Comparative karyotypes of three Philippine native orchids : Dendrobium amethystoglossum RCHB., Dendrobium heterocarpum Lindl., and Dendrobium secundum (Blume) Lindl.

Date

4-2005

Degree

Bachelor of Science in Biology

Major Course

Major in Ecology Genetics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Celia B. Dela Viña

Abstract

Chromosome characteristics based on mitotic behavior, size, arm ratio, relative length, and types according to centromere position were determined in three Philippine native orchids, namely Dendroblum amethystoglossum Rchb., D. heterocarpum Lindl., and D. secundum (Blume) Lindl. Normal mitotic stages were observed from the acetocarmine squash preparations of the root tip cells of the three species. Mitotic index was low at 21.4% in D. amethystoglossum. 19.64% in D. heterocarpum. and 24.30% in D. secundum. In the three species, the karyotypes revealed a diploid chromosome number of 2n = 38. The average relative lengths ranged from 0.0309 to 0.0765 for D. amethystoglossum, 0.0311 to 0.0853 for D. heterocarpum. and 0.0260 to 0.0715 for D. secundum. D. amethystoglo.ssum and D. secundum shared the same chromosome profiles; their karyotypes revealed three submetacentric chromosomes (chromosome pairs 3, 13 and 16 for D. amethystoglossunt and 6, 14, and 16 for D. secundum), one telocentric chromosome (chromosome pair 19), and the remaining 15 were all metacentric chromosomes. In D. heterocarpum, three chromosomes were submetacentric (chromosome pairs 10, 13, and 16), two were telocentric (chromosome pairs 18 and 19), one was subtelocentric (chromosome pair 12), and the remaining 13 were all metacentric.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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