Histochemical Changes in the Seed Coats Structure of Three Species of Abelmoschus (Medik.) Under Different Moisture Content Levels
Maria Lea H. Villavicensio*, Nestor C Altoveros and Teresita H. Borromeo1
National Plant Genetic Resouces Laboratory
Crop Science Cluster- Institute of Plant Breeding, College of Agriculture
University of the Philippines Los Baños, College, Laguna
The seed coat structures of 3 species of Abelmoschus were investigated through histochemistry and light microscopy to determine the nature and localization of chemical compounds present and explain the role of the different compounds on hardseededness and seed coat impermeability. Results showed the presence of lignins and phenols, both with hydrophobic characters, as proven by earlier work in the mesophyll layer of the hilar region and the palisade layer of the seed coats of A. esculentus, A. moschatus, and A. tetraphyllus var. pungens at 5%, 9%, and 13% moisture content. Tannins and lipids were found in the transition part of the palisade layer and in the mesophyll with amount increasing at low seed moisture content in the transition part of A. esculentus. The presence of these compounds may contribute to hardseededness and impermeability of the seed coat.
INTRODUCTION
The genus Abelmoschus belongs to the Family Malvaceae. This family has about 50 genera and 1,000 species of herbs, shrubs, and rarely small trees, with a world-wide distribution. Among the species in the genus, A. esculentus (syn. Hibiscus esculentus) is an annual vegetable crop, commonly known as "okra" or lady’s finger. The other wild species included in this study are A. moschatus and A. tetraphyllus, both found in the Philippines. The seeds of each species vary in shape, size, color, and surface texture.
REFERENCES
ANDERSON WH, CAROLUS RI, WATSON DP. 1953. The germination of okra seeds as influenced by treatment with acetone and alcohol. Proc. Am. Soc. Hortic. Sci. 62: 427-432.
BOESEWINKEL FD, BOUMAN F. 1995. The Seed: Structure and Function. In: Kigel, J. and G. Galili (eds.). Seed Development and Germination. 270 Madison Ave., New York, New York, USA: Marcel Dekker Inc. 853p.
CORNER EJH. 1976. The Seeds of Dicotyledons. Vol. 1. Great Britain: Cambridge University Press. 311p.
EGLEY GH, PAUL RN JR, LAX AR. 1986. Seed coat imposed dormancy: Histochemistry of the region controlling onset of water entry into Sida spinosa seeds. Physiol. Plant. 67: 320-327.
ELLIS RH, HONG TD, ROBERTS EH. 1985. Handbook of Seed Technology for Genebanks. Vol. II. Compedium of specific germination information and test recommendations. IBPGR, Rome. 667p.
FEDER N, O’BRIEN TP. 1968. Plant microtechnique: Some principles and new methods. Am. J. Bot. 55(1): 123-142.
HARRIS WM. 1987. Comparative ultrastructure of developing seed coats of “hard-seeded” and “softseeded” varieties of soybean, Glycine max (L.) Merr. Bot. Gaz. 148(3): 324-331.
HONG TD, LININGTON S, ELLIS RH. 1996. Seed Storage Behaviour: A Compendium. Handbooks for Genebanks No. 4. Rome: International Plant Genetic Resources Institute.
JENSEN WA. 1962. Botanical Histochemistry. Principles and Practices. USA: W. H. Freeman & Co. 408p.
JOHANSEN DA. 1940. Plant Microtechnique. USA: McGraw-Hill Book Co. Inc. 523p.
MARBACH I, MAYER AM. 1974. Permeability of seed coats to water as related to drying conditions and metabolism of phenolics. Plant Physiol. 54: 817-820.
SERRATO-VALENTI G, CORNARA L, LOTITO S, QUAGLIOTTI L. 1992. Seed coat structure and histochemistry of Abelmoschus esculentus. Chalazal region and water entry. Annu. Bot. 69: 313-321.
SERRATO-VALENTI G, MELONE L, FERRO M, BOZZINI A. 1989. Comparative studies on testa structure of hardseeded and softseeded varieties of Lupinus angustifolius. Seed Sci. & Technol. 17: 563-581.
SERRATO-VALENTI G, FERRO M, MODENESI P. 1990. Structural and histochemical changes in palisade cells of prosopis juliflora seed coat in relation to its water permeability. Annals of Bot. 65: 529-532.
VILLAVICENCIO ML H, MABESA RC. 2002. Anatomical changes in the seed coat structures of three Abelmoschus species (Moench.) at different moisture content levels. Philipp Agric Scientist. 85(1): 6-14.
WERKER E, MARBACH I, MAYER AM. 1979. Relation between the anatomy of the testa, water permeability and the presence of phenolics in the genus Pisum Ann Bot. 43: 765-771.
