scholarly journals Seed-coat thickness explains contrasting germination responses to smoke and heat by Leucadendron species

2021 ◽  
Author(s):  
Byron B. Lamont ◽  
Pablo Gomez Barreiro ◽  
Rosemary Newton
Keyword(s):  
Water Uptake ◽  
Seed Coat ◽  
Water Permeability ◽  
Seed Storage ◽  
Additive Effect ◽  
Dormancy Release ◽  
Storage Location ◽  
Order Of Magnitude ◽  
In Fire ◽  
Seed Coats

Fire stimulates germination of most seeds in fire-prone vegetation. Fruits of Leucadendron (Proteaceae) are winged achenes or nutlets that correlate with their requirements for smoke and/or heat in promoting germination. We describe five possible smoke–heat dormancy-release/germination syndromes among plants, of which Leucadendron displays three (no response, smoke only, smoke and heat). As seed-coat thickness varies with seed-storage location (plant or soil) and morphology (winged or wingless), we tested its possible role in water uptake and germination. Species with winged seeds achieved 100% germination in the absence of smoke/heat, seed coats were an order of magnitude thinner, and their permeability greatly exceeded that of nutlets. As seed-coat thickness increased a) imbibitional water uptake declined at a decreasing rate, and b) the response to smoke, and to a lesser extent heat, increased linearly to reach levels of germination approaching those of winged seeds. For species responsive to smoke and heat, there was no additive effect when applied together, suggesting that they may have promoted the same physiological process. By what mechanisms a) the smoke response is greater the thicker the seed coat, and b) smoke chemicals could increase water permeability to explain the non-additive effect of smoke and heat, warrant further investigation.

scholarly journals The crypsis hypothesis explained: a reply to Jayasuriya et al. (2015)

2015 ◽  
Vol 25 (4) ◽  
pp. 402-408 ◽  
Author(s):  
Torbjørn R. Paulsen ◽  
Louise Colville ◽  
Matthew I. Daws ◽  
Sigrunn Eliassen ◽  
Göran Högstedt ◽  
...  
Keyword(s):  
Seed Coat ◽  
Generation Time ◽  
Dormancy Release ◽  
Hard Seed ◽  
Theory Of Evolution ◽  
Key Features ◽  
Evolution By Natural Selection ◽  
Hard Seed Coat ◽  
Seed Coats ◽  
By Products

AbstractIn imbibing seeds, resumption of metabolism leads to the unavoidable release of volatile by-products that are perceived as cues by rodent seed predators. The crypsis hypothesis proposes that the primary function of a water-impermeable, hard seed coat is to reduce rodent seed predation by rendering seeds olfactorily cryptic. In an opinion paper, Jayasuriya et al. (2015) find the crypsis hypothesis unscientific and ‘not consistent with Darwin's theory of evolution by natural selection’. It is unfortunate that Jayasuriya et al. (2015) did not appreciate that the crypsis hypothesis offers an alternative explanation for the evolution of water-impermeable seeds: released seed volatiles are cues used by rodents to locate seeds, and variation in seed-coat permeability leading to differences in seed volatile release represents the variable under selection. Furthermore, the sealing of water-impermeable seed coats imposes a cost of increased generation time and, therefore, dormancy-release mechanisms are expected to subsequently evolve in response to local environmental conditions. We also disagree with most other claims by Jayasuriya et al. (2015), who failed to appreciate how species with dimorphic seeds – one morph with permeable and the other with impermeable seed coats – benefit from rodent caching behaviour and population dynamics. We welcome this opportunity to clarify and elaborate on key features and the evolution of water-impermeable seed coats according to the crypsis hypothesis.

scholarly journals Structure, Water Permeability and Metabolism of Tilia miqueliana seeds during imbibition and dormancy release process

2020 ◽  
Author(s):  
YU WU ◽  
Bao Shen
Keyword(s):  
Seed Coat ◽  
Water Permeability ◽  
Low Permeability ◽  
Vascular Bundles ◽  
High Electron ◽  
Dormancy Release ◽  
Release Process ◽  
Main Obstacle ◽  
Structure Water ◽  
Mechanical Barrier

Abstract The mechanical barrier and low permeability of seed coat and endosperm may be the main obstacle to the imbibition and dormancy release of Tilia miqueliana seeds. MRI, SEM, TEM and PSD were used to study the structure, water permeability and metabolism of control seeds and H 2 SO 4 treated seeds during imbibition and dormancy release. The results showed that H 2 SO 4 treatment greatly improved the permeability of seed coat and endosperm, accelerated the metabolism of high electron density substances in endosperm cells, and shortened the process of seed dormancy release and germination. At the same time, protoplasts that eventually developed into vascular bundles were surprisingly found in cotyledons and radicles.

