Red-light- and gibberellic-acid-enhanced ?-galactosidase activity in germinating lettuce seeds, cv. Grand Rapids

Planta ◽  
1981 ◽  
Vol 152 (5) ◽  
pp. 436-441 ◽  
Author(s):  
David W. M. Leung ◽  
J. Derek Bewley
Keyword(s):  
Gibberellic Acid ◽  
Red Light ◽  
Galactosidase Activity ◽  
Lettuce Seeds ◽  
Grand Rapids

scholarly journals Actions of Gibberellic Acid and Phytochrome on the Germination of Grand Rapids Lettuce Seeds

1974 ◽  
Vol 53 (2) ◽  
pp. 266-268 ◽  
Author(s):  
William Vidaver ◽  
A. I-Hsiung Hsiao
Keyword(s):  
Gibberellic Acid ◽  
Lettuce Seeds ◽  
Grand Rapids

Some aspects of the function of the endosperm during the germination of lettuce seeds

1974 ◽  
Vol 52 (5) ◽  
pp. 1117-1121 ◽  
Author(s):  
Henry L. Speer
Keyword(s):  
Lactuca Sativa ◽  
Red Light ◽  
Intact Seed ◽  
Lettuce Seeds ◽  
Grand Rapids

The response to red and far-red light of intact and punched seeds of Lactuca sativa var. Grand Rapids is compared. Punched seeds are fully responsive to red light after only 1 min of hydration; intact seeds require 15 min. Punching has no effect on the usual red and far-red light mediation of germination of these seeds. It does, however, raise the level of dark germination, indicating that there are at least two mechanisms by which the seed can germinate, only one of which is controlled by phytochrome.Treatment of seeds with dichloromethane enhances germination in seeds imbibed 1 min but not the penetration of arsenate, which is normally excluded by the intact seed. The detergent Brij greatly enhances the penetration of arsenate into the seed.

Characterization of SAN 9789-Stimulated Lettuce (Lactuca sativa) Seed Germination

Weed Science ◽  
1985 ◽  
Vol 33 (2) ◽  
pp. 160-164 ◽  
Author(s):  
Karl-Olof Widell ◽  
Christer Sundqvist ◽  
Hemming I. Virgin
Keyword(s):  
Abscisic Acid ◽  
Seed Germination ◽  
Lactuca Sativa ◽  
Red Light ◽  
Inhibitory Effect ◽  
Lettuce Seeds ◽  
Grand Rapids ◽  
Minor Degree ◽  
A Minor

Dark germination of light-requiring lettuce seeds (Lactuca sativaL. ‘Grand Rapids’) was stimulated by SAN 9789 [4-chloro-5-(methylamino-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone] and to a minor degree by BASF 13761 [4-chloro-5-methoxy-2-phenyl-3(2H)-pyridazinone] and BASF 44521 [4-chloro-5-methoxy-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone], but not by’ pyrazon [5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone], SAN 9785 [4-chloro-5-(dimethylamino)-2-phenyl-3 (2H)-pyridazinone], SAN 9774 [5-amino-4-chloro-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone], or SAN 6706 [4-chloro-5-(dimethylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone]. SAN 9789 stimulation was inhibited by cis-4-cyclohexene-1,2-dicarboximide (CHDC), and abscisic acid (ABA) at 1 × 10-4M. Red light nullified the inhibitory effect of CHDC (1 × 10-4M) but not the inhibitory effect of ABA (1 × 10-4M) on SAN 9789 stimulated germination. Gibberellic acid (GA3) and kinetin (6-furfurylaminopurine) increased the germination stimulatory effect of SAN 9789 in darkness. Temperatures above 25 C decreased the effect of SAN 9789, with a temperature of 35 C completely inhibiting germination. The inhibitory effect of CHDC was strongly decreased at temperatures below 20 C. SAN 9789-induced germination in darkness was always the same (25 to 26% units increase in germination) even though the red light-stimulated germination differed with the seed batch.

Seed water content in relation to phytochrome-mediated germination of lettuce seeds (Lactuca sativa L. var. Grand Rapids)

1971 ◽  
Vol 49 (1) ◽  
pp. 111-115 ◽  
Author(s):  
A. I-Hsiung Hsiao ◽  
William Vidaver
Keyword(s):  
Water Content ◽  
Lactuca Sativa ◽  
Red Light ◽  
Second Stage ◽  
Lettuce Seeds ◽  
Lactuca Sativa L ◽  
Grand Rapids ◽  
Two Stages ◽  
Seed Water Content ◽  
Stimulation Of

It is possible to distinguish two stages in the influence of light on the germination of Lactuca sativa var. Grand Rapids (lettuce) seeds. The first stage, which is represented by the photoactivation or transformation of phytochrome, requires only a relatively low seed water content. Slightly higher seed water content is required for maximum far-red light repression, than for red light stimulation of germination. The second stage is indicated by the well-known situation in which previous red irradiations of the seeds can enhance germination but this takes place only with relatively high seed water content. Phototransformed phytochrome appears to persist and to be susceptible to photoreversal for at least 24 h after irradiation in the seeds with relatively low water content.

