Plants with 2 Y chromosomes suffer infertility, but not inviability, perhaps because XX individuals that produced male flowers had an advantage in establishing populations in the past. Or YY plants have abnormal gene dosage.
The Y chromosome of Mercurialis annua is homomorphic yet 1/3 is not recombining and is enriched in sex-biased genes, perhaps a sign of ongoing sexual antagonism.
Confirmation of male-specific PCR markers in the annual plant Mercurialis annua.
A study of viability and fertility of YY plants, produced by hormonal treatment and prunning, allows to determine the phenotypic effects of possible Y chromosome degeneration.
Fluorescent in-situ hybridisation in M. annua.