Relating Mechanical Changes at the Glass Transition with Water Absorption Behavior of Dry Legume Seeds

2010 ◽  
Vol 6 (4) ◽  
Author(s):  
Kelly A. Ross ◽  
Susan D. Arntfield ◽  
Stefan Cenkowski ◽  
Gary R. G. Fulcher
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Water Uptake ◽  
Seed Coat ◽  
Glassy State ◽  
Exponential Equation ◽  
Soaking Time ◽  
Legume Seeds ◽  
Seed Coats

This work provides a novel view of explaining water uptake behavior commonly observed in legume seeds. A model proposed by Peleg to describe the mechanical changes in biomaterials transitioning from a glassy state to a rubbery state was used to describe water uptake by legume seeds exhibiting a lag during imbibition and to characterize the mechanical changes of the seed coat as affected by soaking time. The seeds characterized by Peleg’s model possessed seed coats with a glass transition temperature higher than ambient soaking conditions. Alternatively, the water uptake behavior of legume seeds that did not exhibit a lag phase was characterized by an exponential equation used in polymer science to model solvent sorption by materials above their glass transition. A modified exponential equation was developed to model the mechanical behavior of these seed coats as affected by soaking time. Seeds characterized by the exponential equation possessed seed coats with a glass transition temperature near ambient soaking conditions. This work demonstrates, through the use of two separate models, water uptake behavior of legume seeds can be explained by the glass transition temperature of the seed coat.

scholarly journals An Untargeted Metabolomics Approach for Correlating Pulse Crop Seed Coat Polyphenol Profiles with Antioxidant Capacity and Iron Chelation Ability

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3833
Author(s):  
Fatma M. Elessawy ◽  
Albert Vandenberg ◽  
Anas El-Aneed ◽  
Randy W. Purves
Keyword(s):  
Antioxidant Capacity ◽  
Seed Coat ◽  
Iron Chelation ◽  
Iron Bioavailability ◽  
Untargeted Metabolomics ◽  
Black Bean ◽  
Pulse Crops ◽  
Pulse Crop ◽  
Seed Coats ◽  
Crop Seed

Pulse crop seed coats are a sustainable source of antioxidant polyphenols, but are typically treated as low-value products, partly because some polyphenols reduce iron bioavailability in humans. This study correlates antioxidant/iron chelation capabilities of diverse seed coat types from five major pulse crops (common bean, lentil, pea, chickpea and faba bean) with polyphenol composition using mass spectrometry. Untargeted metabolomics was used to identify key differences and a hierarchical analysis revealed that common beans had the most diverse polyphenol profiles among these pulse crops. The highest antioxidant capacities were found in seed coats of black bean and all tannin lentils, followed by maple pea, however, tannin lentils showed much lower iron chelation among these seed coats. Thus, tannin lentils are more desirable sources as natural antioxidants in food applications, whereas black bean and maple pea are more suitable sources for industrial applications. Regardless of pulse crop, proanthocyanidins were primary contributors to antioxidant capacity, and to a lesser extent, anthocyanins and flavan-3-ols, whereas glycosylated flavonols contributed minimally. Higher iron chelation was primarily attributed to proanthocyanidin composition, and also myricetin 3-O-glucoside in black bean. Seed coats having proanthocyanidins that are primarily prodelphinidins show higher iron chelation compared with those containing procyanidins and/or propelargonidins.

scholarly journals Effects of Different Pretreatments and Seed Coat on Dormancy and Germination of Seeds of Senna obtusifolia (L.) H.S. Irwin & Barneby (Fabaceae)

2016 ◽  
Vol 8 (2) ◽  
pp. 77
Author(s):  
Stephen I. Mensah ◽  
Chimezie Ekeke
Keyword(s):  
Sulfuric Acid ◽  
Seed Dormancy ◽  
Water Uptake ◽  
Seed Coat ◽  
Critical Factor ◽  
Potassium Nitrate ◽  
Ex Situ ◽  
Mechanical Resistance ◽  
Physical Dormancy ◽  
Senna Obtusifolia