Acidification, growth promoter, and red light effects on germination of skotodormant lettuce seeds (Lactuca sativa)

1984 ◽  
Vol 62 (6) ◽  
pp. 1108-1115 ◽  
Author(s):  
Andrew I. Hsiao ◽  
William Vidaver ◽  
William A. Quick
Keyword(s):  
Lactuca Sativa ◽  
Red Light ◽  
Critical Factor ◽  
Growth Promoter ◽  
Growth Promoters ◽  
Lettuce Seeds ◽  
Grand Rapids ◽  
Increased Sensitivity ◽  
Light Effects ◽  
Different Sources

Increasing the period of dark storage (DS) within a uniform seed lot of lettuce (Lactuca sativa L. cv. Grand Rapids) increased the degree of secondary dormancy (skotodormancy) induced, as evidenced by a loss of sensitivity to red light (R) and growth promoters such as gibberellin A3 (GA3), kinetin, thiourea, and ethylene. Differential degrees of skotodormancy were induced in lettuce seeds from three different sources (lot I < lot II < lot III). Either R or GA3 significantly increased the germination of skotodormant seeds if seeds were first immersed in strongly acidic solutions (pH ≤ 3.0) and then rinsed with water. The critical factor was found to be pH, not ionic strength. Promotion of germination by R or GA3 was positively related to increasing acidity, and also to the duration of DS. Sensitivity of the germination response to acid immersion varied with the seed lots, as little as 1 s being effective with some seeds. Acid treatment thus enables skotodormant seeds to recover much of their responsiveness to R and GA3. Extended DS (21 days) produced such pronounced skotodormancy (seed lot III) that acid immersion followed by usual R and GA3 produced only 10% germination. Continuous R or a seed-piercing treatment produced complete germination in otherwise skotodormant seeds. Responsiveness of germination to thiourea, kinetin, and ethylene, however, was not regained by treatment with acid. The action of these three chemicals on skotodormant seeds thus seems to be dependent on an active phytochrome and GA3-sensitive system. Acid-immersion treatments appear primarily to weaken membrane barriers of the endosperm cells, with resulting increased sensitivity of seeds to R treatment and GA3 penetration.

Evidence for inhibitor involvement in thermodormancy of Grand Rapids lettuce seeds

1991 ◽  
Vol 1 (4) ◽  
pp. 263-267 ◽  
Author(s):  
J. G. Chris Small ◽  
Yitzchak Gutterman
Keyword(s):  
High Temperature ◽  
Temperature Treatment ◽  
Small Extent ◽  
High Temperature Treatment ◽  
Ultraviolet Region ◽  
Distilled Water ◽  
Osmotic Effect ◽  
Lettuce Seeds ◽  
Grand Rapids ◽  
Lower Temperature

AbstractProlonged imbibition and incubation of lettuce seeds at a supraoptimal temperature induces secondary dormancy. Such seeds no longer germinate when returned to conditions optimal for germination of non-dormant seeds. The possibility that inhibitors are involved in the induction of thermodormancy was investigated.Washing of thermodormant seeds restored germination to a small extent. However, continuous leaching of seeds during high-temperature treatment with distilled water, largely prevented the induction of thermodormancy. Such seeds were qualitatively similar to nondormant seeds, i.e. they required only light to germinate at a lower temperature and germinated in the dark if given GA3. The germination water from thermodormant seeds inhibited the germination of non-dormant lettuce seeds. The inhibition was not an osmotic effect. Absorbance in the ultraviolet region was higher in germination water from thermodormant seeds than that of non-dormant seeds. It is concluded that inhibitors are involved in the induction of thermodormancy of lettuce seeds.

scholarly journals Induction of Dormancy in Nondormant Seeds

1994 ◽  
Vol 119 (3) ◽  
pp. 408-413 ◽  
Author(s):  
Anwar A. Khan
Keyword(s):  
Abscisic Acid ◽  
Lycopersicon Esculentum ◽  
Gibberellic Acid ◽  
Lactuca Sativa ◽  
Daucus Carota ◽  
Apium Graveolens ◽  
Lettuce Seeds ◽  
Moist Chilling ◽  
Dormancy Induction ◽  
Ga Biosynthesis

A gibberellic acid (GA) biosynthesis inhibitor, tetcyclacis, induced dormancy in nondormant seeds of lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), pepper (Capsicum annuum L.), carrot [Daucus carota var. sativus (Hoffn.)], onion (Allium cepa L.), celery (Apium graveolens L.), and impatiens (Impatiens novette), as most of the seeds failed to germinate after washing under conditions that permitted germination before dormancy induction. In lettuce seeds, tetcyclacis and paclobutrazol were more effective in inhibiting germination in light than in darkness. A 16- to 24-h soak treatment with tetcyclacis was sufficient to induce dormancy in nearly all seeds. Tetcyclacis failed to induce dormancy if applied after 6 h presoak in water. Dormancy induced by tetcyclacis was released by GA4+7 (a mixture of gibberellin A4 and A7), light, and moist-chilling treatments. When GA4+7 was applied with tetcyclacis, dormancy induction was prevented under both favorable, e.g., 25C, and unfavorable, e.g., 5C, or low water potential (Ψ), germination conditions. Unlike tetcyclacis, abscisic acid (ABA) failed to induce dormancy in lettuce seeds. Thermodormancy induction in lettuce seeds at 35C was prevented by fluridone. However, neither ABA nor tetcyclacis countered its effect. Dormancy was also induced in lettuce seeds by ancymidol, flurprimidol, or paclobutrazol. Dormancy induced by tetcyclacis in pepper, tomato, carrot, and onion seeds was released by GA4+7, but not by irradiation or moist-chilling. Chemical names used: 5-(4-chlorophenyl)-3, 4, 5, 9, 10-pentaazatetracyclo [5.4.102,6.08,11]-dodeca-3, 9-diene (tetcyclacis); 1-(4-chlorophenyl)-4, 4-dimethyl-2-(1H-1, 2, 4-triazole-1-yl)-3-pentanol (paclobutrazol); α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidine methanol (ancymidol); α-(1-methyl)-α-[4-(trifluoromethoxy) phenyl]-5-pyrimidine-methanol (flurprimidol); 1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4 (1H)-pyridinone (fluridone).

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