The presence of three full sets of
chromosomes in the
nuclear material of a
cell. This occurs during the
pollination of plants, in which one of the three male
gametes which passes into the plant fuses with the two
polar bodies in the
ovum of the other plant, forming one triploid cell from three
haploid ones. This later forms the food store which is part of the
seed. This is called Double Fertilization, as the fusing of these gametes occurs
parallel to the fusing of the male and female gametes to form the
diploid zygote.
An
animal with triploid DNA could form through a fault in either
meiosis or during the
development of the zygote, although this individual would most likely be
aborted, die very soon after being born, be badly disabled or be unable to
reproduce.