- Email: [email protected]
Supercooling in hardwood xylem
552
ABSTRACTS-ELEVENTH
to that of the young leaves after thawing. The check samples did not accumulate proline during hardening. In the sample prepared at 4°C in darkness before freezing, the proline increased in the young leaves during freezing and decreased in the leaves at the base. However, the proline content of the young leaves remained low. The proline, which increased on thawing in all the samples as did the other amino acids, probably proved protein hydrolysis of the dead plants. The hardened plants accumulated soluble glucides m the course of the hardening. In the young leaves these glucides decreased during freezing and thawing in the same way as observed in the older leaves rewarmed at 4°C; on the other hand the glucides which had decreased during freezing increased if the rewarming took place at 18°C in the presence or absence of light. In the check samples poor in glucides, these decrease during freezing. So these experiments seem to confirm that there is a link between proline content, content of soluble glucides and frost hardiness. Nevertheless it is odd that if the hardening is transmitted from the leaves at the base to the young leaves in an acropetal way as was shown by former experiments, it seems nevertheless that there was translocation or induction of the protective substances in an inverse direction in the hardened plants in the course of thawing.
48. Long-
and Short-Term Hardiness in Pinus silvestris. J. C. A. h4. BERVAES,* P. J. C. KUJPER, AND A. KYLIN* (Laboratory of Plant Physiological Research, Wageningen, Holland, Department of Plant Physiology, Royal Vetenary and Agricultural University, Copenhagen, Denmark ).
Pine plants which had been grown in the greenhouse and transported to outside (’ -10°C) “remembered” something of their earlier growing circumstances during a long period! They differed from the plants continuously grown outside in the Zeuel of hardiness, although changes in temperature caused similar fluctuations in hardiness of both groups. Factors affecting the changes in short term and those affecting the level of hardiness will he discussed. Emphasis is paid on chloroplest-nlcmhrane lipid composition and dark .AT?‘ase activity (Ph!/sbl. Plant. 27, 178-181 and 231-235). In the short term adaptation the most striking observation is an internal rearrangement of the diterpenedicarhoxylic acid monomethylester fraction.
ANNUAL
MEETING
AND A. G. JOHNSON" (Department of Horticultural Science, University of Minnesota, St. Paul, Minnesota 55101). Introduced by A. P. hlacKenzie. Reviews on cold hardiness recognize supercooling as a potential mechanism of frost avoidance, hut it has been difficult to find examples in the plant kingdom. Overwhehning floral primordia in two genera and living xylem cells of apple and blueberry are tissues reported to supercool, In this paper, supercooling of living xylem tissue to the homogeneous nucleation temperature ( “C) is found to he the frost avoidance mechanism in xylem of the following 24 woody plant species. IugZans nigra L. ( -4l), Cu ya ouuta (Mill.) K. Koch. ( -43), Carya cordifo~mis (Wang.) K. Koch. (-45), Carpinus curoliniunu Walt. (-42), Ostrya cirginicna (Mill.) K. Koch. (-41), Bet& Zutea Michx: ( -44), Quercus alho L. ( -41), (ktercus rubru L. ( -4l), Quercfls mucrocurpa Michx. ( -43), Fugus grundifoliu Ehrh. (-41}, Gleditsiu triacanthos L. (-41), Ulmrrs thomasii Sang. ( -43), WZmus americuna L. (-43!, Plotunus occitlentolis L. ( -41)) Prunus serotina Ehrh. ( -42)) Cercis canatlensis L. (-41), ACW rubrum L. ( -45), Cornus rucemosa Lam. (-41), Cornus ulternifolia L. ( --41), Fraxinus pennsyloanica Marsh. (-41), Frusinus americanu L,. ( -42), and Frurinus nigm Marsh. ( -47). When these supercooled tissues froze, death always occurred. These species depend on supercooling as a frost avoidance mechanism and are not native or even cultivated in regions routinely subjected to temperatures slightly below the homogeneous nucleation temperature, about -40°C. Such regions include most of Canada and parts of the Northern United States.
50. The Simukution of Osmotic Stresses of PZunt Cells by Lipid Liposome fifembrune Systems. I>. SIMINOVITCH AND D. CHAPMAN* (CBRI, Canada Agriculture, Dept. of Chemistry, IJniversity England).
