Abscisic Acid and Xanthoxin Contents in the Long-Day Plant Lolium temulentum L. In Relation to Daylength

1977 ◽  
Vol 4 (2) ◽  
pp. 217 ◽  
Author(s):  
RW King ◽  
LT Evans ◽  
RD Firn
Keyword(s):  
Abscisic Acid ◽  
Liquid Chromatography ◽  
Shoot Apex ◽  
Gas Liquid Chromatography ◽  
Consistent Effect ◽  
Lolium Temulentum ◽  
Long Day ◽  
Inductive Photoperiod ◽  
Endogenous Aba

In L. temulentum L., flowering can be inhibited by application of abscisic acid (ABA) close to the shoot apex towards the end of an exposure to a single inductive long day. However, analysis by gas-liquid chromatography showed that the contents of endogenous ABA and xanthoxin in L. temulentum leaves are not consistently changed after an inductive photoperiod. Apex extractions carried out when (�)-ABA application near the apex is most inhibitory to flowering also showed no consistent effect of daylength on the content of ABA which was, however, much higher than in leaves. Thus it is unlikely that induction of flowering in L. temulentum by exposure to long days is due to changes in the endogenous levels of ABA and xanthoxin in the leaves or of ABA in the shoot apex.

Seasonal variation of abscisic acid in the dormant shoots of Douglas-fir

1979 ◽  
Vol 57 (5) ◽  
pp. 534-538 ◽  
Author(s):  
Joe E. Webber ◽  
Murray L. Laver ◽  
Joe B. Zaerr ◽  
Denis P. Lavender
Keyword(s):  
Abscisic Acid ◽  
Liquid Chromatography ◽  
Seasonal Variation ◽  
Internal Standard ◽  
Close Correlation ◽  
Douglas Fir ◽  
Gas Liquid Chromatography ◽  
Bud Burst ◽  
Liquid Chromatography Mass Spectrometry ◽  
Layer Chromatography

The occurrence of abscisic acid (ABA) in the dormant shoots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) was confirmed by bioassay, thin-layer chromatography, gas–liquid chromatography, and gas–liquid chromatography – mass spectrometry. Seasonal variation of ABA in the buds, leaves, and stems was then determined using 2-trans-ABA as an internal standard. Concentrations of ABA were highest in the autumn for buds (2.1 μg/g) and needles (0.79 μg/g) and highest in January for stems (0.34 μg/g). The lowest concentrations for all tissues were in February and March, before bud burst. Close correlation of levels of ABA with previously measured physiological evidence of growth and metabolic activity suggests a possible role in the dormancy cycle of Douglas-fir.

The Acceleration of Primordium Initiation as a Component of Floral Evocation in Lolium temulentum L

1996 ◽  
Vol 23 (5) ◽  
pp. 569 ◽  
Author(s):  
LT Evans ◽  
C Blundell
Keyword(s):  
Shoot Apex ◽  
Floral Development ◽  
Growth Retardant ◽  
Leaf Primordium ◽  
Essential Component ◽  
Lolium Temulentum ◽  
Long Day ◽  
External Sign ◽  
Floral Evocation

An acceleration of leaf primordium initiation by the shoot apex frequently follows floral evocation, but after varying intervals. The purpose of the experiments reported here was to define more closely the relation between this reduction of the plastochron and floral evocation, using the long day (LD) plant Lolium temulentum grown under closely controlled conditions.The acceleration begins at floral evocation, on the day after the first LD exposure, and increases after exposure to additional LDs. However, plants too young to be florally evoked by one LD nevertheless manifested an acceleration of primordium initiation, so the acceleration alone is not sufficient for evocation. Single applications of highly florigenic gibberellins (GAs), such as GA5, also accelerate the initiation of primordia and floral development, more so than does the weakly florigenic GA1. By contrast, single applications of the growth retardant Trinexapac-ethyl (CGA 163'935) to plants given one LD largely prevented the acceleration of primordium initiation but without inhibiting floral development. Thus, although the acceleration of primordium initiation by LD or by GA application is the first external sign of floral evocation in L. temulentum, it is neither a sufficient nor an essential component of it.

