Ageing increases the sensitivity of neem (Azadirachta indica) seeds to imbibitional stress

2004 ◽  
Vol 14 (2) ◽  
pp. 205-217 ◽  
Author(s):  
Oblé Neya ◽  
Elena A. Golovina ◽  
Jaap Nijsse ◽  
Folkert A. Hoekstra
Keyword(s):  
Azadirachta Indica ◽  
Barrier Properties ◽  
Seed Moisture Content ◽  
Peripheral Cell ◽  
Seed Desiccation ◽  
Embryo Cells ◽  
Cell Layers ◽  
Imbibitional Damage ◽  
High Quality Seed ◽  
Aged Seeds

Imbibitional stress was imposed on neem (Azadirachta indica) seeds by letting them soak for 1 h in water at unfavourable, low temperatures before further incubation at 30°C. Sensitivity to low imbibition temperatures increased with a decrease in seed moisture content (MC). To investigate a possible involvement of seed age in the extent of imbibitional damage, initially high-quality seed lots that differed in storage history (10 weeks versus 10 months) were examined at 4 and 7% MC (fresh weight basis). After 10 months of storage, the 7% MC seeds had become sensitive to imbibitional stress. Further drying (1 week) to 4% MC affected aged seeds more than non-aged seeds. Barrier properties of cellular membranes in axes excised after 1 d of rehydration were estimated using a spin-probe technique. The proportion of cells with intact membranes increased with increasing imbibition temperature. For each temperature tested, there were more cells with leaky membranes after 10 months than after 10 weeks of dry storage. Localization of embryo cells displaying loss of turgor and abnormal cellular structure was accomplished using cryo-planing, followed by cryo-scanning electron microscopy. Inspection of the cryo-planed surfaces confirmed that imbibitional damage was temperature dependent, occurring at the periphery. Ageing increased the number of imbibitionally damaged, peripheral cell layers. Germination was estimated to fail when less than 70% of axis cells were alive. We conclude that ageing increases the sensitivity to imbibitional stress. Both the fast ageing and the sensitivity to imbibitional stress might explain the apparent controversies about neem seed desiccation tolerance and storage behaviour.

The Role of the Peripheral Cell Layers in the Geotropic Curvature of Sunflower Hypocotyls: a New Model of Shoot Geotropism

1977 ◽  
Vol 4 (3) ◽  
pp. 337 ◽  
Author(s):  
R Firn ◽  
J Digby
Keyword(s):  
Helianthus Annuus ◽  
Growth Regulator ◽  
Differential Rate ◽  
Lateral Movement ◽  
Differential Growth ◽  
Peripheral Cell ◽  
New Model ◽  
Helianthus Annuus L ◽  
Cell Layers

The rate of elongation of sunflower (Helianthus annuus L.) hypocotyl sections was found to be dependent on the rate of growth of the outermost cell layers (peripheral cell layers) of that tissue. Hypocotyl sections from which those layers had teen peeled grew but did not show typical geotropic curvature. A model of geotropic curvature is proposed where the differential growth causing curvature is due to a differential rate of elongation between the upper and lower peripheral cell layers of a horizontal shoot. In the model it is speculated that the peripheral cell layers are the site of both geoperception and georesponse. The model does not involve a lateral movement of a growth regulator and experiments with longitudinally bisected hypocotyl sections provided evidence consistent with this model but inconsistent with the Cholodny-Went theory of geotropism.

scholarly journals Storage of seeds of Calamus palustris var. cochinchinensis

2020 ◽  
Vol 48 (2) ◽  
pp. 201-207
Author(s):  
Y.K. Fan ◽  
M. Liu ◽  
J.X. Hu ◽  
M.Y. Ji ◽  
Q.Y. Lan
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Storage Temperature ◽  
Aluminum Foil ◽  
Effect Of Temperature ◽  
Seed Moisture Content ◽  
Seed Desiccation ◽  
Seed Moisture ◽  
Mature Seeds

The present study examined the effect of temperature (15, 20, 25, 30 and 20/30°C) on germination and the storage behaviour of freshly harvested mature seeds of Calamus palustris var. cochinchinensis. Seed desiccation tolerance and the effects of storage temperature (4 and 15°C), perlite water content (120, 180 and 240%) and seed moisture content (27.8, 38.2 and 49.2%) on viability were observed. Seeds had a higher germination at 25°C (88.3%) than at the other tested temperatures. Germination decreased as the seed moisture content decreased during desiccation. The germination of seeds stored at 15°C was higher than that of seeds stored at 4°C. Germination of seeds stored at 15 and 4°C was <65% and with extension of storage time, the germination decreased, indicating that neither temperature can be used for long-term conservation. For short-term storage, the seeds can be stored at 15°C with perlite with 180% water content in plastic bottles or at 15°C with 49.2% moisture content sealed inside aluminum foil bags.

