The use of leaf GPI and IDH isozymes to examine the origin of polyembryony in cultured ovules of seedless grape.

Isozyme analysis of young leaf tissue was performed on progeny produced from cultured ovules resulting from crosses of seedless × seedless grapes. Two polymorphic loci, Idh and Gpi-c, were found to segregate in a simple Mendelian fashion in the populations examined. Analyses of 70 seedlings indicated that most seedlings produced by this method were zygotic. 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.