Evaluation of polysomaty and estimation of genome size in Polygala vayredae and P. calcarea using flow cytometry

In seed plants, endopolyploidy is regarded as a common and developmentally regulated phenomenon. However, in Polygalaceae polysomaty has never been studied. In this work the endopolyploidy of Polygala vayredae (2n = 28, subgenus Chamaebuxus) and P. calcarea (2n = 34, subgenus Polygala) was evaluated using flow cytometry. With this technique it was possible to observe polysomaty in endosperm, leaves and petals of both species, although with different patterns. Usually, in P. vayredae, 2C and 4C ploidy levels were detected while for leaves of P. calcarea, an extra 8C level was observed. In P. vayredae, statistically significant differences were observed in the endopolyploid level between fully expanded young leaves and 1-year-old mature leaves. Nuclear DNA content analysis in these taxa revealed significant differences, with P. vayredae presenting a higher genome size (2C = 2.71 pg DNA) than P. calcarea (2C = 0.98 pg DNA). These data and the highest level of polysomaty found in P. calcarea seem to point to a negative correlation between genome size and endopolyploidy, as observed in other works.