The senescence syndrome in plants: an overview of phytogerontology

1994 ◽  
Vol 102 ◽  
pp. 447-458 ◽  
Author(s):  
J. R. Hillman ◽  
S. M. Glidewell ◽  
N. Deighton
Keyword(s):  
Cell Differentiation ◽  
Intact Plant ◽  
Layer Formation ◽  
Physical Damage ◽  
Abscission Layer ◽  
Pests And Diseases ◽  
Environmental Perturbations ◽  
Plant Sciences

SynopsisThe deteriorative processes leading to the death of a population, individual or part of an individual can be genetically programmed or induced by environmental perturbations, physical damage, pests and diseases. Senescence in multicellular plants is typically a phenomenon resulting from cell differentiation and loss of totipotency. Recycling of nutrients released from senescent cells, abscission layer formation, containment of pathogens and dispersal of progeny are crucial aspects of senescence management. Senescence-related autocatalytic changes induced by substances generally thought to regulate senescence may not mirror the sequence of changes occurring naturally through correlative processes in the intact plant. The chloroplast has a key role in reversing senescence-related degradation of other organelles. Conventional symptoms of senescence used in plant sciences have obscured common theories of senescence regulation for all types of organism.

scholarly journals PENGARUH 6-BENZILAMINOPURIN (BAP) TERHADAP PEMBENTUKAN LAPISAN PEMISAH (ZONA ABSISI) PADA TANGKAI KUNTUM BUNGA KACANG HIJAU, VIGNA RADIATA (L.) Wilczek VARITAS WALET

2015 ◽  
Vol 3 (1) ◽  
pp. 13
Author(s):  
Mrs Kusdianti ◽  
Trimurti H. Wardini
Keyword(s):  
Cell Division ◽  
Vigna Radiata ◽  
Control Plant ◽  
Abscission Zone ◽  
Layer Formation ◽  
Abscission Layer ◽  
Histological Changes ◽  
Result Show ◽  
Treated Plant

The effect of 6-benzylaminopurine (BAP) on separation layer formation of mungbean Vigna radiata (L.) Wilczek var. walet was carried out. The objective was to know the effect of BAP on separation layer formation. The experiment was done by spraying the first inflorescent with 8 x 10-4 M BAP three days before and three days after the fifth flower was anthesis. Samples of flower pedicellus were taken three days before dan three days after fifth flower was bloom. Then they were fixed and processed for anatomical observation by preparing histological slides accoding to O’Brien and Horner (1981). The result show that in control plant, two days before the fifth flower started to anthesis, cells of the abscission zone started to be activated to form separation layer. It was initiated by cell division within the adaxial edge and progressing inward across the cortex to the vascular strands. Abscission layer was completed at the time or a day after the fifth flower was anthesis. No histological changes observed in with 8 x 10-4 M BAP treated plant. No abscission layer were recorded for the pedicels treated plant during the course of the experimentKey word : 6-benzylaminopurine (BAP), abscission zone, pedicel

scholarly journals Effect of quantitative trait loci for seed shattering on abscission layer formation in Asian wild rice Oryza rufipogon

2014 ◽  
Vol 64 (3) ◽  
pp. 199-205 ◽  
Author(s):  
Than Myint Htun ◽  
Chizuru Inoue ◽  
Orn Chhourn ◽  
Takashige Ishii ◽  
Ryo Ishikawa
Keyword(s):  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Wild Rice ◽  
Oryza Rufipogon ◽  
Layer Formation ◽  
Abscission Layer ◽  
Seed Shattering ◽  
Trait Loci

scholarly journals Inhibition of abscission layer formation by an interaction of two seed-shattering loci, sh4 and qSH3, in rice

2015 ◽  
Vol 90 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Chizuru Inoue ◽  
Than Myint Htun ◽  
Kanako Inoue ◽  
Ken-ichi Ikeda ◽  
Takashige Ishii ◽  
...  
Keyword(s):  
Layer Formation ◽  
Abscission Layer ◽  
Seed Shattering

scholarly journals Pests and diseases in a changing climate a major challenge for Finnish crop production

2008 ◽  
Vol 20 (1) ◽  
pp. 3 ◽  
Author(s):  
K. HAKALA ◽  
A.O. HANNUKKALA ◽  
E. HUUSELA-VEISTOLA
Keyword(s):  
Crop Production ◽  
Growing Season ◽  
Triticum Aestivum L ◽  
Climatic Conditions ◽  
Production Potential ◽  
Physical Damage ◽  
Hordeum Vulgare L ◽  
Brassica Napus L ◽  
Crop Species ◽  
Pests And Diseases

A longer growing season and higher accumulated effective temperature sum (ETS) will improve crop production potential in Finland. The production potential of new or at present underutilised crops (e.g. maize (Zea mays L.), oilseed rape (Brassica napus L.), lucerne (Medicago sativa L.)) will improve and it will be possible to grow more productive varieties of the currently grown crops (spring wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), oats (Avena sativa L.)). Also cultivation of autumn sown crops could increase if winters become milder and shorter, promoting overwintering success. Climatic conditions may on the other hand become restrictive in many ways. For example, early season droughts could intensify because of higher temperatures and consequent higher evaporation rates. Current low winter temperatures and short growing season help restrict the development and spread of pests and pathogens, but this could change in the future. Longer growing seasons, warmer autumns and milder winters may initiate new problems with higher occurrences of weeds, pests and pathogens, including new types of viruses and virus vectors. Anoxia of overwintering crops caused by ice encasement, and physical damage caused by freezing and melting of water over the fields may also increase. In this study we identify the most likely changes in crop species and varieties in Finland and the pest and pathogen species that are most likely to create production problems as a result of climate change during this century.;

scholarly journals Composition and carbon dynamics of forests in northeastern North America in a future, warmer worldThis article is one of a selection of papers from NE Forests 2100: A Synthesis of Climate Change Impacts on Forests of the Northeastern US and Eastern Canada.

