Fertilization and embryo development in the genus Lupinus/Tourn. II. Fertilization and embryo development following reciprocal, species hybridization

Jaranowski, J.

Genet Polon 3(3): 333-368


Accession: 024688817

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Lupinus albus, L. angustifolius and L. luteus carry a sufficient reproductive compatibility to effect mutual fertilization. In comparison, however, with fertilization in self-pollinated parent plants the respective processes are greatly delayed. Barriers preventing generative reproduction become manifest after the gametic fusion. Disturbances starting at the zygote state brought about gradual embryo abortion; according to Dobzhansky's classification there occurred a so-called hybrid inviability. The initial development of embryos and their following disintegration at various phases, as well as differing effects of reciprocal crosses and endosperm aberrations, show that factors hindering the termination of the hybrid-embryo series of developmental changes are many. The incompatibility of parent genes exhibits its influence by a disturbing action on the initial development of the proembryo and, later, on the suspensor and endosperm. In dependence on this incompatibility the hybrid embryos started to abort earlier or later. In most cases the embryo proper continued to develop only when a long suspensor, peculiar to lupines, drawing it to the chalazal part, was formed. More advanced embryos collapsed because of an underdevelopment and disappearance of endosperm. In no combination of crosses did the endosperm differentiate into a cellular structure. At first it developed as usual, but gradually the nuclei degenerated, and disintegrated, so that finally the entire endosperm disappeared. Embryos, deprived of foodstuffs, died. In the crosses L. albus X L. luteus L. angustifolius X L. luteus L. luteus X L. angustifolius embryos continued to develop for the longest period. They often reached the "spherical" stage, and in some cases even cotyledon primordia were seen. Hybrids might be obtained if the right method of lupine embryo culture during early developmental phases was found. Embryos of species hybrids might then be excised and cultured on artificial media; especially embryos from combinations where part of them develops fairly well and aborts only because of endosperm failure.