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2.
Adv Space Res ; 27(5): 957-60, 2001.
Article in English | MEDLINE | ID: mdl-11596639

ABSTRACT

We examined whether sedimentable amyloplasts act as statolith in the perception of gravity in woody stems using the elongated internodes of Japanese cherry (Prunus jamasakura Sieb. ex Koidz.). In the internode of the seedlings grown on earth, amyloplasts were found sedimented at the distal end of each cell of the endodermal starch sheath tissue. In the internode grown on three-dimensional (3-D) clinostat, amyloplasts were dispersed throughout the cell matrix in the endodermal starch sheath tissue. After changing the positions of the internode from vertical to horizontal, re-sedimentation of amyloplasts toward the direction of gravity was completed in 1h, whereas the bending of the internode was observed after 12 days. We propose that sedimentable amyloplasts in the endodermal starch sheath cells may play a role in gravity perception leading to secondary xylem formation in the secondary thickening growth and eccentric growth in gravi-bending of tree stems.


Subject(s)
Gravity Sensing/physiology , Plant Stems/physiology , Plastids/physiology , Prunus/physiology , Starch/physiology , Gravitation , Microscopy, Confocal , Plant Stems/growth & development , Plant Stems/ultrastructure , Plastids/ultrastructure , Prunus/growth & development , Prunus/ultrastructure , Rotation
3.
Tree Physiol ; 21(16): 1223-9, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11600344

ABSTRACT

We compared effects of ambient (360 vpm) and elevated (720 vpm) carbon dioxide concentration ([CO2]) and high and low nutrient supply rates on stem growth, annual ring structure and tracheid anatomy of Siberian larch (Larix sibirica Ledeb.) seedlings over two growing seasons. Elevated [CO2] had no significant effect on either stem height or diameter growth; however, both stem height and diameter growth were enhanced by the high nutrient supply rate, and these increases were stimulated by elevated [CO2]. Elevated [CO2] tended to increase the width of the annual xylem ring, the number of cells in a radial file spanning the ring, and tracheid lumen diameter, whereas it tended to reduce cell wall thickness, although there were no statistically significant CO2 effects on tracheid anatomy. Changes in tracheid cell morphology seemed to be dependent on changes in shoot elongation rates.


Subject(s)
Larix/growth & development , Trees/growth & development , Carbon Dioxide/physiology , Larix/physiology , Plant Shoots/growth & development , Plant Shoots/physiology , Plant Stems/growth & development , Plant Stems/physiology , Trees/physiology
4.
Planta ; 212(5-6): 684-91, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11346941

ABSTRACT

A study was made of cambial activity, the localization of storage starch around the cambium, and the localization and occurrence of microtubules in cambial cells from dormancy to reactivation in locally heated (22-26 degrees C) stems of the evergreen conifer Abies sachalinensis. Heating induced localized reactivation of the cambium in the heated portions of the stem. Erect ray cambial cells resumed cell division 1 d prior to the reactivation of fusiform cambial cells and procumbent ray cambial cells. The re-initiation of the division of fusiform cambial cells occurred first on the phloem side. During the heat treatment, the amount of storage starch decreased in procumbent ray cambial cells and in the phloem parenchyma adjacent to the cambium but increased in fusiform cambial cells. Preprophase bands of microtubules, spindle microtubules and phragmoplast microtubules were observed both in erect ray cambial cells and in procumbent ray cambial cells. By contrast, no evidence of the presence of such preprophase bands of microtubules was detected in fusiform cambial cells. The results suggest that the localized heating of stems of evergreen conifers might provide a useful experimental model system for studies of the dynamics of cambial reactivation in intact trees.


