Variations of endoreduplication and its potential contribution to endosperm development in rice (Oryza sativa L.)

Abstract

Endoreduplication is the phenomenon by which cells increase their ploidy. Endoreduplication is initiated by the transition from the mitotic cell cycle to the endocycle, in which DNA replication occurs without a subsequent chromosome separation and cytokinesis, and is enhanced by endocycle reiteration. This process appears to play an important role in endosperm development, but the characteristics of endoreduplication in the endosperm of rice (Oryza sativa) remain unclear. To elucidate the features and variations of endoreduplication in rice endosperm, endoreduplication progression in the developing endosperm was compared among 10 cultivars based on flow cytometry and fluorescence microscopy. The flow cytometric analysis detected significant differences among 10 cultivars in the following three parameters: mean ploidy of all nuclei, the proportion of nuclei ≥6C (%E, an estimate of the initiation of the endocycle), and the mean ploidy of nuclei ≥6C (E6P, an estimate of the reiteration of the endocycle). However, no significant correlation between %E and E6P was observed, suggesting that the initiation and reiteration of the endocycle are independently regulated. Fluorescence microscopy revealed that the ploidy of the nuclei was higher in the intermediate region than in the central and peripheral regions of the endosperm. Cells with a higher ploidy were larger in the developing endosperm. Furthermore, the mean ploidy in the developing endosperm was significantly correlated with the mean cell size in the mature endosperm. These results indicate that endoreduplication progression in the endosperm differed significantly among the 10 rice cultivars and such differences may influence endosperm cell size.

Endopolyploidy Variation in Wild Barley Seeds across Environmental Gradients in Israel

“…We found that during seed development, both wild and cultivated barley endosperm underwent two rounds of endoreduplication resulting in 12C and 24C nuclei, respectively [ 11 ]. Two endocycles also appeared during wheat [ 46 ] and rice [ 47 ] endosperm development. Four and up to seven rounds of endoreduplication were found in the endosperm of sorghum [ 48 ] and maize [ 49 ], respectively.…”

Endoreplication—Why Are We Not Using Its Full Application Potential?

“…Also, endoreplication characterizing one species may be very diverse and specific. Endoreduplication progression in the endosperm differed significantly among the 10 rice cultivars researched by Kobayashi in 2019 [101].…”

“…They occur in large numbers and are characterized by a diversity of alleles and interactions depending on the taxon [4,71,95,100]. The proper harmonization of all this machinery is quite challenging, which limits the incidence of endocycles [101,102].…”

The role of APC/C in cell cycle dynamics, growth and development in cereal crops

“…The endosperm accounts for most of the seed’s volume. Its shape and size are highly determined by cell size through growth and expansion ( Kobayashi, 2019 ), as well as by a large accumulation of storage compounds, like carbohydrates, proteins, and/or lipids, and water ( Dante et al., 2014a ; Hands et al., 2016 ). Grass endosperm development has several distinct phases, which can overlap considerably, such as early development, differentiation, periods of mitosis and later endoreduplication, accumulation of storage compounds, and maturation ( Sabelli and Larkins, 2009 ).…”

“…The endoreduplication process has been extensively described in monocot species ( Sabelli and Larkins, 2009 ), displaying a huge impact on their cell’s ploidy level ( Dante et al., 2014b ). The endoreduplication cycle occurs during the transition from the mitotic cell cycle to a modified cycle called endocycle, during which DNA re-replication is stimulated without subsequent chromosome segregation and cytokinesis ( Kobayashi, 2019 ). In this process, the chromatids are duplicated exponentially, while the number of chromosomes remains unchanged ( Edgar and Orr-Weaver, 2001 ).…”