Structural Features of Plant Morphogenesis in Vitro. During this time, he was mainly focusing on the cell biology of plant cytoskeleton, especially as related to growth and polarity of cells in root apex. His current main research interest is the signal-mediated interactions between membrane trafficking and cytoskeleton in two plant model species Zea mays and Arabidopsis thaliana.
He co-edited three books: Structure and Function of Roots , Actin: Diedrik Menzel graduated at the Free University of Berlin in His work is related to Cell architecture and morphogenesis in higher plants and algae. Long standing interest in on the molecular analysis and intracellular visualization of cytoskeletal-, motor-, and regulatory proteins.
Current emphasis is on actin Cytoskeleton and endomembrane dynamics, molecular architecture of plant myosins. His other interest is on Gene expression and intracellular transport of mRNA in the unicellular green alga Acetabularia. About Help Blog Jobs Welcome to our new website. Benton Richard Fortey View All. Go to British Wildlife.
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Cell Division Control in Plants. The Plant Endoplasmic Reticulum. Cell Biology of Plant Nematode Parasitism. Functional Organization of the Plant Nucleus. Lipid Signaling in Plants. Cambial reactivation that induced by localized heating was stopped just after cambial reactivation to observe the effects of rapid decrease in temperature on cambial cells.
In addition, presence of nucleus in heated-reactivated cambial cells and non-heated cambial cells were examined to clarify the status of cambial cells whether the cells were alive or not. The possible mechanism of cambial activity in relation with decrease in temperature will be discussed. The Cryptomeria japonica trees were examined from 8 January to 28 February and Abies firma seedlings were examined from 13 January to 3 March In case of adult Cryptomeria japonica trees, electric heating tape Silicone-Rubber Heater; O and M Heater, Nagoya, Japan , 50 cm in length and 30 cm in width, was wrapped at one side of the main stem of each tree at breast height Fig.
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In case of Abies firma seedlings, electric heating ribbon Nippon Heater Co. Tokyo, Japan , 6 m in length and 0. No abnormal structures were found by naked eyes in the stems after artificial heating. In adult Cryptomeria japonica trees and Abies firma seedlings, localized heat treatment was started from 8 January and 13 January , respectively. Continuous heating was applied until cambial reactivation and heating system was stopped on 18 January and 19 January in both species, respectively.
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After stop of heating, samples were collected from heated and non-heated control portions of the stem until 27 February and 3 March , in both cases, respectively. In case of adult Cryptomeria japonica trees, samples were taken at three to four days intervals from heated stems and non-heated stems under natural conditions throughout the sampling period.
A series of small blocks 2x2x1 cm 3 which contained phloem, cambium and some xylem cells, was removed with a disposable scalpel and chisel with a zigzag fashion to eliminate any effects of wounding from heated stems and stems under natural conditions. Each block was cut into 2 mm thick samples immediately after removal from the tree. In case of Abies firma , four sample seedlings two from heated stem and two from non-heated control stem were cut in every sampling date at one day interval until 19 January Then sampling was done at one week interval until 3 March For non-heated control sample, we used seedling that was not heated and sample was taken from the same portion of stem at cm above the stem base.
In each sampling date, we tried to collect the seedlings that had almost the same stem height and diameter to avoid any differences among seedlings.
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The heated and non-heated control portion of stems was cut into 2 mm thick samples immediately after removal from the tree. Preparation of samples for light microscopy: Fixed samples were washed in 0.
After washing in phosphate buffer, specimens were dehydrated in a graded ethanol series and embedded in epoxy resin. Air temperatures during experiments: Daily maximum, average and minimum air temperatures during each experimental period were obtained from the Japan Meteorological Agency that located in Fuchu, Tokyo.
Maximum, average and minimum air temperatures from 1 January to 31 March during the first experiment for Cryptomeria japonica and from 1 January to 31 March during the second experiment for Abies firma are shown in Fig. After stop of heating, in February , the minimum temperature was In February , the minimum temperature was No division of fusiform cambial cells and ray cambial cells was detected in samples of cambium of Cryptomeria japonica and Abies firma that had been collected on 8 January and 13 January , respectively Fig.
During dormancy, the cambium consisted of five or six radial layers of radially narrow and compactly arranged cells Fig. Timing of cambial reactivation and xylem differentiation in heated stems: In heated Cryptomeria japonica and Abies firma stems, cambial reactivation occurred after 6 days and 2 days of heating, on 14 January and 15 January , respectively Fig.
After production of radial files of fusiform cambium on 18 January in Cryptomeria japonica and on 19 January in Abies firma , heating system was stopped in both species Fig. Effects of rapid decrease in temperature on cambial cells after stop of heating: One week later of stop of heating, on 25 January and 26 January , the cambial cells became shrunk and cell contents coagulated in phloem and cambial cells in adult Cryptomeria japonica trees and Abies firma seedlings Fig. The higher magnified image of the same portion of Fig. At that time the structure, shape and size of cambial cells were not at normal condition Fig.
Two weeks later of stop of heating, on 1 February and 2 February , the cambial cells were almost at the same condition as well as shrunk cambium observed in both species Fig. In addition, no new cell plates were observed in the cambial zone of Cryptomeria japonica and Abies firma stems indicating that cambial activity was reduced or almost stopped Fig. Two weeks later of stop of heating, on 1 February and 2 February , in the same sample of Cryptomeria japonica and Abies firma , nucleus was present in ray cambial cells Fig. After one month of stop of heating, on 18 February , the shrunk cambium produced new tracheids with deformed structure of secondary xylem as compared with the normal xylem differentiation in Cryptomeria japonica trees Fig.
