Maternal genotype influences pea seed size by controlling both mitotic activity during early embryogenesis and final endoreduplication level/cotyledon cell size in mature seed

Abstract

When reciprocal crosses are made between different pea genotypes, there is a strong maternal influence on mature seed size of the reciprocal hybrids, i.e. their dry weights are similar to that of seeds obtained from their maternal parents. Reciprocal crosses between pea varieties having very different mature seed sizes were used to investigate how the maternal genotype controls seed development and mature seed size. The differences in dry seed weight between genotypes and reciprocal hybrids reflected differences in both cotyledon cell number and mean cell volume, and the maternal control on the establishment of these two traits was investigated. Using flow cytometry, data relative to endoreduplication kinetics in cotyledons during the transition between the cell division phase and maturation were obtained. The appearance of nuclei having an 8C DNA content indicates the initiation of the endoreduplication phenomenon and thus the end of the cell division phase. It was shown that the duration of the cell division phase was the same in the reciprocal hybrids, its value being intermediate between those recorded for their maternal parents. This result indicates that the timing of development of the embryo is not under maternal control, but depends on its own genotype. Consequently, maternal genotype must influence the mitotic rate during the cell division phase to achieve differences in cell number found in the cotyledons of mature F1-reciprocal hybrids. The final level of endoreduplication in cotyledons of mature seeds was also investigated. This study showed that there is a close relationship (r2 = 0.919) between the endoreduplication level in mature cotyledons and seed dry weight or mean volume of cotyledon cells, suggesting that both maternal and non-maternal factors could control the number of endoreduplicating cycles in the cotyledons and, hypothetically, the cotyledon cell size.

Increasing seed size and quality by manipulating BIG SEEDS1 in legume species

“…1 D and E). These results are consistent with the notion that seed size in legume species is strongly and positively correlated with cotyledon size (8,9). Analyses of cross-sections showed that the size of spongy and palisade mesophyll cells of cotyledons was indistinguishable between the mtbs1-1 mutant and WT ( Fig.…”

Micropropagation of Viola uliginosa (Violaceae) for endangered species conservation and for somaclonal variation-enhanced cyclotide biosynthesis

“…8C ? 16C)/2C ratio, and the mean C-value (mean ploidy; Lemontey et al 2000) were established. Nuclei having at least 8C DNA content were considered to be endopolyploid.…”

A Dominant Negative Mutant of Cyclin-Dependent Kinase A Reduces Endoreduplication but Not Cell Size or Gene Expression in Maize Endosperm

“…In animals, endoreduplication occurs in a variety of cells and tissues, where it is thought to be related to differentiation, cell size, and the level of gene expression (White, 1973;Zimmet and Ravid, 2000). In plants, endoreduplication occurs in cells of vegetative tissues Cebolla et al, 1999) as well those related to flowering (Kudo and Kimura, 2002), embryogenesis (Nagl, 1974;Lemontey et al, 2000), endosperm development (Kowles and Phillips, 1985), and fruit formation (Joubè s et al, 1999). Despite its widespread occurrence in plants, the function of endoreduplication and mechanism(s) by which it occurs remain poorly understood.…”

“…Based on its temporal relationship with cell expansion and increased metabolic activity, endoreduplication is generally thought to provide a mechanism for increasing cell size and gene transcription (Sugimoto-Shirasu and Roberts, 2003). Notably, the degree to which endoreduplication occurs in seed storage tissues has been correlated with the accumulation of starch and storage proteins as well as yield (Kowles et al, 1992;Cavallini et al, 1995;Lemontey et al, 2000).…”