Abscisic acid concentration in Douglas-fir needles in relation to lifting date, cold storage, and postplanting vigor of seedlings

1987 ◽  
Vol 17 (5) ◽  
pp. 383-387 ◽  
Author(s):  
Pasi Puttonen
Keyword(s):  
Abscisic Acid ◽  
Liquid Chromatography ◽  
Acid Concentration ◽  
High Performance ◽  
Storage Conditions ◽  
Gas Liquid Chromatography ◽  
Light Storage ◽  
C Storage ◽  
Polyethylene Bags

Spring-lifted seedlings were grown in pots in the field and, after a natural fall photoperiod, exposed to three 25-day cold (+4 °C) storage treatments and two lifting times, mid-November and mid-January. The storage treatments were light storage in pots, dark storage in pots, and bareroot storage in polyethylene bags in the dark. In a second experiment, an extended fall photoperiod treatment was applied to seedlings that were then stored in pots and subjected to the same light and dark treatments above. In both experiments, needle samples were taken four times during and after the treatments for abscisic acid assay. Abscisic acid concentrations were determined using gas liquid chromatography after purification with high performance liquid chromatography. Lifting times and storage treatments did not result in statistically significant differences in abscisic acid concentrations. However, there were treatment differences in characteristics of postplanting performance. Mid-November lifting resulted in reduced survival and a greater number of days to bud flush compared with the mid-January lifting results. The extended fall photoperiod material produced similar results to the natural fall photoperiod material. The failure to detect a relationship between needle abscisic acid concentration and seedling vigor may have been due to a transitory role of abscisic acid in the storage conditions studied. The quantification method for abscisic acid is insensitive and laborious for practical seedling testing.

scholarly journals Inflorescence Initiation in Lolium Temulentum L. X. Changes in 32p Incorporation into Nucleic Acids of the Shoot Apex at Induction

1967 ◽  
Vol 20 (1) ◽  
pp. 13 ◽  
Author(s):  
AHGC Rijven ◽  
LT Evans
Keyword(s):  
Nucleic Acids ◽  
Shoot Apex ◽  
Floral Induction ◽  
Transient Increase ◽  
Lolium Temulentum ◽  
Long Day ◽  
32P Incorporation ◽  
Summit Region

Previous studies have shown an increase in RNA at the shoot apex of L. temulentum following floral induction, detectable chemically 2 days after induction, and by histochemical means after 1 day. Here, a transient increase in the incorporation of 32P, applied to leaves, into nucleic acids at the apex is shown to occur at about the time when the long-day stimulus is estimated to reach the shoot apex. The increased 32p incorporation due to the long-day exposure occurs throughout the apex, and is not confined to the summit region. Most of the 32p was incorporated into RNA.

Early increased expression of a cyclin-dependant protein kinase (LtCDKA1;1) during inflorescence initiation of the long day grass Lolium temulentum

2013 ◽  
Vol 40 (10) ◽  
pp. 986 ◽  
Author(s):  
Greg F. W. Gocal ◽  
Rod W. King
Keyword(s):  
Cell Division ◽  
Shoot Apex ◽  
Target Cells ◽  
Serine Threonine Kinase ◽  
Lolium Temulentum ◽  
Apical Dome ◽  
Long Day ◽  
Vegetative Shoot Apex ◽  
Weak Expression