Seed storage behaviour of 101 woody species from the tropical rainforest of southern China: a test of the seed-coat ratio–seed mass (SCR–SM) model for determination of desiccation sensitivity

2014 ◽  
Vol 62 (4) ◽  
pp. 305 ◽  
Author(s):  
Qin-ying Lan ◽  
Ke Xia ◽  
Xiao-feng Wang ◽  
Jun-wei Liu ◽  
Jin Zhao ◽  
...  
Keyword(s):  
Moisture Content ◽  
Seed Coat ◽  
Tropical Rainforest ◽  
Southern China ◽  
Seed Mass ◽  
Seed Storage ◽  
Woody Species ◽  
Seed Moisture Content ◽  
Seed Desiccation ◽  
Desiccation Sensitivity

The Xishuangbanna tropical rainforest in Yunnan Province is the greatest biodiversity hotspot in China. However, the biodiversity of this region is under threat, making seed conservation through seed and/or germplasm banking particularly urgent and crucial. Seed desiccation sensitivity limits the possibility of seed banking of 47% of tropical rainforest species. Thus, knowing if a species has desiccation-sensitive seeds is an important first step in seed banking; however, often resources are limited, making it difficult to determine storage behaviour for all the species in a region. Prediction of seed sensitivity using the SCR–SM model based on seed-coat ratio (SCR) and seed dry mass (SM) might be an alternative for determining desiccation sensitivity of seeds of each species. Here, seed-desiccation sensitivity of 101 woody species from the Xishuangbanna tropical forest were analysed using this model, and physiological determinations were made for a total of 25 species. Seed storage behaviour for 59 species was used for model validation, and storage behaviour of 88% of these species was successfully predicted. Seed storage behaviour of 83% of the 59 species was successfully predicted using the 1000-seed weigth–moisture content (TSW–MC) criteria, which include seeds with 1000-seed weight >500 g and seed moisture content at shedding of 30 –70%. The two predictive methods were subsequently used to predict seed desiccation sensitivity for another 42 species from Xishuangbanna whose storage behaviour was uncertain. Our results indicated that ~50% of the species in Xishuangbanna are likely to have desiccation-sensitive seeds.

scholarly journals Epac1 Is Crucial for Maintenance of Endothelial Barrier Function through A Mechanism Partly Independent of Rac1

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2170
Author(s):  
Alexander García-Ponce ◽  
Katharina Schuster ◽  
Stein-Ove Døskeland ◽  
Rolf K. Reed ◽  
Fitz-Roy E. Curry ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Side Effects ◽  
Barrier Function ◽  
Barrier Properties ◽  
Endothelial Barrier ◽  
Wild Type ◽  
Endothelial Barrier Function ◽  
Rac1 Activity ◽  
Cell Layers ◽  
Camp Levels

Epac1 (exchange protein activated by cAMP) stabilizes the endothelial barrier, but detailed studies are limited by the side effects of pharmacological Epac1 modulators and transient transfections. Here, we compare the key properties of barriers between endothelial cells derived from wild-type (WT) and Epac1-knockout (KO) mice myocardium. We found that KO cell layers, unlike WT layers, had low and cAMP-insensitive trans-endothelial resistance (TER). They also had fragmented VE-cadherin staining despite having augmented cAMP levels and increased protein expression of Rap1, Rac1, RhoA, and VE-cadherin. The simultaneous direct activation of Rac1 and RhoA by CN04 compensated Epac1 loss, since TER was increased. In KO-cells, inhibition of Rac1 activity had no additional effect on TER, suggesting that other mechanisms compensate the inhibition of the Rac1 function to preserve barrier properties. In summary, Epac1 is crucial for baseline and cAMP-mediated barrier stabilization through mechanisms that are at least partially independent of Rac1.

Seed germination in Prunus cerasoides D. Don influenced by natural seed desiccation and varying temperature in Central Himalayan region of Uttarakhand, India.

