Some reflections on the relationship between endogenous hormones and light-mediated seed dormancy

1992 ◽  
Vol 11 (3) ◽  
pp. 239-248 ◽  
Author(s):  
Tudor H. Thomas
Keyword(s):  
Seed Dormancy ◽  
Endogenous Hormones ◽  
The Relationship

A study of the relationship between seed dormancy and pentose phosphate pathway activity in Avena fatua

1983 ◽  
Vol 61 (3) ◽  
pp. 667-670 ◽  
Author(s):  
E. P. Fuerst ◽  
M. K. Upadhyaya ◽  
G. M. Simpson ◽  
J. M. Naylor ◽  
S. W. Adkins
Keyword(s):  
Seed Dormancy ◽  
Pentose Phosphate Pathway ◽  
Krebs Cycle ◽  
Pure Line ◽  
Pentose Phosphate ◽  
Avena Fatua ◽  
Wild Oats ◽  
Gibberellin Treatment ◽  
The Relationship ◽  
Increased Activity

The hypothesis that loss of seed dormancy is associated with an increased activity of the pentose phosphate pathway (PPP) relative to glycolysis and the Krebs cycle was tested. The PPP activity was monitored by measuring the C6/C1 ratio in embryos excised from incubated caryopses of two genetically pure nondormant (ND) lines and in three dormant (D) lines of Avena fatua L., the wild oat. The C6/C1 ratios of all lines were similar at the commencement of incubation. In the two ND lines the ratio increased steadily prior to and during emergence of the radicle. In the three D lines the ratio increased during the first 24 h and then remained almost constant; there was no germination. When gibberellin treatment was used to overcome dormancy in the D lines, the C6/C1 ratio increased during the first 24 h in two of the lines and continued to increase parallel to germination in a manner similar to normal germination in ND lines. In the third D line, despite loss of dormancy from gibberellin treatment, the ratio did not increase after 24 h. Loss of dormancy during dry storage of seeds of a D-type pure line was accompanied by an increase in the C6/C1 ratio, as measured in freshly imbibed seeds. This indicates a decreased activity of the PPP relative to glycolysis and the Krebs cycle. These findings are contrary to Roberts's hypothesis that loss of dormancy in wild oats is associated with a relative decrease in the C6/C1 ratio.

scholarly journals Storage Temperature Affects Sexual Potato Seed Dormancy

HortScience ◽  
1996 ◽  
Vol 31 (1) ◽  
pp. 99-101 ◽  
Author(s):  
Noël Pallais ◽  
José Santos-Rojas ◽  
Rosario Falcón
Keyword(s):  
Solanum Tuberosum ◽  
Seed Dormancy ◽  
Seed Quality ◽  
Storage Temperature ◽  
Dry Weight ◽  
Weight Basis ◽  
Mother Plant ◽  
Potato Seed ◽  
Dry Storage ◽  
The Relationship

Sexual potato (Solanum tuberosum L.) seeds require many months of afterripening in dry storage to completely lose dormancy and germinate readily at >25C. We examined the relationship between storage temperature and seed dormancy, as assessed by the percentage of germination after 4 days. Two F1 hybrid lots of `Desiree' × 7XY.1 were used; one seed lot was produced by carefully removing half of the developing tubers from the mother plant during seed development, and the control remained undisturbed. Seeds were stored with 3.4% moisture (dry-weight basis) at 10, 20, 30, 40, and 50C and were tested eight times during 29 months for daily germination at 27/40C (21/3 h) for the first 8 days, followed by 6 days at 17C. After 29 months of storage, final germination was <97% only when control seeds were stored at 50C, in which germination was 72%. Germination after 4 days increased curvilinearly with increasing storage temperature, and both seed lots similarly lost dormancy (germination >90%) after 10 months at 40C. Optimum germination levels were maintained after 29 months at 40C. Seeds stored at 50C never completely lost dormancy, and after 7 months of storage, germination at 4 days gradually decreased to zero. Dormancy was eventually lost after 29 months in most seeds stored at <40C, and differences between seed lots suggest that removing tubers from the mother plant increased dormancy. We conclude that dry potato seeds can be safely afterripened at temperatures up to 40C; lower temperatures slow the rate of dormancy loss, and higher ones are detrimental to seed quality.

