Nuclear fusion and non-fusion in theobroma cacao L.

Abstract

CYTOLOGICAL investigations carried out on Theobroma cacao have revealed the fact that the incompatibility reaction in this species is based on non-fusion between male gametes and female haploid nuclei carrying the same dominant S allele1. Incompatibility pollinated cacao ovaries contain approximately 25, 50 or 100 per cent of ovules wherein fusions between the first male gamete and the egg nucleus and between the second male gamete and the polar nuclei have not taken place. In such ovules, the egg and male nuclei appear always to lie in actual contact, each preserving its spherical shape; the second male gamete and the polar nuclei, however, do not show such regularity of behaviour, for the two polar nuclei may sometimes become dissociated from one another, the male nucleus lying elsewhere in the embryo-sac or in contact with one of the separated polar nuclei. © 1959 Nature Publishing Group.