Annals of Botany

Genome size and seed mass in Aesculus

The genus Aesculus (horse chestnut, buckeye) consists of 12 to 19 extant species native to the temperate Northern Hemisphere. Aesculus is notable amongst woody angiosperms for its unusually large seeds. While chromosome counts are available for many Aesculus species, only one has had its genome size measured.

Two fruit/seed morphotypes, I (UCD Arboretum) - upper row and II (Quarry Hill Botanical Garden) - lower row, of Aesculus indica.
Two fruit/seed morphotypes, I (UCD Arboretum) – upper row and II (Quarry Hill Botanical Garden) – lower row, of Aesculus indica.

Krahulcová et al. provide chromosome numbers for three additional species and 2C nuclear DNA values for seven Aesculus species confirming the hypothesis that the genome size in this genus is surprisingly low, not only within its own family (Sapindaceae), but also within woody angiosperms. The genome sizes seem to be distinct and non-overlapping among the four major Aesculus clades. The correlation between the 2C values and seed masses in examined species is slightly negative and not significant. However, when the four major clades are treated separately, there is consistent positive association between larger genome size and larger seed mass within individual lineages.

Reference

Krahulcová, A., Trávníček, P., Krahulec, F., & Rejmánek, M. (2017). Small genomes and large seeds: chromosome numbers, genome size and seed mass in diploid Aesculus species (Sapindaceae). Annals of Botany, mcw261. https://doi.org/10.1093/aob/mcw261

About the author

Annals of Botany Office

The Annals of Botany Office is based at the University of Oxford.