Modulations in seed micromorphology reveal signature of adaptive species-diversification in Dendrobium (Orchidaceae)

Bhupendra  Chaudhary; Pritam  Chattopadhyay; Nirmalya  Banerjee

doi:10.4236/oje.2014.42005

Bhupendra Chaudhary^*, Pritam Chattopadhyay, Nirmalya Banerjee

Abstract: During speciation in flowering plants, many morphological characters were evolved in response to continuous selection pressure. Such characters are largely governed by genetic changes or get modulated according to ecological adaptations. To explore the potential of latter, a novel comparative analysis of seed micromorphology and ultrastructure was performed in twenty species in the genus Dendrobium (Orchidaceae) from well-defined altitude based phytogeographical realms i.e. temperate, subtropical and tropical regions. Seed morphological characteristics from all collected species were examined using 13 quantitative traits descriptors. Comparative seed morphology revealed that the species from temperate region have larger seed volumes and seed volume/embryo volume ratio than species from subtropical or tropical regions irrespective of their phylogenetic association. Hence, phylogenetically related species emphasized their preference for a climatic region as their prime habitat. Similar trends towards gradual increase of percentage free air space were observed in the species of tropical to subtropical and subtropical to temperate regions. The higher percentage of free air space may have an advantage for the species from temperate region with relatively low atmospheric pressure that had greater buoyancy for optimal seed dispersal. Also, phylogenetically distant species from a particular climatic region, showed characteristic features of the testa cell walls sculptured with bead-like orna-mentations or covered with cottony white substances. Based on these observations, it may be concluded that seed volume, % free air space and seed coat ornamentation in Dendrobium species are signatures of adaptation according to climatic preferences rather than their selection during speciation.

Keywords: Dendrobium; Seed Micromorphology; Phytogeography; Tropical; Subtropical; Temperate; Phylogeny

Cite this paper: Chaudhary, B. , Chattopadhyay, P. and Banerjee, N. (2014) Modulations in seed micromorphology reveal signature of adaptive species-diversification in Dendrobium (Orchidaceae). Open Journal of Ecology, 4, 33-42. doi: 10.4236/oje.2014.42005.

References

[1] [1] Ohno, S. (1970). Evolution by gene duplication. Springer-Verlag, New York.
http://dx.doi.org/10.1007/978-3-642-86659-3

[2] Chase, M.W., Cameron, K.M., Barrett, R.L. and Freudenstein, J.V. (2003) DNA data and Orchidaceae systematics: A new phylogenetic classification. In: Dixon, K. M., Kell, S.P., Barrett, R.L. and Cribb, P.J., Eds., Orchid Conservation, Natural History Publications, Kota Kinabalu, 69-89.

[3] Clements, M. (2003). Molecular phylogenetic systematics of the Dendrobiinae (Orchidaceae), with emphasis on Dendrobium sect. Pedilonum. Telopea, 10, 247-298.

[4] Kamemoto, H., Amore, T. and Kuehnle, A. (1990) Breeding Dendrobium orchids in Hawaii. University of Hawaii Press, Honolulu.

[5] Kjellson, G., Rasmussen, F. and Du Puy, D. (1985) Pollination of Dendrobium infundibulum, Cymbidium insigne (Orchidaceae) and Rhododendron lyi (Ericaceae) by Bombus eximius (Apidae) in Thailand: A possible case of floral mimicry. Journal of Tropical Ecology, 1, 289-302.
http://dx.doi.org/10.1017/S0266467400000389

[6] Yukawa, T., Ohba, H., Cameron, K. and Chase, M. (1996) Chloroplast DNA phylogeny of subtribe Dendrobiinae (Orchidaceae): Insights from a combined analysis based on rbcL sequences and restriction site variation. Journal of Plant Research, 109, 169-176.
http://dx.doi.org/10.1007/BF02344542

[7] Leitch, I., Kahandawala, I., Suda, J., Hanson, L., Ingrouille, M., Chase, M. and Fay, M. (2009) Genome size diversity in orchids: Consequences and evolution. Annals of Botany, 104, 469-481.
http://dx.doi.org/10.1093/aob/mcp003

[8] Baker, M. and Baker, C. (1996) Orchid Species Culture: Dendrobium. Timber Press Inc., Portland.

[9] Chase, M. (1999) Molecular systematics, parsimony, and orchid classification. In: Pridgeon, A.M., Cribb, P.J., Chase, M.W. and Rasmussen, F.N., Eds., Genera Orchidacearum, General Introduction, Apostasioideae, Cypripedioideae, Oxford University Press, Oxford, 81-88.

[10] Chattopadhyay, P., Banerjee, N. and Chaudhary, B. (2010) Precise seed micromorphometric markers as a tool for comparative phylogeny of Dendrobium (Orchidaceae). Floriculture and Ornamental Biotechnology, 4, 36-44.

