Changes in Abscission‐accelerating Substances With Development of Cotton Fruit

Abscisic acid was measured in developing cotton fruit (Gossypiuln hirsutunt) by means of gas-liquid chromatography.High levels of abscisic acid occurred in correlation with abortion and abscission of young fruit, with low germination of immature seed, and with senescence and dehiscence of mature fruit. Declining or low levels of abscisic acid occurred in correlation with the period of most rapid fruit growth and with high germination of immature and mature seed. Abscisic acid was isolated and identified from the young fruit of cotton (12,13) and was demonstrated to be an abscission-accelerating hormone of young cotton fruit (3). It occurs in the fruits of a wide variety of plants (see 4, 10); however, knowledge of the occurrence of ABA in correlation with the development and/or abscission of fruits is still quite limited. Van Steveninck (22) found that the occurrence of an inhibitor, now known to be ABA (14), was correlated with the abscission of young lupin fruit. Rudnicki and colleagues found ABA to increase with ripening of strawberry fruits (16) and of pears (17) and during the development of apple fruits (18).In bioassays for ABA the interference of other hormones has been a serious hazard. However, the recent development of chemical assays with a high degree of specificity (6, 8) enables measurement of ABA independently of the other hormones. The research reported in this paper was undertaken with two objectives: (a) to confirm and extend with quantitative data the occurrence of ABA in correlation with young fruit abscission in cotton, and (b) to obtain similar data over the entire life-span of the cotton fruit and correlate that information with the events that take place in the course of the development and maturation of seed, fiber, and walls of the cotton fruit. MATERIALS AND METHODSThe cotton used in these experiments was Gossypium hirsutum L., cultivars Acala 4-42 and Acala SJ-1, grown at the 'Present address: Alina Farms Corporation, McFarland, California 93250.United States Cotton Research Station, Shafter, California, in the summer of 1967. The plants were grown in rows 101.6 cm (40 inches) apart and thinned to one plant every 30.4 cm (12 inches). The cultural practices of irrigation and cultivation were the standard ones of the Station. Flowers at anthesis were tagged on two dates: 6 July (early) and 8 August (late). Only one flower per plant was tagged. On the early date the tagged flowers were either the first or second on the plant; on the late date the plants had numerous flower buds, flowers, and fruits in various stages of development. Fruits were collected at anthesis (day 0) and at 2. 4,6,8,10,15,20, 30, 40, and 50 days after anthesis.Collected fruits were frozen on solid CO2 and stored at -20 C until 5 min before extraction. Fifteen fruits 0 and 2 days old, 10 fruits 4, 6. and 8 days old, and five fruits each in the samples of 10 days and older were extracted. Before extraction bracts and pedicels were removed from the fruits, and fruits 15 days and older were separated into (a) ...

show abstract

“…Fruits were collected at anthesis (day 0) and at 2. 4,6,8,10,15,20,30,40, and 50 days after anthesis.…”

Section: Methodsmentioning

confidence: 99%

“…Fruits were collected at anthesis (day 0) and at 2. 4,6,8,10,15,20, 30, 40, and 50 days after anthesis.Collected fruits were frozen on solid CO2 and stored at -20 C until 5 min before extraction. Fifteen fruits 0 and 2 days old, 10 fruits 4, 6. and 8 days old, and five fruits each in the samples of 10 days and older were extracted.…”

mentioning

confidence: 99%

Abscisic Acid: Correlations with Abscission and with Development in the Cotton Fruit

