Ovule morphogenesis in normal and mutant Zea mays

Comparison of maize mutants pam1, mac1 and normal plants (variety Belaya noch’) showed that the formation of female reproductive organs is very similar between them. One afunicular ovule develops in an ovary; it is ortho-campylotropous and bitegmic, with a hypostase. The postament, podium and nucellar cap are differentiated in the nucellus. The integuments, epidermal in origin, arise from a common initial zone, but their differentiation is separated in time. In the subepidermal layer of the apical part of the primordium, the complex of initial cells is distinguished. Some of them differentiate as archesporial cells. In normal plants and pam1, only one of them transforms into the megasporocyte, while up to 6-8 do in mac1. Polygonum-type embryo sacs are formed. In pam1 the majority of megasporocytes do not undergo meiosis, while the surrounding ovular tissues continue their development. Analysis of the distribution of polysaccharides and proteins revealed similarities in their spatial and temporal coordination. The differences are quantitative, and probably conditioned by the number of megaspores and embryo sacs.