2016 ◽  
Vol 5 (05) ◽  
pp. 4567 ◽  
Author(s):  
Bhawna Tewari* ◽  
Ashish Tewari
Keyword(s):  
Moisture Content ◽  
Natural Habitat ◽  
Colour Change ◽  
Himalayan Region ◽  
Seed Moisture Content ◽  
Hard Seed ◽  
Seed Desiccation ◽  
Seed Maturity ◽  
Seed Moisture ◽  
Prunus Cerasoides

Prunus cerasoides D. Don the Himalayan wild cherry is one lesser known multipurpose tree species of Himalaya. The tree prefers to grow on sloping grounds between the altitudes of 1200-2400 m, on all types of soils and rocks. The tree is used as a medicinal plant in Himalayan region. The fruit is edible and the pulp is used to make a cherry brandy. The species has poor germination and seedling establishment in natural habitat. The over exploitation of seeds of the species coupled with relatively hard seed coat has adversely affects the germination of seeds in their natural habitat. The information about the seed maturity and technique of germination enhancement is scanty. The present study was conducted to assess the exact maturity time and optimum temperature for enhancement of germination in seed of P. cerasoides.  The fruit/seeds were collected from six sites covering the altitudinal range of 1350 – 1810 m during the period (2003-2004). The colour change of fruit from dark green to red was a useful indicator of seed maturity. Maximum germination coincided with 50.24 ± 0.19 % fruit and 30.11 ± 0.57 % seed moisture content. Negative correlation existed between germination and seed moisture content (r = 0.294; P< 0.01). Significantly higher germination occurred when seeds were placed above the paper at 25º C.

Morphophysiological epicotyl dormancy in seeds of threePsychotriaspecies from Sri Lanka: first record for Rubiaceae

2016 ◽  
Vol 26 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Yasoja S. Athugala ◽  
K.M.G. Jayasuriya ◽  
A.M.T.A. Gunaratne ◽  
Carol C. Baskin
Keyword(s):  
Rainy Season ◽  
First Record ◽  
Physical Dormancy ◽  
Seed Moisture Content ◽  
Seed Desiccation ◽  
Morphophysiological Dormancy ◽  
Seed Moisture ◽  
Before And After ◽  
Radicle Emergence ◽  
Shoot Emergence

AbstractTo increase our knowledge of the diversity of seed dormancy and germination in Rubiaceae, we investigated seed desiccation sensitivity and germination of threePsychotriaspecies. Seeds ofP. gardneri, P. nigraandP. zeylanicagerminated to high percentages at <15% seed moisture content. Intact seeds ofP. zeylanicaandP. nigraimbibed water and thus do not have physical dormancy. More than 50% of the seeds ofP. zeylanica, P. nigraandP. gardneritook 33, 53 and 110 d, respectively, at 25°C for the radicle to emerge, and embryo growth occurred before and after radicle emergence. Thus, seeds have morphophysiological dormancy. Shoot emergence ofP. nigraandP. zeylanicaseeds was delayed 50 and 80 d after radical emergence, respectively; thus, seeds have epicotyl morphophysiological dormancy (eMPD). This is the first report of eMPD in Rubiaceae. Since warm stratification promoted both radicle and shoot emergence in seeds ofP. zeylanicaandP. nigra, the level of eMPD is non-deep simple. Hence, dormancy of the studiedPsychotriaspp. can be described as C1bBb(radicle)–C1bBb(epicotyl), i.e. the embryo is underdeveloped and grows prior to radicle emergence and epicotyl emergence under warm temperatures (Bb), and both the radicle and epicotyl have non-deep simple physiological dormancy broken by warm temperatures (C1b). In twoPsychotriaspecies studied in detail, radicle emergence occurs at the beginning of the rainy season and plumule emergence at the peak rainy season when conditions are most favourable for rapid seedling development.

scholarly journals Migration of Oil Bodies in Embryo Cells during Acquisition of Desiccation Tolerance in Chemically Defoliated Corn (Zea mays L.) Seed Production Fields

Agriculture ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Ashley N. Dean ◽  
Katharina Wigg ◽  
Everton V. Zambiazzi ◽  
Erik J. Christian ◽  
Susana A. Goggi ◽  
...  
Keyword(s):  
Seed Germination ◽  
Seed Production ◽  
Frost Damage ◽  
Oil Bodies ◽  
Seed Moisture Content ◽  
Migration Patterns ◽  
Seed Corn ◽  
Production Practice ◽  
Seed Harvest ◽  
Embryo Cells

