Rice caryopsis as one of the most important food
sources for humans has a complex structure that is composed
of maternal tissues including the pericarp and testa and filial
tissues including the endosperm and embryo. Although rice
caryopsis studies have been conducted previously, a systematic
characterization throughout the entire developmental process
is still lacking. In this study, detailed morphological examinations
of caryopses were made during the entire 30-day
developmental process. We observed some rapid changes in
cell differentiation events and cataloged how cellular degeneration
processes occurred in maternal tissues. The differentiations
of tube cells and cross cells were achieved by
9 days after pollination (DAP). In the testa, the outer
integument was degenerated by 3 DAP, while the outer layer
of the inner integument degenerated by 7 DAP. In the nucellus,
all tissues with the exception of the nucellar projection and the
nucellar epidermis degenerated in the first 5 DAP. By 21 DAP, all
maternal tissues, including vascular bundles, the nucellar
projection and the nucellar epidermal cells were degenerated.
Insummary, this study provides a complete atlas of the dynamic
changes in cell differentiation and degeneration for individual
maternal cell layers of rice caryopsis.