2009 ◽  
Vol 39 (2) ◽  
pp. 213-230 ◽  
Author(s):  
Jacqueline E. Mohan ◽  
Roger M. Cox ◽  
Louis R. Iverson
Keyword(s):  
United States ◽  
Climate Change Impacts ◽  
Forest Composition ◽  
Suitable Habitat ◽  
Northeastern United States ◽  
Physical Damage ◽  
Climatic Effects ◽  
Eastern Canada ◽  
Actual Distribution ◽  
Pests And Diseases

Increasing temperatures, precipitation extremes, and other anthropogenic influences (pollutant deposition, increasing carbon dioxide) will influence future forest composition and productivity in the northeastern United States and eastern Canada. This synthesis of empirical and modeling studies includes tree DNA evidence suggesting tree migrations since the last glaciation were much slower, at least under postglacial conditions, than is needed to keep up with current and future climate warming. Exceedances of US and Canadian ozone air quality standards are apparent and offset CO2-induced gains in biomass and predispose trees to other stresses. The deposition of nitrogen and sulfate in the northeastern United States changes forest nutrient availability and retention, reduces reproductive success and frost hardiness, causes physical damage to leaf surfaces, and alters performance of forest pests and diseases. These interacting stresses may increase future tree declines and ecosystem disturbances during transition to a warmer climate. Recent modeling work predicts warmer climates will increase suitable habitat (not necessarily actual distribution) for most tree species in the northeastern United States. Species whose habitat is declining in the northeastern United States currently occur in Canadian forests and may expand northward with warming. Paleoecological studies suggest local factors may interact with, even overwhelm, climatic effects, causing lags and thresholds leading to sudden large shifts in vegetation.

A technique for protecting delicate specimens during processing

1989 ◽  
Vol 47 ◽  
pp. 982-983
Author(s):  
R.J. Mount ◽  
R.V. Harrison
Keyword(s):  
Basilar Membrane ◽  
Low Cost ◽  
Organ Of Corti ◽  
Region Of Interest ◽  
Sensory Epithelium ◽  
Physical Damage ◽  
Air Drying ◽  
Specimen Handling ◽  
Two Component

The sensory end organ of the ear, the organ of Corti, rests on a thin basilar membrane which lies between the bone of the central modiolus and the bony wall of the cochlea. In vivo, the organ of Corti is protected by the bony wall which totally surrounds it. In order to examine the sensory epithelium by scanning electron microscopy it is necessary to dissect away the protective bone and expose the region of interest (Fig. 1). This leaves the fragile organ of Corti susceptible to physical damage during subsequent handling. In our laboratory cochlear specimens, after dissection, are routinely prepared by the O-T- O-T-O technique, critical point dried and then lightly sputter coated with gold. This processing involves considerable specimen handling including several hours on a rotator during which the organ of Corti is at risk of being physically damaged. The following procedure uses low cost, readily available materials to hold the specimen during processing ,preventing physical damage while allowing an unhindered exchange of fluids.Following fixation, the cochlea is dehydrated to 70% ethanol then dissected under ethanol to prevent air drying. The holder is prepared by punching a hole in the flexible snap cap of a Wheaton vial with a paper hole punch. A small amount of two component epoxy putty is well mixed then pushed through the hole in the cap. The putty on the inner cap is formed into a “cup” to hold the specimen (Fig. 2), the putty on the outside is smoothed into a “button” to give good attachment even when the cap is flexed during handling (Fig. 3). The cap is submerged in the 70% ethanol, the bone at the base of the cochlea is seated into the cup and the sides of the cup squeezed with forceps to grip it (Fig.4). Several types of epoxy putty have been tried, most are either soluble in ethanol to some degree or do not set in ethanol. The only putty we find successful is “DUROtm MASTERMENDtm Epoxy Extra Strength Ribbon” (Loctite Corp., Cleveland, Ohio), this is a blue and yellow ribbon which is kneaded to form a green putty, it is available at many hardware stores.

Electron microscope study of the secretory activity of epithelial cells in embryonic thymus

1990 ◽  
Vol 48 (3) ◽  
pp. 382-383
Author(s):  
H. Alasam
Keyword(s):  
Cell Differentiation ◽  
T Cell ◽  
Epithelial Cells ◽  
Electron Density ◽  
Secretory Activity ◽  
T Cell Differentiation ◽  
High Electron ◽  
Transmission Electron ◽  
Medullary Epithelial Cells ◽  
Thymic Factor

The possibility that intrathymic T-cell differentiation involves stem cell-lymphoid interactions in embryos led us to study the ultrastructure of epithelial cell in normal embryonic thymus. Studies in adult thymus showed that it produces several peptides that induce T-cell differentiation. Several of them have been chemically characterized, such as thymosin α 1, thymopoietin, thymic humoral factor or the serum thymic factor. It was suggested that most of these factors are secreted by populations of A and B-epithelial cells.Embryonic materials were obtained from inbred matings of Swiss Albino mice. Thymuses were disected from embryos 17 days old and prepared for transmission electron microscopy. Our studies showed that embryonic thymus at this stage contains undifferentiated and differentiated epithelial cells, large lymphoblasts, medium and few small lymphocytes (Fig. 5). No differences were found between cortical and medullary epithelial cells, in contrast to the findings of Van Vliet et al,. Epithelial cells were mostly of the A-type with low electron density in both cytoplasm and nucleus. However few B-type with high electron density were also found (Fig. 7).

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