Uterine blood flow in relation to endogenous hormones during estrous cycle and early pregnancy

1983 ◽  
Vol 245 (6) ◽  
pp. R843-R849 ◽  
Author(s):  
H. Roman-Ponce ◽  
D. Caton ◽  
W. W. Thatcher ◽  
R. Lehrer
Keyword(s):  
Blood Flow ◽  
Estrous Cycle ◽  
Early Pregnancy ◽  
Significant Relationship ◽  
Peripheral Blood ◽  
Endogenous Hormones ◽  
Uterine Blood Flow ◽  
Data Support ◽  
The Relationship

To evaluate the extent to which endogenous hormones in peripheral blood can account for uterine blood flow (UBF), rates of blood flow and concentrations of estrone (E1), estradiol (E2), and progesterone (P4) were measured simultaneously in four sheep during the estrous cycle and the first 3 wk of pregnancy. During the estrous cycle, UBF was inversely related to the concentration of P4 (P less than 0.01) and directly related to (E1 + E2)/P4 (P less than 0.01). There was no animal in which UBF was related to estrogen alone. No statistically significant relationship between endogenous hormones and UBF was detected in any ewe during the first 3 wk of pregnancy. Data support the idea that UBF varies during the estrous cycle in relation to peripheral concentrations of P4 and (E1 + E2)/P4 but leaves open the nature of the relationship in early pregnancy.

scholarly journals Seed dormancy varies widely among Arabidopsis thaliana populations both between and within Fennoscandia and Italy

2021 ◽  
Author(s):  
Giulia Zacchello ◽  
Svenja Bomers ◽  
Cecilia Böhme ◽  
Froukje Postma ◽  
Jon Agren
Keyword(s):  
Climate Change ◽  
Arabidopsis Thaliana ◽  
Seed Dormancy ◽  
Climatic Factors ◽  
Summer Temperature ◽  
Population Variation ◽  
Life History Trait ◽  
Adaptive Potential ◽  
Climatic Regions ◽  
The Relationship

The timing of germination is a key life-history trait in plants, which is strongly affected by the strength of seed dormancy. Continental-wide variation in seed dormancy has been related to differences in climate and the timing of conditions suitable for seedling establishment. However, for predictions of adaptive potential and consequences of climatic change, information is needed regarding the extent to which seed dormancy varies within climatic regions and the factors driving such variation We planted 17 Italian and 28 Fennoscandian populations of Arabidopsis thaliana in the greenhouse and at two field sites in Italy and Sweden. To identify possible drivers of among-population variation in seed dormancy, we examined the relationship between seed dormancy and climate at the sites where populations were originally sampled. Seed dormancy was on average stronger in the Italian compared to the Fennoscandian populations, but also varied widely within both regions. Estimates of seed dormancy in the three maternal environments were positively correlated, but seeds had on average stronger dormancy when produced in the greenhouse than at the two field sites. Among Fennoscandian populations, seed dormancy tended to increase with increasing summer temperature and decreasing precipitation at the site of origin. In the smaller sample of Italian populations, no significant association was detected between mean seed dormancy and climate at the site of origin. The correlation between seed dormancy and climatic factors in Fennoscandia suggests that at least some of the among-population variation is adaptive and that climate change will affect selection on this trait.