Subject(s)
Cycadopsida/physiology , Meristem/physiology , Cycadopsida/cytology , Hot Temperature , Meristem/cytology , Microtubules/physiology , Microtubules/ultrastructure , Mitosis/physiology , Models, Biological , Organelles/metabolism , Starch/metabolism , Trees/cytology , Trees/physiology , Weather
5.
Plant Physiol ; 121(3): 897-904, 1999 Nov.
Article in English | MEDLINE | ID: mdl-10557238

ABSTRACT

For an examination of the progression of cavitation in large-diameter earlywood vessels of a deciduous ring-porous tree, potted saplings of Fraxinus mandshurica var japonica Maxim. were frozen and then thawed. The changes in the amount and distribution of water in the lumina of the current year's earlywood vessels during the course of the freezing and thawing were visualized by cryo-scanning electron microscopy. When samples were frozen, most of the current year's earlywood vessels were filled with water. After the subsequent thawing, the percentage of cavitated current-year earlywood vessels gradually increased with time. All of the current year's earlywood vessels were cavitated within 24 h, and only limited amounts of water remained in the lumina of earlywood vessels. Similar cavitation of earlywood vessels was observed after thawing of frozen, excised stem pieces. In contrast, many vessels of the current year's latewood retained water in the lumina during freezing and thawing. These observations indicate that the cavitation of the current year's earlywood vessels is not produced during freezing but progresses during rewarming after freezing in F. mandshurica var japonica.

6.
Plant Physiol ; 117(4): 1463-71, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9701601

ABSTRACT

Xylem cavitation in winter and recovery from cavitation in the spring were visualized in two species of diffuse-porous trees, Betula platyphylla var. japonica Hara and Salix sachalinensis Fr. Schm., by cryo-scanning electron microscopy after freeze-fixation of living twigs. Water in the vessel lumina of the outer three annual rings of twigs of B. platyphylla var. japonica and of S. sachalinensis gradually disappeared during the period from January to March, an indication that cavitation occurs gradually in these species during the winter. In April, when no leaves had yet expanded, the lumina of most of the vessels of both species were filled with water. Many vessel lumina in twigs of both species were filled with water during the period from the subsequent growth season to the beginning of the next winter. These observations indicate that recovery in spring occurs before the onset of transpiration and that water transport through twigs occurs during the subsequent growing season. We found, moreover, that vessels repeat an annual cycle of winter cavitation and spring recovery from cavitation for several years until irreversible cavitation occurs.

7.
Plant Mol Biol ; 32(6): 1209-13, 1996 Dec.
Article in English | MEDLINE | ID: mdl-9002623

ABSTRACT

Winged bean Kunitz chymotrypsin inhibitor (WCI) accumulates abundantly in seeds and tuberous roots, and small amounts of the WCI protein and mRNA can also be detected in stems. In this study, we analyzed the localization of the WCI protein in stems of winged bean. The results demonstrated that the WCI protein was localized in sieve tubes. Furthermore, we showed that the 5' region of the WCI-3b gene, which exhibited strong transcriptional activity in developing seeds, also promoted transcription of a reporter gene in the phloem of stems of transgenic tobacco.


Subject(s)
Fabaceae/genetics , Genes, Plant , Plant Proteins , Plant Stems/genetics , Plants, Medicinal , Trypsin Inhibitors/genetics , Fabaceae/chemistry , Gene Expression , Gene Expression Regulation, Plant , Genes, Reporter , Multigene Family , Plant Stems/chemistry , Seeds/genetics , Trypsin Inhibitors/analysis , Trypsin Inhibitors/physiology
8.
Plant Physiol ; 88(3): 525-7, 1988 Nov.
Article in English | MEDLINE | ID: mdl-16666340

ABSTRACT

Abscisic acid (ABA) in the stem of akamatsu (Pinus densiflora) was identified and quantified by gas chromatography-mass spectrometry-selected ion monitoring using hexadeuterated ABA as an internal standard. tert-Butyldimethylsilyl ester was used as a derivative of ABA. This derivative had high sensitivity and selectivity for ABA determination. ABA concentrations in cambial region scrapings were independent of the cessation of cambial activity.

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