Cytogenetics of the rare and endangered Trigonobalanus doichangensis (Fagaceae) from Northern Thailand

Anamthawat-Jónsson K., . and Chokchaichamnankit P., . Cytogenetics of the rare and endangered Trigonobalanus doichangensis (Fagaceae) from Northern Thailand. pp. 60-68. ISSN 0128-1283

Trigonobalanus doichangensis is rare and endangered in Thailand. The species is found in northern Thailand in hill-evergreen forests at high elevations. In this study T. doichangensis was identified for the first time from Khun Mae Kuong Forest in Chiang Mai Province and this discovery has extended the species distribution eastwards significantly. Samples were collected from trees of this species: twigs with fully grown leaves fruits and flowers were used for taxonomic identification whereas shoot and flower buds were used in the chromosome preparation. Results confirmed that T. doichangensis was diploid with chromosome number 2n 2x 14 (base number x 7 confirmed with meiosis) whereas other Fagaceae species from the same forest (Castanopsis Lithocarpus and Quercus) were diploid with 2n 2x 24. The karyotype analysis indicated a common genomic origin. The chromosomal mapping of highly repetitive 18S“25S and 5S ribosomal genes was performed by fluorescence in-situ hybridisation. Trigonobalanus doichangensis showed two pairs of 18S“25S rRNA loci (subtelomeric and paracentromeric) and one pair of 5S paracentromeric rRNA loci. The presence of linked 5S and 18S“25S ribosomal sites indicated an ancestral state of the genome of T. doichangensis.

Full text available from: Official URL: http://www.frim.gov.my/v1/JTFSOnline/jtfs/v27n1/06...

Abstract

Trigonobalanus doichangensis is rare and endangered in Thailand. The species is found in northern Thailand in hill-evergreen forests at high elevations. In this study T. doichangensis was identified for the first time from Khun Mae Kuong Forest in Chiang Mai Province and this discovery has extended the species distribution eastwards significantly. Samples were collected from trees of this species: twigs with fully grown leaves fruits and flowers were used for taxonomic identification whereas shoot and flower buds were used in the chromosome preparation. Results confirmed that T. doichangensis was diploid with chromosome number 2n 2x 14 (base number x 7 confirmed with meiosis) whereas other Fagaceae species from the same forest (Castanopsis Lithocarpus and Quercus) were diploid with 2n 2x 24. The karyotype analysis indicated a common genomic origin. The chromosomal mapping of highly repetitive 18S“25S and 5S ribosomal genes was performed by fluorescence in-situ hybridisation. Trigonobalanus doichangensis showed two pairs of 18S“25S rRNA loci (subtelomeric and paracentromeric) and one pair of 5S paracentromeric rRNA loci. The presence of linked 5S and 18S“25S ribosomal sites indicated an ancestral state of the genome of T. doichangensis.

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Item Type:	Article
AGROVOC Term:	Chromosomes
AGROVOC Term:	Karyotypes
AGROVOC Term:	Ribosomes
AGROVOC Term:	Fagaceae
AGROVOC Term:	Cytogenetics
AGROVOC Term:	genomics
AGROVOC Term:	Genetic diversity within species
AGROVOC Term:	Gene mapping
AGROVOC Term:	Castanopsis
AGROVOC Term:	Quercus
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 06:27
URI:	http://webagris.upm.edu.my/id/eprint/21444

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