Abstract
Background: Dipterocarpaceae is a pantropical tree family that plays an important role in our understanding of the ecology of Asian tropical rain forests. However, genome sizes for members of the Dipterocarpaceae are still poorly known.
Aims: To report the genome size of 115 dipterocarp species and examine the variation and evolution of genome size in this family.
Methods: Genome size was estimated using flow cytometry. Both the rpoB and trnL intron were sequenced to uncover the evolution of genome size within a phylogenetic framework.
Results: The 1C genome size varied between 0.267 and 0.705 pg in Shorea hemsleyana and Shorea ovalis, respectively, a 2.64-fold variation across the family. Most dipterocarps are characterised by very small genomes with a mean 1C value of 0.416 pg (sd = 0.075) and five polyploids are recorded. The ancestral genome size for dipterocarps was reconstructed as 1Cx = 0.481 pg (95% CI = 0.433–0.534).
Conclusions: Genome size variation in dipterocarps was characterised by very small values with a narrow range. Overall, genome size reduction from the ancestral state is a general trend in Dipterocarpaceae.
Acknowledgements
We thank Ghazali Jaafar, Yahya Marhani, Ramli Ponyoh, Mariam Din, Sharifah Talib and Suryani Che Seman for their assistance both in the field and laboratory. Phoon Lee Quen and Cheang Pek Tan provided technical support in operating the FACSCalibur flow cytometer. We are also grateful to Ilia Leitch, Spencer Johnston, Jaroslav Dolezel, Jan Suda, Deepak Ohri, Chris Venditti and anonymous reviewers for their helpful discussion and comments. The seeds of Glycine max were supplied by Jaroslav Dolezel. This work was supported by Forest Research Institute Malaysia: [grant number 40300402006], [grant number 40310502013].
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No potential conflict of interest was reported by the authors.
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Notes on contributors
Chin Hong Ng
Chin Hong Ng conducts research on plant genome size, plant DNA profiling and population genetics.
Soon Leong Lee
Soon Leong Lee is involved in research on ecological genetics of plant species, plant genomic and transcriptomic, and plant DNA profiling and barcoding.
Lee Hong Tnah
Lee Hong Tnah conducts research on plant phylogeography and evolution, plant DNA profiling and barcoding, and development of microsatellite markers.
Kevin Kit Siong Ng
Kevin Kit Siong Ng is involved in plant genomics, ecological and conservation genetics of plant species, plant DNA profiling and barcoding.
Chai Ting Lee
Chai Ting Lee conducts research on forest genetics, namely development of microsatellite markers in tropical plant species and conservation genetics of important timber species.
Maria Madon
Maria Madon is a senior scientist. She conducts molecular cytogenetic studies of the oil palm and is involved in plant breeding efforts to improve oil palm planting material.