Hardseededness in annual clovers: variation between populations from wet and dry environments

2002 ◽  
Vol 53 (7) ◽  
pp. 821 ◽  
Author(s):  
Hayley C. Norman ◽  
Philip S. Cocks ◽  
Nick W. Galwey
Keyword(s):  
Seed Dormancy ◽  
Summer Rainfall ◽  
Optimal Time ◽  
Collection Site ◽  
The Third ◽  
Annual Legumes ◽  
Risk Of Mortality ◽  
The Relationship ◽  
Collection Sites

Annual legumes rely on hardseededness, a form of seed dormancy, to spread the risk of mortality associated with germination and to encourage germination at the optimal time in a season. This paper examines seed softening strategies of a number of clover (Trifolium) species collected over a range of environments. Three hypotheses are tested. The first is that within species, long-term hardseededness increases with aridity due to the greater chance of failure to reproduce in dry environments. It is tested by comparing seed softening patterns of populations of a number of clover species collected from a range of environments. The second hypothesis, that annual legumes from dry environments have a smaller subset of seed softening strategies than legumes from wetter environments, is tested by comparing the range of seed softening patterns from all species found at collection sites. The third hypothesis is that within-year patterns of seed softening that prevent germination after summer rainfall may partially substitute for long-term hardseededness. It is tested by examining the relationship between within-year hardseededness and between-year hardseededness. Accessions of the same species from different collection sites differed in both within-year pattern of seed softening and long-term hardseededness but there was little evidence that these differences were between ecotypes. Different species from the same collection site did not have similar seed softening strategies, and seed softening strategies of clovers from dry sites were as variable as those from wetter environments. Within-year pattern of seed softening does not appear to substitute for between-year hardseededness as a dormancy strategy.

scholarly journals A novel biomarker for anti-androgenic activity in placenta reveals risks of urogenital malformations

Reproduction ◽  
2015 ◽  
Vol 149 (6) ◽  
pp. 605-613 ◽  
Author(s):  
Juan P Arrebola ◽  
José M Molina-Molina ◽  
Mariana F Fernández ◽  
Jose M Sáenz ◽  
Esperanza Amaya ◽  
...  
Keyword(s):  
Reproductive Tract ◽  
Environmental Pollutants ◽  
Endogenous Hormones ◽  
Reproductive Disorders ◽  
Hplc Fraction ◽  
Novel Approach ◽  
Androgenic Activity ◽  
Normal Phase Hplc ◽  
The Relationship ◽  
Control Study

It has been hypothesized that the rise in male reproductive disorders over recent decades may at least be partially attributable to environmental factors, including chemical exposures, but observed associations with single chemicals were rather weak. The aim of this case–control study was to explore the relationship between exposure to mixtures of (anti-)androgenic chemicals during pregnancy and the risk of cryptorchidism and/or hypospadias in offspring, using the total effective xenobiotic burden of anti-androgens (TEXB-AA) as a biomarker. A subsample of 29 cases (16 of cryptorchidism, 12 of hypospadias, and one of both disorders) and 60 healthy controls was nested in a cohort of male newborns recruited between October 2000 and July 2002. The (anti-)androgenic activity of placenta samples collected at delivery was assessed using TEXB-AA biomarker, combined with a bioassay-directed fractionation protocol that separated endogenous hormones from most (anti-)androgenic chemicals by normal-phase HPLC. The bioassay measures the androgen-induced luciferase activity and the inhibition of this pathway by (anti-)androgens. First, we collected 27 HPLC fractions in each placenta extract, which were all tested in the bioassay. The multivariable statistical analyses indicated a statistically significant positive dose–response association between the potent anti-androgenic activity of the HPLC fraction collected during minutes 1–2 (F2) and the risk of malformations (odds ratio: 2.33, 95% CI: 1.04–5.23). This study represents a novel approach for the estimation of combined effects of the total anti-androgenic load and the associations suggest an effect of environmental pollutants on the development of fetal reproductive tract.Free Spanish abstract: A Spanish translation of this abstract is freely available athttp://www.reproduction-online.org/content/149/6/605/suppl/DC1.

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