<p class="1Body">The seed dormancy of <em>Senna obtusifolia</em> was investigated through various methods, namely pretreatments in concentrated sulfuric acid, 2% potassium nitrate (KNO<sub>3</sub>), 99% ethanol, 99% methanol, and in hydrogen perioxide; examination of the seed coverings; and the determination of water uptake by the seeds in order to ascertain the most effective technique for breaking dormancy and also determine the dormancy type. The results showed that sulfuric acid treatment recorded the highest germination (100%); followed by 2% hydrogen peroxide treatment (24%) in 15minutes immersion. The methanol and ethanol pretreatments gave 18.33% and 16.5% germinations respectively. Pretreatment in 2% potassium nitrate gave the lowest germination (8.50%), while the intact seeds of <em>S. obtusifiolia</em> (control) gave 0% germination. The anatomy of the seed coat indicated the presence of hard, thickened and specialized cells of cuticle, macrosclereids, osteoscereids, and disintegrated parenchyma layers. The water uptake of intact seeds was low (13.5%) after 24 hr imbibitions. These findings revealed that the seed coat acts as barrier to germination by preventing water absorption, possibly gaseous diffusion in and out of the seed and conferring mechanical resistance to the protrusion of embryo. Pretreatments, such as immersion in H<sub>2</sub>SO<sub>4 </sub>will soften the seed coat and permit germination. Seed dormancy in <em>S. obtusifolia </em>can be considered of physical nature and classified as physical dormancy. The results obtained in this study may serve as useful information in the production and improvement of <em>S. obtusifolia </em>seedlings, as knowledge on seed dormancy and germination is a critical factor and requirements to the understanding of the propagation of this plant either in situ or ex-situ, in view of the economic potentials/attributes of this species.</p>

scholarly journals Influence of lignin content in soybean seed coat on the incidence of the storage fungus Aspergillus flavus

2012 ◽  
Vol 34 (4) ◽  
pp. 541-548 ◽  
Author(s):  
Ísis Barreto Dantas ◽  
João Almir de Oliveira ◽  
Heloisa Oliveira dos Santos ◽  
Édila Vilela Resende Von Pinho ◽  
Sttela Dellyzete Veiga Franco da Rosa
Keyword(s):  
Electrical Conductivity ◽  
Aspergillus Flavus ◽  
Seed Coat ◽  
Seed Quality ◽  
Lignin Content ◽  
Soybean Seed ◽  
Storage Period ◽  
Seed Storage ◽  
Seed Health ◽  
Physiological Quality

Seed quality may be affected by several factors, including permeability, color, and lignin content in the seed coat. This study aimed at evaluating influence of lignin content in the tegument of seed samples of six different soybean cultivars, in which half of each sample was inoculated with the fungus Aspergillus flavus, on the physical and physiological quality, and on the seed health, during 180 days storage period, under cold chamber with controlled conditions of temperature and RH. For that, at each interval of 60 days, samples were removed, and the physiological quality of these seeds was assessed by means of moisture and lignin contents; and by tests of seed health, germination, and electrical conductivity. The moisture content of seeds remained constant during all storage period. In the seed health test, it was found that inoculation was efficient, once the minimum incidence of the fungus in the inoculated seeds was 85%. In the germination test, there was a trend of reduction on percentage germination with the increase in storage period. However, there was an increase on electrical conductivity of seeds assessed. It was concluded that there is no interference of the lignin content in the seed coat on the resistance to infection by the fungus Aspergillus flavus, even after seed storage for a period of 180 days.

scholarly journals Influence of Seed Coat Color Genes on Milling Qualities of Red Lentil (Lens culinaris Medik.)

2018 ◽  
Vol 10 (10) ◽  
pp. 88 ◽  
Author(s):  
Maya Subedi ◽  
Lope G. Tabil ◽  
Albert Vandenberg
Keyword(s):  
Seed Coat ◽  
Coat Color ◽  
Seed Coat Color ◽  
Milling Quality ◽  
Economic Trait ◽  
Milling Characteristics ◽  
Genotype Interaction ◽  
Dehulling Efficiency ◽  
Seed Characteristics ◽  
Seed Coats

Efficient milling is the key economic trait for the red lentil industry. Various seed characteristics including seed coat color can influence milling characteristics. Four basic seed coat ground colors (green, gray, tan, and brown) of 16 red lentil genotypes from a common genetic background were compared to determine the effect of seed coat color genes on three key milling quality traits: dehulling efficiency (DE), milling recovery (MR), and football recovery (FR). These genotypes were grown at two locations in Saskatchewan, Canada for two years. DE, MR, and FR results varied depending on the seed coat color conferred by specific genotypes. Green and gray seed coat color (homozygous recessive tgc allele) genotypes had significantly higher DE and MR percentages compared to brown or tan seed coat types (homozygous dominant Tgc allele) depending on genotype interaction with site-year. Seeds with brown or tan seed coats had significantly higher FR percentages in two site-years. Red cotyledon lentils with uniform shape and green or gray seed coat color might be more profitable for millers who wish to maximize DE and MR of red lentil, but brown seed coat color might be preferable in terms of FR.

scholarly journals Comparative seed coat anatomy of the genus Wollemia (Araucariaceae)

2020 ◽  
Vol 19 (2) ◽  
pp. 134-139
Author(s):  
A. S. Timchenko ◽  
A. N. Sorokin ◽  
N. S. Zdravchev ◽  
A. V. F. Ch. Bobrov ◽  
M. S. Romanov
Keyword(s):  
Seed Coat ◽  
Progressive Type ◽  
The Family ◽  
Transitional Type ◽  
Seed Coats

