Cytology

Cytotaxonomic research on Gesneriaceae started in the 1920s. Since then, around 1000 counts on members of the family have been published. At RBGE, cytology of the family has been pursued since the early 1960s. Living plants are ideal for cytotaxonomic work, as chromosomes can best be studied in roots or buds taken from actively growing plants.

FISH images showing 45S rnDNA sites in Streptocarpus johannis (top) and Aeschynanthus nummularius (bottom)
Aeschynanthus and Streptocarpus are the most intensively studied cytologically at present and our karyotype research has given interesting insight into the chromosome evolution within these genera: Streptocarpus species are very conservative and show little changes in chromosome numbers, while in Aeschynanthus chromosome evolution involved several changes in basic chromosome numbers. Fluorescent in-situ hybridisation (FISH) techniques are used to investigate the number and position of chromosome markers, such as ribosomal DNA sites in nucleolar organiser regions (NORs). Mapping these markers onto robust phylogenies allows us to investigate genome evolution in the absence of variation in chromosome numbers, such as within the subgenera of Streptocarpus.

A searchable cytology website ‘WebCyte' has been developed, summarising all published and unpublished chromosome investigations in Gesneriaceae. This database allows interactive searches for existing counts, as well as access to statistics of species or genus coverage.

Selected References:

MÖLLER M, G Kokubugata, K Jong (2008). Aspects of genome evolution in Gesneriaceae: patterns of 45S-nrDNA site evolution based on evidence from fluorescent in-situ hybridization (FISH). International Journal of Plant Sciences 169(5): 667-676. 

Denduangboripant, J., Cronk, Q.C.B., Kokubugata, G., & Möller, M. (2007). Variation and inheritance of nuclear ribosomal DNA clusters in Streptocarpus (Gesneriaceae) and their biological and phylogenetic implications. International Journal of Plant Sciences 168(4):455-467.

Möller, M. & Kiehn, M. (2004). A synopsis of cytological studies in Gesneriaceae. Edinburgh Journal of Botany 60(3):425-447.

Rashid, M.H., Jong, K. & Mendum, M. (2001). Cytotaxonomic observations in the genus Aeschynanthus (Gesneriaceae). Edinburgh Journal of Botany 58(1): 31-43.

Zhou, P., Gu, Z.-J. & Möller, M. (2004). New chromosome counts and nuclear characteristics for some members of Gesneriaceae subfamily Cyrtandroideae from China and Vietnam. Edinburgh Journal of Botany60(3):449-466.

Contact: 

Michael Möller 

Kwiton Jong 

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