Development of male and female gametophytes and embryogenesis in the Arabidopsis thaliana

Abstract

Sporogenesis and gametophytes development in Arabidopsis thaliana (Brassicaceae) was studied. Arabidopsis thaliana was selected for this study as a biogenetic model with a small genome and a short life cycle. Flowers and buds in different developmental stages were removed, fixed in an FAA70, stored in 70 % ethanol, embedded in paraffin and sectioned at 7 − 10 µm with a microtome, stained with Hematoxylin – Eosin and analyzed with a photomicroscope. The results showed the anthers are tetrasporangiate, anther tapetum is of secretory type at the beginning and plasmodial at the end of anther development. Also, microspore tetrads are tetrahedral and rarely tetragonal. In addition, mature pollen grains are spherical, tricolporate, scabrate, and tricellular. The gynoecium is bicarpellate and the ovule is amphitropous, bitegmic, and tenuinucellate. Hypostasis was also observed in basis of nucellus. Endothelium is composed of one cell row and cell divisions of megaspore mother cell results in T-shaped tetrad. The chalazal cell is a functional megaspore that survives and functions in megagametophyte development. The embryo sac development belonged to the Polygonum type and it is curved. The mature embryo sac is composed of 7 cells, one central cell containing polar nuclei, two elongated synergids, a triangular oosphere cell, and three antipodal cells that are degenerated immediately by developing the embryogenesis stage in the mature embryo.