Seed sexing revealed female bias in two Rumex species

Sex-ratio bias in seeds of dioecious Rumex species with sex chromosomes is an interesting and still unsettled issue. To resolve gender among seeds of R. acetosa and R. thyrsiflorus (two species with an XX/XY 1 Y 2 sex chro mosome system), this work applied a PCR-based method involving DNA markers located on Y chromosomes. Both species showed female-biased primary sex ratios, with female bias greater in R. acetosa than in R. thyrsi florus . The observed predominance of female seeds is consistent with the view that the female biased sex ratios in Rumex are conditioned not only postzygotically but also prezygotically.