Endosperm Morphogenesis in Wheat: Transfer of Nutrients from the Antipodals to the Lower Endosperm1
- A. G. Huber and
- D. F. Grabe2
The morphogenesis of early cell formation in the endosperm of wheat (Triticum aestivum L.) was studied by light microscopy. The objective of this study was to provide a description of endosperm cell formation and corresponding changes in the surrounding diploid and haploid tissues during the first 4 days of wheat endosperm growth. Entire spikelets of large-kerneled, soft white winter and small-kerneled hard red winter wheat cultivars were harvested daily, embedded in paraffin, and sectioned longitudinally. The microscopic sections provided a series of photographs documenting the continuous development of the endosperm, embryo sac, and maternal tissues during their early growth. During the first 4 days of development, dense endosperm cells were formed in the lower one-fourth of the embryo sac, immediately above the embryo. The cytoplasm that made up those cells came from endosperm vesicles formed higher in the embryo sac. These vesicles were formed in the free nuclear endosperm bordering the antipodals. As the vesicles enlarged, they became spherical, were freed, and fell to the gravitational bottom of the embryo sac. There they coalesced, in an appropriate position to be used as nourishment for the embryo. During the period of endosperm vesicle formation, there was concurrent degeneration of the antipodals. By the end of the fourth day postanthesis (PA), the antipodals had been largely consumed and vesicle formation had stopped. Also by that time, walls had grown in from the nucellus and had partitioned the mass of nucleate cytoplasm, above the embryo, into endosperm cells. By 15 days PA, these cells had been consumed entirely by the developing embryo. Cytoplasmic vesicles were found to be the developmental mechanism by which nutrients are transferred from the antipodals to the lower endosperm and ultimately to the embryo.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © . .