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

Abstract

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) ...

Transcriptome Analysis of Ten-DPA Fiber in an Upland Cotton (<i>Gossypium hirsutum</i>) Line with Improved Fiber Traits from Phytochrome A1 RNAi Plants

“…Therefore, the active level of ABA might be increased by decreasing the expression of ABA 8'-hydroxylase in the RNAi line. These results are consistent with the physiology data that ABA concentrations increased from the day of anthesis to 10 DPA and then declined until 20 DPA [47]. The fiber development is a dynamic process; at the stage of 10 DPA, ABA inhibits fiber cell initiation and fiber cells are predominantly elongated in RNAi cotton.…”

Increase in Free and Bound Abscisic Acid during Natural and Ethylene-induced Senescence of Citrus Fruit Peel

“…Using bioassay of crude extracts, we have shown previously that ABA-like growth inhibitors increase rapidly in citrus fruit peel after harvest (5). Similar accumulation of ABA and ABA-like components was reported for other fruits (3,20,21) and for leaf tissues approaching senescence (2,12).…”

Endogenous Ethylene and Abscisic Acid Relative to Phytogerontology

“…Davis and Addicott (21) reported similar increases of ABA at i response would dictate that ethylene concentrations the time of young cotton plant abscission. r below threshold levels for a long period of time would…”