Davis

Addicott

1972

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…The rate of movement was the same through the abscission zone as through petiole tissue. Patterns of accumulation and metabolic products are discussed.Abscisic acid has been shown to be a very effective abscissionpromoting agent in the cotton explant bioassay (1,2,13,14). It has been presumed that abscisic acid is rapidly transported in the explant to the abscission zone, its site of action (1), but to date no direct proof of this phenomenon has been offered.…”

mentioning

confidence: 99%

Movement of (RS)-Abscisic Acid in the Cotton Explant

Ingersoll

Smith

1970

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

The movement of abscisic acid in the cotton explant was investigated by bioassay and radioisotope techniques. The rate of movement was 20 to 30 millimeters per hour with most of the abscisic acid moving unchanged through the explant into the basal agar. The rate of movement was the same through the abscission zone as through petiole tissue. Patterns of accumulation and metabolic products are discussed.Abscisic acid has been shown to be a very effective abscissionpromoting agent in the cotton explant bioassay (1,2,13,14). It has been presumed that abscisic acid is rapidly transported in the explant to the abscission zone, its site of action (1), but to date no direct proof of this phenomenon has been offered. An alternative possibility is that abscisic acid is immobile and that it induces the production of an abscission-promoting agent or stimulus which is transported. A study of the movement of ABA in the explant was undertaken to answer the questions (a) does ABA move from the site of application to the abscission zone, (b) what is the rate of movement, (c) does it accumulate in any area of the explant? MATERIAIS AND METHODS All experiments were conducted with cotton explants excised from 14-day-old seedlings of Gossypium hirsutwn L. Acala SJ-1 grown in vermiculite subirrigated with tap water. The seedlings were grown in a growth chamber at 32 i 3 C with a 16-hr photoperiod of 5.8 X 104 erg/cm2.sec provided by cool white fluorescent lamps supplemented by incandescent bulbs.Explants from the cotyledonary nodes were cut with hypocotyl segments 9 mm long and epicotyl and petiole stumps 5 mm long. The cotton explant bioassay method of Addicott et al. (1) was employed except where noted. Briefly, the bioassay involved placing 10 explants (each containing two abscission zones) in a covered Petri dish. The bases of the explants were pushed into a 5-mm layer of 1.5% agar. The cut surfaces of the epicotyl and petioles were then treated with 5-,ul droplets of agar (0.75%) delivered by a 500-,l hypodermic syringe. Abscission was tested for by applying a momentary force equivalent to 5 g to the distal end of the petiolar stumps. Each treatment represented two dishes of 10 explants, and the experiments were repeated three times.The movement of ABA was studied with 2-l4C-abscisic acid produced according to the technique reported by Roberts et al. (11). After treatment the explants were cut into various sections as indicated in Figure 3. The pooled tissue sections were soaked for 24 hr in sealed vials in 2 ml of 95% ethanol made to 0.05 N with acetic acid to leach out labeled compounds. Fifteen milliliters of scintillation fluid (100 g of napthalene; 5 g of PPO [2,5-diphenyloxazole]; 1 liter of 1,4-dioxane) were added to the ethanol solutions in each vial containing the tissue sections. The 14C activity was determined by counting for 20 min per sample in a Beckman liquid scintillation spectrometer model 100.Recovery of the '4C-labeled compounds from the tissue and the basal agar was done by extracting with 80% metha...

show abstract

“…Many research workers have attempted to identify and measure hormone levels in cotton plants by using various bioassays (1,6,7,9,24,25,28). Because plant hormones are present in microgram quantities, the usefulness of bioassays has been limited because of interference of excessive quantities of impurities in extracts containing the hormones (2,14).…”

Section: Introductionmentioning

confidence: 99%

“…A single extract contained abscisic acid, indoleacetic acid, and gibberellins A1, A3, A4. A7, A9, and A13 in the first fraction; ethyl indole-3-acetate and indole-3-aldehyde in the second fraction; and the cytokinins 6-(3-methyl-4-hydroxybutylamino)purine (dihydrozeatin), 6-(4-hydroxy-3-methyl-2-trans-butenylamino) purine (zeatin), 6-(3-methyl-2-butenylamino)purine (2iP), 6-(3-methyl-2-butenylamino) .9 -A -D -ribofuranosylpurine (2iPA), and 6-(4-hydroxy-3-methyl-2-trans-butenylamino) -9-/3-D-ribofuranosylpurine (zeatin riboside) in the third fraction.Many research workers have attempted to identify and measure hormone levels in cotton plants by using various bioassays (1,6,7,9,24,25,28). Because plant hormones are present in microgram quantities, the usefulness of bioassays has been limited because of interference of excessive quantities of impurities in extracts containing the hormones (2,14).…”

mentioning

confidence: 99%

Identification of Plant Hormones from Cotton Ovules

Shindy

Smith²

1975

Plant Physiol.

