Dormancy Breaking and Stimulation of Apical and Basal Sugarcane Stem to Increase Multiplication Index

Effects of ethylene and KNO3on the germination of dormant common lambsquarters (Chenopodium albumL. # CHEAL) seed were studied under controlled environmental conditions. Ethylene, applied in the gaseous form or as an aqueous solution of ethephon (2-chloroethylphosphonic acid), was able to overcome the dormancy of over 70% of the seed. The optimum concentrations of ethylene and ethephon were 10 μL·L-1and 100 mg·L-1, respectively. The dormancy-breaking action of ethylene was dependent on the availability of nitrate. Hence, seed containing a high level of endogenous nitrate responded readily to ethylene, whereas nitrate-deficient seed required a combined application of ethylene and nitrate. Stimulation of seed germination by ethylene was observed in soil at all depths studied (up to 15 cm). The sensitivity of seed to ethylene increased upon imbibition to reach a peak on the third day, followed by a steady decline. Consequently, the greatest promotion of germination occurred when ethylene was administered during the first 3 to 4 days of imbibition. The loss of seed sensitivity was neither preempted nor overcome by an exogenous supply of KNO3, and may imply that the seed had passed into secondary dormancy. The present findings could form the basis for the use of ethylene to accomplish commercially significant promotion of germination in the field and thus improve the efficiency of the control of common lambsquarters.

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Low temperature stimulates spatial molecular reprogramming of the Arabidopsis seed germination programme

Seed Science Research ◽

10.1017/s0960258519000266 ◽

2020 ◽

Vol 30 (1) ◽

pp. 2-12

Author(s):

Jack Mitchell ◽

Nur K. Mukhtar ◽

George W. Bassel

Keyword(s):

Low Temperature ◽

Promoter Activity ◽

Time Course ◽

Cell Types ◽

Protein Abundance ◽

Cell Type ◽

Dormancy Breaking ◽

Environment Temperature ◽

Whole Seed ◽

Stimulation Of

AbstractThe timing of the germination of seeds is highly responsive to inputs from the environment. Temperature plays a key role in the control of germination, with low temperatures acting to stimulate this developmental transition in many species. In Arabidopsis, extensive gene expression changes have been reported at the whole seed level in response to cold, while much less is known about their spatial distribution across the diverse cell types of the embryo. In this study we examined the spatiotemporal patterns of promoter activity and protein abundance for key gibberellic acid (GA) and abscisic acid (ABA) factors which regulate the decision to germinate both during a time course of germination and in response to cold. Low temperature stimulated the spatial relocalization of these factors to the vasculature. The response of these seeds to dormancy-breaking stratification treatments therefore stimulates the distribution of both positive (GA) and negatively acting (ABA) components to this same cell type. This altered spatial pattern persisted following the transfer of seeds to 22°C, as well as after their rehydration, indicating that this alteration is persistent. These observations suggest that the vasculature plays a role in the low temperature-mediated stimulation of germination in this species, while novel cell types are recruited to promote germination in response to stratification.

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Effects of 5-5'-Diphenyl-2-thiohydantoin (DPTH) and Thyroxine on the Ultrastructure and Chemical Composition of Rat Liver

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066917 ◽

1971 ◽

Vol 29 ◽

pp. 570-571

Author(s):

E. A. Elfont ◽

R. B. Tobin ◽

D. G. Colton ◽

M. A. Mehlman

Keyword(s):

Chemical Composition ◽

Rat Liver ◽

Future Study ◽

Mode Of Action ◽

Liver Mitochondria ◽

Rat Liver Mitochondria ◽

Effective Inhibitor ◽

Biochemical Effects ◽

Glycerophosphate Dehydrogenase ◽

Stimulation Of

Summary5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred daily for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biocheailcal analyses, while the rest was prefixed in buffered 3.5X glutaraldehyde (390 mOs) and post-fixed in buffered 1Z OsO4 (376 mOs). Tissues were embedded in Araldlte 502 and the sections examined in a Zeiss EM 9S.Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.

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Gap junctions in the prothoracic glands of the tobacco hornworm, Manduca sexta

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123933 ◽

1992 ◽

Vol 50 (1) ◽

pp. 706-707

Author(s):

Ji-da Dai ◽

M. Joseph Costello ◽

Lawrence I. Gilbert

Keyword(s):

Gap Junctions ◽

Small Molecules ◽

Manduca Sexta ◽

Freeze Fracture ◽

Cell Communication ◽

Cellular Level ◽

Thin Sections ◽

Prothoracic Glands ◽

Polyhydroxylated Steroids ◽

Stimulation Of

Insect molting and metamorphosis are elicited by a class of polyhydroxylated steroids, ecdysteroids, that originate in the prothoracic glands (PGs). Prothoracicotropic hormone stimulation of steroidogenesis by the PGs at the cellular level involves both calcium and cAMP. Cell-to-cell communication mediated by gap junctions may play a key role in regulating signal transduction by controlling the transmission of small molecules and ions between adjacent cells. This is the first report of gap junctions in the PGs, the evidence obtained by means of SEM, thin sections and freeze-fracture replicas.

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