Development of female and male reproductive structures in <I>Borodinia macrophylla</I> (Brassicaceae)

Abstract

For the first time, cytoembryological study of the female and male reproductive structures development in the East Siberian endemic, Borodinia macrophylla (Turcz.) O.E. Schulz (order Capparales, family Brassicaceae, tribe Boechereae), is presented. The general plan of the reproductive structures development occurs similarly to the studied species of Boechera. The anther contains 4 microsporangia with four layers, namely epidermis, endothecium, middle layer, and tapetum at the beginning of development; as the anther matures, the wall becomes two-layered. The anther tapetum is unevenly 2-layered, microsporocytes develop simultaneously; most pollen grains in mature anthers are bicellular. The ovule is ortho-campylotropous, bitegmic, medionucellate. The embryo sac is 7-celled, 8-nucleate, formed according to the monosporic Polygonum type. The polar nuclei of the central cell in the mature embryo sac do not fuse. Female gametophytes developed in all the ovules studied. In B. macrophylla, only a sexual mode of reproduction was observed; no apomictic development was detected.