLEIC ACIDS AND CARBOHYDRATES IN THE ANNUAL CYCLE DIAPENSIA LAPPONICA L |
| Author: | S. Pihakaski |
| Abstract:
The cold hardening processes of several plants have often been reported to be associated with rhythmic annual changes in certain cellular compounds, such as proteins, nucleic acids and carbohydrates. In the present study changes in those substances were studied in a subarctic chionophobous evergreen plant, Diapensia Lapponica L. during three successive years. All determinations were carried out from green parts of Diapensia shoots. One finding was that the protein level rose during the early autumn, and remained high until midwinter. Soluble proteins, which are often mentioned as increasing in parallel with the development of the cold hardening stage of plant cells, also showed a tendency to increase in Diapensia shoot tissues in September, as well as in early May, preceeding the growth period. The considerable and rapid increases in total DNA and RNA which took place in the early autumn indicated the necessity of the synthesis of these compounds for the cold hardening machinery. The RNA level was also high during the decrease in cold resistance (March-April) when RNA was built up and evidently stored for the intense protein synthesis taking place some weeks later. Changes in carbohydrates during the hardening stage of Diapensia were rather similar to those found in cloudberry cells. In the middle of September starch was hydrolyzed while soluble carbohydrates such as sugars increased very rapidly. The level of sugars remained high for the whole winter in hardened tissues, but starch was low and mostly absent in mesophyll cells of Diapensia leaves, as also reported in an electronmicroscopical study. | |
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