Abstract
Cocoa flowers have a limited period of longevity; more than 90% of unpollinated flowers abscised within 32 h after anthesis. Abscisic acid (ABA) levels increased significantly prior to abscission. By 21 h after anthesis, ABA levels had increased almost 10-fold, and by 32 h flowers had 20-fold higher levels of ABA than at anthesis. Fluridone completely inhibited both the increase in ABA, the formation of an abscission zone, and the abscission and senescence of flowers. In contrast, ethylene production increased only slightly 21 h after anthesis and was only 2-fold higher after 32 h. Aminoethoxyvinylglycine (AVG) delayed but did not prevent abscission. In cocoa flowers, ABA is the primary regulator of abscission; ethylene accelerates abscission but only in the presence of ABA. Naphthalene acetic acid (NAA) treatment of flowers at anthesis prevented abscission zone formation and flower abscission, but did not induce fruit set. All parts of the NAA-treated flower except the pedicel senesced after 6 days. NAA+AVG treatment only delayed, whereas fluridone treatment completely prevented flower senescence.
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References
Abeles FB (1969) Abscission: Role of cellulase. Plant Physiol 44: 447–452
Addicott FT (1982) Physiology. Berkeley CA: Abscission, UC Press, pp 97–152
Aneja M, Gianfagna T and Ng E (1996) Episodic growth and abscisic acid metabolism in cacao. Plant Growth Regul 20: 209–216
Baker RP, Hasenstein KH and Zavada MS (1997) Hormonal changes after compatible and incompatible pollination in Theobroma cacao L. HortSci 32: 1231–1234
Bentley B, Morgan CB, Morgan DC and Saad FA (1975) Plant growth substances and effects of photoperiod on flower bud development in Phaseolus vulgaris. Nature 256: 121–122
Beyer EM Jr (1975) Abscission: The initial effect of ethylene is in the leaf blade. Plant Physiol 55: 32–327
Davenport TL, Morgan PW and Jordan WR (1980) Reduction of auxin transport with age and internal water deficits in cotton petioles. Plant Physiol 65: 1023–1025
Davis LA and Addicott FT (1972) Abscisic acid: Correlations with abscission and with development in the cotton fruit. Plant Physiol 49: 644–648
Dunlap JR, Wang YT and Skaria A (1994) Abscisic acid-and ethylene-induced defoliation of Radermachera sinica L. Plant Growth Regul 14: 243–348
Jackson MB and Osborne DJ (1972) Abscisic acid, auxin and ethylene in explant abscission. J Exp Bot 23: 849–862
Jacobs WP (1958) Further studies on the relation between auxin and abscission of coleus leaves. Am J Bot 45: 673–675
Morgan PW (1984) Is ethylene the natural regulator of abscission? In: Fuchs Y and Chalutz E (eds) Ethylene-Biochemical, Physiological and Applied Aspects. The Netherlands: Martinus Nijhoff/Dr W. Junk, the Hague, pp 231–240
Osborne DJ (1991) Ethylene in leaf ontogeny and abscission. In: Mattoo AK and Suttle JC (eds) The Plant Hormone Ethylene. Boca Raton FL: CRC Press, pp 193–214
Porter NG (1976) The role of abscisic acid in flower abscission in Lupinus luteus. Physiol Plant 40: 50–54
Reid MS (1985) Ethylene abscission. HortSci 20: 45–50
Riov J, Dagan E, Goren R and Yang SF (1990) Characterization of abscisic acid-induced ethylene production in citrus leaf and tomato fruit tissues. Plant Physiol 92: 48–53
Sagee O, Goren R and Riov J (1980) Abscission of citrus leaf explants. Interrelationships of abscisic acid, ethylene, and hydrolytic enzymes. Plant Physiol 66: 750–753
Sargent JA, Osborne DJ and Dunford SM (1984) Cell separation and its hormonal control during fruit abscission in the gramineae. J Exp Bot 35: 1663–1674
Sexton RA (1995) Abscission. In: Pessarakli M (ed) Handbook of Plant and Crop Physiology, pp 497–527
Suttle JC and Hultstrand JF (1993) Involvement of abscisic acid in ethylene-induce cotyledon abscission in cotton seedlings. Plant Physiol 101: 641–645
Suttle JC and Abrams SR (1993) Abscission-promoting activities of abscisic acid and five abscisic acid analogs in cotton seedlings and explants. Plant Growth Regul 12: 111–117
Tucker ML, Sexton R, del Campillo E and Lewis LN (1988) Bean abscission cellulase: characterization of a cDNA clone and regulation of gene expression by ethylene and auxin. Plant Physiol 88: 1257–1262
Wien HC and Zhang Y (1991) Prevention of flower abscission in bell pepper. J Am Soc Hort Sci 116: 516–519
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Aneja, M., Gianfagna, T. & Ng, E. The roles of abscisic acid and ethylene in the abscission and senescence of cocoa flowers. Plant Growth Regulation 27, 149–155 (1999). https://doi.org/10.1023/A:1006153502897
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DOI: https://doi.org/10.1023/A:1006153502897