[11] Dressler, R. (1993) Phylogeny and classification of the orchid family. Dioscorides Press, Portland.

[12] Hooker, J. (1890) Dendrobium. Flora of British India, 5, 710-752 (suplements, additions, and corrections).

[13] Rasmussen, F. (1999) The development of orchid classification. In: Pridgeon, A.M., Cribb, P.J., Chase, M.W. and Rasmussen, F.N., Eds., Genera Orchidacearum, General Introduction, Apostasioideae, Cypripedioideae, Oxford University Press, Oxford, 3-12.

[14] Wood, H. (2006) The Dendrobiums, A.R.G. Ganter Verlag, Ruggell/Liechtenstein.

[15] Clements, M. (1999) Embryology. In: Pridgeon, A.M., Cribb, P.J., Chase, M.W. and Rasmussen, F.N. Eds., Genera Orchidacearum, Genera Orchidacearum, General Introduction, Apostasioideae, Cypripedioideae, Oxford University Press, Oxford, 38-55.

[16] Molvary, M. and Chase, M. (1999) Seed morphology. In: Pridgeon, A.M., Cribb, P.J., Chase, M.W. and Rasmussen, F.N., Eds., Genera Orchidacearum, Genera Orchidacearum, General Introduction, Apostasioideae, Cypripedioideae, Oxford University Press, Oxford, 59-66.

[17] Molvray, M. and Kores, P. (1995) Character analysis of the seed coat in Spiranthoideae and Orchidoideae, with special reference to the Diurideae (Orchidaceae). American Journal of Botany, 82, 1443-1454.
http://dx.doi.org/10.2307/2445872

[18] Vij, S., Kaur, P., Kaur, S. and Kaushal, P. (1992) The orchid seeds: Taxonomic, evolutionary and functional aspects. Journal of Orchid Society of India, 6, 91-107.

[19] Arditti, J., Michaud, J. and Healey, P. (1979). Morphometry of orchid seeds. I. Paphiopedilum and native California and related species of Cypripedium. American Journal of Botany, 66, 1128-1137.
http://dx.doi.org/10.2307/2442211

[20] Arditti, J., Michaud, J. and Healey, P. (1980) Morphometry of orchid seeds. II. Native California and related species of Calypso, Cephalanthera, Corallorhiza and Epipactis. American Journal of Botany, 67, 347-360.
http://dx.doi.org/10.2307/2442345

[21] Swamy, K., Kumar, H., Ramakrishna, T. and Ramaswamy, S. (2004) Studies on seed morphometry of epiphytic orchids from Western Ghats of Karnataka. Taiwania, 4, 124140.

[22] Larry, H. (1995) Seed morphology of Hydrangeaceae and its phylogenetic implications. International Journal of Plant Science, 156, 555-580.
http://dx.doi.org/10.1086/297279

[23] Mathews, J. and Levins, P. (1986) The systematic significance of seed morphology in Portulaca (Portulacaceae) under scanning electron microscopy. Systematic Botany, 11, 302-308. http://dx.doi.org/10.2307/2419120

[24] Ness, B. (1989) Seed morphology and taxonomic relationships in Calochotus (Liliaceae). Systematic Botany, 14, 495-505. http://dx.doi.org/10.2307/2418993

[25] Jeeja, G. and Ansari, R. (1994). Taxonomic significance of seed surface morphology in Orchidaceae. Indian Association of Angiospermic Taxonomy, 4, 48-59.

[26] John, R. and Jack, K. (1998) Orchids. 3rd Edition, Sunset Books, Sunset Publishing Corp., Menlo Park, 11-101.

[27] Lumga, M., Cozzolino, S. and Kocyan, A. (2006) Exine micromorphology of Orchidinae (Orchidoideae, Orchidaceae): Phylogenetic constrain or ecological influence? Annals of Botany, 98, 237-244.
http://dx.doi.org/10.2307/2418993

[28] Pradhan, U. (1979) Indian orchids: Guide to identification and culture. Vol. 2, Pradhan, Kalimpong.

[29] Harris, J. and Harris, M. (2001) Plant Identification terminology: An illustrated glossary. Spring Lake Publication, Payson.

[30] Bose, S., Bhattacharjee, S., Das, P. and Basak, U. (1999) Orchids of India. Naya Prokash, Calcutta.

[31] Chowdhery, H. (1998) Orchid flora of Arunachal Pradesh. Bisen Singh Mahendra Pal Singh, Dehradun

[32] Pearce, N. and Cribb, P. (2002). The orchids of Bhutan. Royal Botanic Gardens and Royal Government of Bhutan, Edinburgh

[33] Roberts, J., Allman, L., Bealr, C., Butter, R., Crook, K. and McGough, H. (1997). CITES Orchid checklist. Royal Botanic Gardens, Kew England.