DNA contents and cell number in relation to seed size in the genus Vicia

Abstract

SUMMARYThe extent of variation in cell mass, and in the size of the cell population of cotyledons has been examined to determine their relative roles in the evolution of variation in seed weight within the genus Vicia. In the 12 species examined there were highly significant correlations between seed weight and cotyledon cell number, and between seed weight and mean cell mass. The extremes differed by a factor of 625 fold in dry seed weight; of this variation, most (140 fold) was attributable to variation in the size of the cell population and only a 447-fold change was due to differences in cell mass. The cotyledon cells of all the species, irrespective of their seed weight showed very high levels of replication of their DNA. The implications of these data in terms of the evolution of seed mass in Vicia is considered. There was a constant relationship between cell mass and DNA amount per cell for all species, irrespective of the basic genome size, extent of DNA replication or of the information content of the genome. The basis of this relationship, and its evolutionary implication, is considered.

Natural allelic variation at seed size loci in relation to other life history traits ofArabidopsis thaliana

“…The cell number variation is controlled mainly by maternal factors, whereas the nonmaternal allelic variation affects mostly the cell size, as indicated by the reciprocal crosses. This cell size variation may involve, hypothetically, endoreduplication (48,49).…”

TheAUXIN RESPONSE FACTOR 2gene ofArabidopsislinks auxin signalling, cell division, and the size of seeds and other organs

“…In most monocot species a persistent endosperm forms the bulk of the mature seed, while in most eudicots the endosperm is transient and is replaced by the growing embryo. Therefore, while seed size in monocots such as maize and wheat is often attributable to the extent of endosperm growth (Reddy and Daynard, 1983;Chojecki et al, 1986), in eudicot seeds such as peas and beans, cotyledon cell number has been directly linked to final seed size (Davies, 1975;Davies, 1977). However, in pea, the extent of mitosis in cotyledons is correlated with the extent of invertase activity in the seed coat (Weber et al, 1996), and in the model eudicot Arabidopsis thaliana, endosperm proliferation is correlated with seed weight and embryo size, although the mature seed contains only a single layer of endosperm cells (Scott et al, 1998;Garcia et al, 2003).…”

Sucrose non-fermenting kinase 1 (SnRK1) coordinates metabolic and hormonal signals during pea cotyledon growth and differentiation

“…Understanding the control of mitotic activity is important because cell number determines the final capacity to accumulate dry matter. Studies in Vicia (Davies, 1977), pea (Davies, 1975), soya bean (Glycine max; Egli et al, 1981), wheat (Triticum spp. ; Jenner et al, 1991;Gleadow and Brun, 1982) and maize (Zea mays; Reddy and Daynard, 1983) established a correlation between cell number, seed dry weight and final seed size.…”