Chemical defoliation of seed corn production fields accelerates seed maturation and desiccation and expedites seed harvest. Early seed harvest is important to minimize the risk of frost damage while in the field. This newly adopted seed production practice also allows seed companies to plan harvest and manage dryer space more efficiently. However, premature defoliation may interfere with the migration of oil bodies within embryo cells during desiccation and affect seed germination and vigor. The objective of this study was to investigate the effect of chemical defoliation on the migration patterns of oil bodies within embryo cells during desiccation. Chemically defoliated and non-defoliated plants from five commercial hybrid seed corn fields were sampled in 2014 and 2015. Whole ears with husks were harvested before and after defoliant application at 600 g H2O kg−1 fresh weight (fw), and weekly thereafter until seed reached approximately 300–350 g H2O kg−1 fw. Ten embryos extracted from center-row seeds were fixed to stop metabolic processes, then sliced, processed, and photographed using scanning transmission electron microscopy. The oil bodies within embryo cells followed normal migration patterns according to seed moisture content, regardless of defoliation treatment. Seed germination and vigor were verified and were not significantly affected by defoliation. Chemical defoliation is a viable production practice to accelerate seed corn desiccation and to manage harvest and seed dryer availability more efficiently without negatively affecting seed germination and vigor.

Response of red spruce seedlings to aluminum toxicity in nutrient solution: alterations in root anatomy

1990 ◽  
Vol 20 (7) ◽  
pp. 1001-1011 ◽  
Author(s):  
Carolyn J. McQuattie ◽  
George A. Schier
Keyword(s):  
Nutrient Solution ◽  
Aluminum Toxicity ◽  
Electron Microscopic Examination ◽  
Red Spruce ◽  
Root Anatomy ◽  
Root Tips ◽  
Electron Microscopic ◽  
Material Loss ◽  
Peripheral Cell ◽  
Cell Layers

One year old red spruce (Picearubens Sarg.) were grown for 37 days in a nutrient solution containing 0, 50, 100, or 200 mg/L Al. No macroscopic evidence of Al injury was observed in the shoots of seedlings; however, Al toxicity symptoms were well developed in the roots. Aluminum reduced root length but increased root diameter and the number of cell layers in the root cap. Light and electron microscopic examination of root tips and segments 5–10 mm from the tip revealed numerous cellular changes in Al-stressed roots: premature vacuolation, accumulation of phenoliclike material, loss of cells from peripheral cell layers, formation of intercellular spaces, increased disruption of cellular membranes, and degeneration of the cytoplasm.

Relationship between seed desiccation sensitivity, seed water content at maturity and climatic characteristics of native environments of nineCoffeaL. species

2000 ◽  
Vol 10 (3) ◽  
pp. 293-300 ◽  
Author(s):  
Stéphane Dussert ◽  
Nathalie Chabrillange ◽  
Florent Engelmann ◽  
François Anthony ◽  
Jacques Louarn ◽  
...  
Keyword(s):  
Water Content ◽  
Seed Development ◽  
Dry Season ◽  
Natural Habitats ◽  
Seed Moisture Content ◽  
Seed Desiccation ◽  
Desiccation Sensitivity ◽  
Climatic Characteristics ◽  
Coffee Species ◽  
Seed Water Content

AbstractA broad variability for seed desiccation sensitivity, as quantified by the water content and the water activity at which half of the initial viability is lost, has been previously observed within nine African coffee species. In order to investigate if these different degrees of desiccation sensitivity correspond to an adaptive trait, additional data, such as the duration of seed development and seed water content at maturity, were measured for these species, and the relationships between these parameters and some climatic characteristics of their specific native environments were investigated. Since flowering in all coffee species occurs only a few days after the main rainfall marking the end of the dry season, simulations could be made, based on the continuous sequences of rainfall data compiled in databases of nine climatic stations, chosen for their appropriate location in the collecting areas. The simulations revealed a highly significant correlation between the duration of seed development and that of the wet season. Consequently, mature seeds are shed at the beginning of the following dry season. Moreover, the mean number of dry months that seeds have to withstand after shedding was significantly correlated with the parameters used to quantify seed desiccation sensitivity. By contrast, seed moisture content at maturity was not correlated with the level of seed desiccation tolerance. All these results are discussed on the basis of more detailed descriptions of the natural habitats of the coffee species studied.

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