Knowing where and when different genes express at the shoot apex during the transition to flowering will help in understanding this developmental switch. The CDKA family of serine/threonine kinase genes are appropriate candidates for such developmental switching as they are involved in the regulation of the G1/S and G2/M boundaries of the cell cycle (see review by Dudits et al. 2007) and so could regulate increases of cell division associated with flowering. Furthermore, in rice stems the gibberellin (GA) class of plant growth regulators rapidly upregulate CDKA expression and cell division. Thus, CDKA expression might be linked to the florigenic action of GA as a photoperiodically-generated, signal. For the grass Lolium temulentum L., we have isolated an LtCDKA1;1 gene, which is upregulated in shoot apices collected soon after the start of a single florally inductive long day (LD). In contrast to weak expression of LtCDKA1;1 in the vegetative shoot apex, in situ and PCR-based mRNA assays and immunological studies of its protein show very rapid increases in the apical dome at the time that florigenic signals arrive at the apex (<6 h after the end of the LD). By ~54 h LtCDKA1;1 mRNA is localised to the floral target cells, the spikelet primordia. Later both LtCDKA1;1 mRNA and protein are most evident in floret meristems. Only ~10% of cells within the apical dome are dividing at any time but the LD increase in LtCDKA1;1 may reflect an early transient increase in the mitotic index (Jacqmard et al. 1993) as well as a later increase when spikelet primordia form. Increased expression of an AP1-like gene (LtMADS2) follows that of LtCDKA1;1. Overall, LtCDKA1;1 is a useful marker of both early florigenic signalling and of later morphological/developmental aspects of the floral transition.

Shoot Apex Sugars in Relation to Long-Day Induction of Flowering in Lolium temulentum L

1991 ◽  
Vol 18 (2) ◽  
pp. 121 ◽  
Author(s):  
RW King ◽  
LT Evans
Keyword(s):  
Flux Density ◽  
Shoot Apex ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Sucrose Content ◽  
Inflorescence Development ◽  
Lolium Temulentum ◽  
Long Day ◽  
Floral Evocation

Inflorescence initiation in Lolium temulentum is induced by a single long day with a photoperiod extension of 16 h under low photon flux density (12 μmol PAR m-2 s-1) from incandescent lamps. Under these conditions the content of sucrose, the predominant free sugar in the shoot apex, fluctuates diurnally in the same way as in short day apices. There was no evidence of a greater apical sucrose content at any time during the long day or in the following period of high irradiance when floral evocation occurs. Thereafter, however, the diurnal fluctuation in apical sucrose content became more pronounced. Increasing the sugar supply to the apex by raising the photon flux density during the daily light period did not lead to flowering of non-induced plants; nor did the high contents of apical sugars reached in apices cultured in vitro on 5% sucrose medium. By contrast, when apices were excised after receipt of the floral stimulus from long day leaves, increase in the sugar content enhanced inflorescence development in vitro, this response being most pronounced after the inflorescences were initiated. Thus, floral evocation in L. temulentum does not require an increase in the content of sucrose at the apex although inflorescence development is highly responsive to it. When photoperiodic extensions with incandescent or fluorescent lamps were compared for their effects on apical sugars and flowering response, there was no interaction between light quality and photon flux density. Thus the shoot apex response to the low irradiance, photoperiodic time-measurement processes of leaves is distinct from the apical response to sugar supply. In Lolium temulentum floral evocation is controlled by the photoperiodic processes, the response to which is amplified by high sugar supplies but not replaced as it is in Sinapis alba.

The effect of lettuce seed extracts on lettuce seed germination

1975 ◽  
Vol 53 (7) ◽  
pp. 593-599 ◽  
Author(s):  
Henry L. Speer ◽  
Dorothy Tupper
Keyword(s):  
Abscisic Acid ◽  
Liquid Chromatography ◽  
Seed Germination ◽  
Seed Coat ◽  
Gas Liquid Chromatography ◽  
Lettuce Seed ◽  
Lettuce Seeds ◽  
Grand Rapids ◽  
Lettuce Seed Germination ◽  
Seed Extracts

Lettuce seeds (Lactuca sativa var. Grand Rapids) were found to contain inhibitory substances, one of which is probably abscisic acid. Extracts from seeds were characterized by gas–liquid chromatography, and peaks coincident with abscisic acid were found.The germination water surrounding seeds made secondarily dormant was subjected to gas–liquid chromatography and was also found to contain peaks coincident with abscisic acid. It was also determined that the inhibitory substances are localized in the embryo but not in the endosperm or seed coat.

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