Genome size and base composition of Bromeliaceae species assessed by flow cytometry

Abstract

Flow cytometry (FCM) has been used to estimate the nuclear DNA content of Bromeliaceae species, which constitutes relevant information for studies of taxonomy, evolution, genetic diversity, and reproductive biology in bromeliads. Nevertheless, C values have only been estimated for 58 out of the 3,140 existing Bromeliaceae species. Aiming to contribute to the genome database of Bromeliaceae, the current study was carried out to measure the nuclear DNA content and base composition of Bromelioideae and Tillandsioideae species occurring in the Atlantic Rainforest. The most adequate FCM procedure provided histograms exhibiting G0/G1 peaks with coefficients of variation below 5%, so that these histograms were used to measure the mean 2C and AT% values for all collected Bromelioideae and Tillandsioideae species. These values were statistically compared, and dendrograms were plotted. A second comparison was performed among all mean 2C values reported for Pitcairnioideae, Tillandsioideae, and Bromelioideae species. In accordance with previous statistical comparisons, two groups were formed: cluster 1, composed by Tillandsia loliacea, Tillandsia usneoides, and Tillandsia cyanea, and cluster 2, gathering other 69 species. Based on these results, we concluded that FCM was a rapid, accurate, and reliable technique to assess genome size and base composition. Furthermore, the FCM data reported here will contribute to the Monocot and Bromeliaceae database, which still displays several ongoing gaps, especially for endemic species.