162

View full text Add to dashboard Cite

An extract from 8-day-old cotton ovules (Gossypiumii hirsutuint L.) was partitioned into three fractions and each fraction was derivatized and analyzed separately. Gas-liquid chromatography and computer-controlled gas-liquid chromatography-mass spectrometry were used to separate, measure, and identify the naturally occurring plant hormones. A single extract contained abscisic acid, indoleacetic acid, and gibberellins A1, A3, A4. A7, A9, and A13 in the first fraction; ethyl indole-3-acetate and indole-3-aldehyde in the second fraction; and the cytokinins 6-(3-methyl-4-hydroxybutylamino)purine (dihydrozeatin), 6-(4-hydroxy-3-methyl-2-trans-butenylamino) purine (zeatin), 6-(3-methyl-2-butenylamino)purine (2iP), 6-(3-methyl-2-butenylamino) .9 -A -D -ribofuranosylpurine (2iPA), and 6-(4-hydroxy-3-methyl-2-trans-butenylamino) -9-/3-D-ribofuranosylpurine (zeatin riboside) in the third fraction.Many research workers have attempted to identify and measure hormone levels in cotton plants by using various bioassays (1,6,7,9,24,25,28). Because plant hormones are present in microgram quantities, the usefulness of bioassays has been limited because of interference of excessive quantities of impurities in extracts containing the hormones (2,14).Recently, development of GLC has provided a physicalchemical assay of ABA (11,19), auxins (13,29), cytokinins (30), and gibberellins (8), demonstrating the feasibility of qualitative as well as quantitative measurements of naturally occurring plant hormones. Gas-liquid chromatography-mass spectrometry has been used for further identification of some of these hormones (15,21,22,31).Computer-controlled GLC-MS4 has been used for identifica- 6-(4-hydroxy-3-methyl-2-trans-butenylamino)purine; dihydrozeatin: 6-(3-methyl-4-hydroxybutylamino)purine; zeatin riboside: 6-(4-hydroxy-3-methyl-2-trans-butenylamino)-9-PB-D-ribofuranosylpurine; 2iP: 6-(3-methyl-2-butenylamino)purine; 2iPA: 6-(3-methyl-2-butenylamino)-9-fl-D-ribofuranosylpurine: 3iPA: 6-(3-methyl-3-butenylamino)-9-I3-D-ribofuranosylpurine.tion of cytokinins (31), gibberellins, and ABA (21). Abscisic acid (11) and IAA (32) have been identified from cotton tissues by GLC but we have found no report in which ABA, gibberellins, cytokinins, and auxins were measured in a single extract by physical-chemical assays.The objective of this investigation was to utilize GLC and computer-controlled GLC-MS to separate, identify, and measure individual plant hormones of four major groups from a single extract of ovules from 8-day-old cotton fruit. MATERIALS AND METHODSCotton plants (Gossypiu,n hirsutum L., cv. Acala SJ-1) were grown in a greenhouse. Cotton flowers were tagged at anthesis and bolls were harvested 8 days thereafter. The developing ovules were separated from the fruits, frozen immediately on Dry Ice, and stored at -20 C until the time of extraction. Extraction Procedure. In different experiments, 2 to 5 g of frozen ovules were ground in cold 80% (v/v) aqueous methanol with a mortar and pestle. The macerate was transferred to a fla...

show abstract

Changes in Abscission‐accelerating Substances With Development of Cotton Fruit

Cited by 8 publications

References 13 publications

Abscisic Acid: Correlations with Abscission and with Development in the Cotton Fruit

Abscisic Acid: Correlations with Abscission and with Development in the Cotton Fruit

Movement of (RS)-Abscisic Acid in the Cotton Explant

Identification of Plant Hormones from Cotton Ovules

Contact Info

Product

Resources

About