Ottawa and of Sheffield,
Following up on earlier studies on effects of freezing on liposome artificial membrane systems made up entirely of pure lipids, a study has beru made of the effects of osmotic tlchydration lry strong solutions on similar systems. Using egg yolk lecithin liposomes into which chromate marker had been incorporated, and subjecting these Iiposomes to solutions of mixed sodium and calcium chloride of progressively increasing mohuity, followed by rchydration it7 the original dilute potassium chloride in which the liposomcs
ABSTRACTS-ELEVENTH
to that of the young leaves after thawing. The check samples did not accumulate proline during hardening. In the sample prepared at 4°C in darkness before freezing, the proline increased in the young leaves during freezing and decreased in the leaves at the base. However, the proline content of the young leaves remained low. The proline, which increased on thawing in all the samples as did the other amino acids, probably proved protein hydrolysis of the dead plants. The hardened plants accumulated soluble glucides m the course of the hardening. In the young leaves these glucides decreased during freezing and thawing in the same way as observed in the older leaves rewarmed at 4°C; on the other hand the glucides which had decreased during freezing increased if the rewarming took place at 18°C in the presence or absence of light. In the check samples poor in glucides, these decrease during freezing. So these experiments seem to confirm that there is a link between proline content, content of soluble glucides and frost hardiness. Nevertheless it is odd that if the hardening is transmitted from the leaves at the base to the young leaves in an acropetal way as was shown by former experiments, it seems nevertheless that there was translocation or induction of the protective substances in an inverse direction in the hardened plants in the course of thawing.
48. Long-
and Short-Term Hardiness in Pinus silvestris. J. C. A. h4. BERVAES,* P. J. C. KUJPER, AND A. KYLIN* (Laboratory of Plant Physiological Research, Wageningen, Holland, Department of Plant Physiology, Royal Vetenary and Agricultural University, Copenhagen, Denmark ).
Pine plants which had been grown in the greenhouse and transported to outside (’ -10°C) “remembered” something of their earlier growing circumstances during a long period! They differed from the plants continuously grown outside in the Zeuel of hardiness, although changes in temperature caused similar fluctuations in hardiness of both groups. Factors affecting the changes in short term and those affecting the level of hardiness will he discussed. Emphasis is paid on chloroplest-nlcmhrane lipid composition and dark .AT?‘ase activity (Ph!/sbl. Plant. 27, 178-181 and 231-235). In the short term adaptation the most striking observation is an internal rearrangement of the diterpenedicarhoxylic acid monomethylester fraction.
ANNUAL
MEETING
AND A. G. JOHNSON" (Department of Horticultural Science, University of Minnesota, St. Paul, Minnesota 55101). Introduced by A. P. hlacKenzie. Reviews on cold hardiness recognize supercooling as a potential mechanism of frost avoidance, hut it has been difficult to find examples in the plant kingdom. Overwhehning floral primordia in two genera and living xylem cells of apple and blueberry are tissues reported to supercool, In this paper, supercooling of living xylem tissue to the homogeneous nucleation temperature ( “C) is found to he the frost avoidance mechanism in xylem of the following 24 woody plant species. IugZans nigra L. ( -4l), Cu ya ouuta (Mill.) K. Koch. ( -43), Carya cordifo~mis (Wang.) K. Koch. (-45), Carpinus curoliniunu Walt. (-42), Ostrya cirginicna (Mill.) K. Koch. (-41), Bet& Zutea Michx: ( -44), Quercus alho L. ( -41), (ktercus rubru L. ( -4l), Quercfls mucrocurpa Michx. ( -43), Fugus grundifoliu Ehrh. (-41}, Gleditsiu triacanthos L. (-41), Ulmrrs thomasii Sang. ( -43), WZmus americuna L. (-43!, Plotunus occitlentolis L. ( -41)) Prunus serotina Ehrh. ( -42)) Cercis canatlensis L. (-41), ACW rubrum L. ( -45), Cornus rucemosa Lam. (-41), Cornus ulternifolia L. ( --41), Fraxinus pennsyloanica Marsh. (-41), Frusinus americanu L,. ( -42), and Frurinus nigm Marsh. ( -47). When these supercooled tissues froze, death always occurred. These species depend on supercooling as a frost avoidance mechanism and are not native or even cultivated in regions routinely subjected to temperatures slightly below the homogeneous nucleation temperature, about -40°C. Such regions include most of Canada and parts of the Northern United States.
50. The Simukution of Osmotic Stresses of PZunt Cells by Lipid Liposome fifembrune Systems. I>. SIMINOVITCH AND D. CHAPMAN* (CBRI, Canada Agriculture, Dept. of Chemistry, IJniversity England).
Ottawa and of Sheffield,
Following up on earlier studies on effects of freezing on liposome artificial membrane systems made up entirely of pure lipids, a study has beru made of the effects of osmotic tlchydration lry strong solutions on similar systems. Using egg yolk lecithin liposomes into which chromate marker had been incorporated, and subjecting these Iiposomes to solutions of mixed sodium and calcium chloride of progressively increasing mohuity, followed by rchydration it7 the original dilute potassium chloride in which the liposomcs