isozyme data of 11 plants from 5 polyembryonic ovules , along with data previously reported , suggest that several mechanisms may be operative in grape that give rise to polyembryony : 1 ) fertilization and development of more than one cell in the embryo sac , 2 ) adventive embryogenesis from the zygote , or 3 ) embryogenic development of gametic cells in addition to the zygote in the embryo sac .
C0015914
fertilization
C0678723
development