Figure 3.

Different routes giving rise to polyploid plants. The formation of polyploids can occur via the formation of unreduced male and female gametes, leading to the formation of triploid seeds that when overcoming the triploid block give rise to triploid plants. Triploids can also arise in consequence of polyspermy, which, if only the egg cell is fertilized by two sperm cells, will give rise to a viable triploid seed with a balanced triploid endosperm and a triploid embryo. Triploids can give rise to swarms of gametes with different grades of ploidy and thus act as a bridge to the formation of stable polyploids. m, maternal; p, paternal.