Relationship between shrinkage of cambium and temperature data: Due to the stop of heating, temperature decreased rapidly in the heated portions of the stems in both species Fig. When we stopped the heating system in February, the minimum atmospheric temperature was ranged from The temperature profile and microscopic images of cambial cells clearly showed that shrunk cambium with coagulated cell contents produced due to rapid decrease in temperature in adult Cryptomeria japonica trees and Abies firma seedlings in February Fig.
Rapid decrease in temperature on localized-heated stems induced coagulation of cell contents in cambial cells with deformed shape and size of phloem cells in Cryptomeria japonica trees and Abies firma during winter dormancy in February. One week later of stop of heating, shrunk with abnormal structure of longitudinal phloem parenchyma cells were observed in localized-heat-induced differentiating phloem cells.
In our previous research, we observed that due to the rapid decrease in temperature, cell wall thickening of phloem fibers started earlier than xylem cells in Cryptomeria japonica trees and Abies firma stems. In addition, division of phloem cells started prior to cambial reactivation and xylem differentiation in heated stems and under natural conditions at warmer early spring of hybrid poplar Populus sieboldii x Populus grandidentata , indicating that phloem cells were able to make quick response to increase in temperature than cambial cells and xylem cells Begum et al.
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In present study, it was found that coagulation of cell contents occurred in longitudinal phloem parenchyma cells due to stop of heating. This observation suggests that phloem cells might respond to decrease in temperature more rapidly than xylem cells in conifers. It was already proved that temperature was a limiting factor in the onset of cambial reactivation and xylem differentiation during the quiescent dormant state in conifers Savidge and Wareing, ; Barnett and Miller, ; Oribe and Kubo, ; Oribe et al.
Increase in temperature or warmer early spring induced earlier cambial reactivation and xylem differentiation in trees Oribe and Kubo, ; Oribe et al. Similarly, in the present study, earlier cambial reactivation and xylem differentiation was induced by localized heating in Cryptomeria japonica trees and Abies firma stems during winter dormancy in February indicating that temperature is one of the most important trigger for start of cambial reactivation.
Under these conditions, no formation of new cell plates occurred in the cambium in March in Cryptomeria japonica trees Begum et al. Thus, low temperatures appear to be very important for maintenance of a quiescent state Begum et al.
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In our present study, it was observed that rapid decrease in temperature in heated reactivated cambium induced shrinkage of cambial cells with coagulation of cell contents. In addition, nucleus was observed in those shrunk cambial cells indicating that cambial cells were alive. Therefore, it appears that rapid changes in environmental conditions might induce cellular changes in cambial cells. Certain abnormal environmental conditions can induce the formation of various structures, For example, wider tracheids were produce under water stress condition in plants Landrum, ; Gutierrez et al.
Salinity stress decreased xylem exudation rate and collapsed xylem cells Kabir et al. Drought stress increased vessel wall thickness Mostajeran and Rahimi-Eichi, and showed highest cell wall associated peroxidase activity in leaf cells Hamad et al. Low temperature induced greater degree of shrinkage in cell structure Singh and Pandey, Chilling strees decreased stomatal conductance and increased peroxidase enzymatic activity in plant cells Islam et al.
In general, with increasing methyl jasmonate concentration, chilling injury reduced significantly Zolfagharinasab and Hadian, Deflowering of rachis induced narrower xylem cells which inhibit water conduction to the top of the rachis resulted few or smaller sized pod production Begum et al. Thus, environmental stress plays a significant role on morphology and structure of cells in plant.
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It was also reported that continuation of cambial activity and xylem differentiation required a constant threshold maximum temperature Begum et al. The results suggest that cambial activity was stopped due to rapid changes of temperature in February. The present results showed that localized heating during cambial dormancy induced earlier cambial reactivation in conifers and subsequent rapid decrease in temperature just after cambial reactivation induced formation of shrinkage cambium.
The results suggest that low temperature might changes endogenous balances that induced shrinkage of cambium with deformed structure of differentiating tracheids which would be helpful to study the mechanism of cambial activity in conifers. In addition, in the present research we observed that without any obvious changes of day length, supply of photosynthates and auxin, only rapid decrease in temperature might have a direct effect on reduction or stopping of cambial activity in Cryptomeria japonica and Abies firma trees.
It can be concluded that rapid decrease in temperature might be expected to have a direct effect on continuous cambial cell division in Cryptomeria japonica and Abies firma stems. The results indicate that cambium and its derivatives can response directly to changes in temperature. Finally, it can be concluded that rapid decrease in temperature might be one of the most important factor that regulate continuous normal cambial cell division in conifers indicating that earlier cambial reactivation might have risk of frost damage because cold tolerance decreases after cambial reactivation.
The effect of applied heat on graft union formation in dormant Picea sitchensis Bong. Cold stability of microtubules in wood-forming tissues of conifers during seasons of active and dormant cambium.
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Anatomy of the rachis of the inflorescence of pigeonpea Cajanus cajan. Temperature responses of cambial reactivation and xylem differentiation in hybrid poplar Populus sieboldii x P. Cambial sensitivity to rising temperatures by natural condition and artificial heating from late winter to early spring in the evergreen conifer Cryptomeria japonica. Changes in the localization and levels of starch and lipids in cambium and phloem during cambial reactivation by artificial heating of main stems of Cryptomeria japonica trees.