The seed coat anatomy of Wollemia nobilis W. G. Jones, K. D. Hill et J. M. Allen was carried out. In theresult of analysis of transverse sections of seeds the sufficient parenchymatization of seed coats and their differentiationinto three morphogenetic zones – the exotesta, the mesotesta and the endotesta was revealed. Such characters of thespermoderm as differentiation of the mesotesta into several topographic zones, presence of resin cavities in mesotesta, aswell as the participation of both exotesta and mesotesta in making the wing are treated as the archaic ones. The seeds of W.nobilis are of transitional type between exomesotestal and the exotestal type (according to Corner's typology). In generalthe seed coat structure of W. nobilis fits into the divercity of seed coats structure in the family Araucariaceae and is treatedas a progressive type within the family.

Structural aspects of dormancy in quinoa (Chenopodium quinoa): importance and possible action mechanisms of the seed coat

2015 ◽  
Vol 25 (3) ◽  
pp. 267-275 ◽  
Author(s):  
Diana Ceccato ◽  
Daniel Bertero ◽  
Diego Batlla ◽  
Beatriz Galati
Keyword(s):  
Seed Coat ◽  
Chenopodium Quinoa ◽  
Sowing Date ◽  
Sources Of Resistance ◽  
Action Mechanisms ◽  
Sowing Dates ◽  
Embryo Dormancy ◽  
Different Temperatures ◽  
Seed Coats ◽  
Structural Aspects

AbstractTwo possible sources of resistance to pre-harvest sprouting were evaluated in quinoa. They showed dormancy at harvest and significant variations in dormancy level in response to environmental conditions experienced during seed development. The aims of this work were to evaluate the importance of seed coats in the regulation of dormancy in this species, to investigate possible mechanisms of action and to assess association of seed coat properties with changes in dormancy level caused by the environment. Accessions Chadmo and 2-Want were grown under field conditions on different sowing dates during 2 years. Seed coats were manipulated and seed germination was evaluated at different temperatures. Seed coat perforation before incubation led to faster dormancy loss in both accessions. This effect decreased with delayed sowing date, and seeds expressed a level of dormancy not imposed by coats. This suggests the presence of embryo dormancy in the genus Chenopodium. Seeds of the accession 2-Want had a significantly thinner seed coat at later sowing dates, associated with a decreasing coat-imposed dormancy, but this pattern was not detected in Chadmo. The seed coat acts as a barrier to the release of endogenous abscisic acid (ABA) in quinoa, suggested by the increase in germination and a higher amount of ABA leached from perforated seeds. ABA is able to leach from seeds with an intact seed coat, suggesting that differences in seed coat thickness may allow the leakage of different amounts of ABA. This mechanism may contribute to the observed differences in dormancy level, either between sowing dates or between accessions.

scholarly journals Reproductive trajectories over decadal time-spans after fire for eight obligate-seeder shrub species in south-eastern Australia

2014 ◽  
Vol 62 (5) ◽  
pp. 369 ◽  
Author(s):  
Annette M. Muir ◽  
Peter A. Vesk ◽  
Graham Hepworth
Keyword(s):  
Seed Storage ◽  
Fire Frequency ◽  
Reproductive Maturity ◽  
South Eastern ◽  
Reproductive Response ◽  
Eastern Australia ◽  
Maturity Period ◽  
Fire Planning ◽  
In Fire ◽  
South Eastern Australia

Intervals between fires are critical for the persistence of obligate-seeding shrubs, and are often used in planning fires for fuel reduction and biodiversity conservation in fire-prone ecosystems worldwide. Yet information about the trajectories of reproductive performance for such species is limited and information is often qualitative. To test existing assumptions about reproductive maturity periods for eight obligate-seeding shrubs (with both canopy and soil seedbanks) in foothill forests of south-eastern Australia, we used a chronosequence approach, with sites from 2 years to >40 years post-fire. Quantitative measurements of flowering and fruiting were used to fit models of reproductive response in relation to time-since-fire for each species. Inferred reproductive maturity for each species, based on modelled times to reach 80% of maximum flower production, varied from 5 to 18 years post-fire. For a subset of three species, models predicted 80% maximum seed production occurring 1–7 years later than flowering. Our results confirmed or extended assumptions about post-fire reproductive maturity for these species, and provided a basis for improved incorporation of plant life-history in ecological fire planning. We infer that increased fire frequency makes one of our study taxa, Banksia spinulosa var. cunninghamii (Sieber ex Rchb.) A.S.George, vulnerable to decline because of its long reproductive maturity period and serotinous seed storage.

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