Cotyledon cell development in Arabidopsis thaliana during reserve deposition

Abstract

Cotyledon cell development in Arabidopsis thaliana L. during reserve deposition has been analyzed qualitatively and quantitatively. Development has been related to the previously defined time scale for Arabidopsis, hours after flowering. Between 144 and 216 h after flowering the major cell changes in the cotyledon are an increase in the cell volume, a decrease in the volume fraction of cytoplasm and plastids, and an increase in lipid and vacuole volume fractions. The endoplasmic reticulum and dictyosome volume fractions are high during early reserve formation (144 – 168 h after flowering) but decrease significantly thereafter. Evidence as to the origin of the storage lipid is inconclusive, although a dual involvement of plastids and rough endoplasmic reticulum is a likely theory. The 3-nm lipid body membrane, which allows the bodies to retain their individuality during accumulation, is probably a half-unit biological membrane, derived from closely associated rough endoplasmic reticulum cisternae. Much of the evidence obtained in this study indicates that both the endoplasmic reticulum and dictyosomes are involved in protein synthesis and transport to the vacuole. The accumulation of reserves occurs in a well-defined and relatively short period during late embryogenesis (144–216 h after flowering). Key words: Arabidopsis, cotyledons, embryogenesis, reserve deposition, stereology.

Developing Seeds of Arabidopsis Store Different Minerals in Two Types of Vacuoles and in the Endoplasmic Reticulum

“…This finding suggests that the metabolic activity, and therefore the rate of mitochondrial respiration in the embryo cells, is highest during this stage of embryo development. Interestingly, this stage coincides with the filling phases of PSVs and lipid bodies (Mansfield and Briarty, 1992).…”

“…Mn and Zn have been reported to have low to intermediate mobility in the phloem, whereas other essential mineral nutrients, such as K, Mg, P, S, and N, exhibit high mobility (Marschner, 1995). Thus, because the Arabidopsis seed matures in a very short time ‫042ف(‬ to 290 h after fertilization; Mansfield and Briarty, 1992), the endosperm might begin accumulating low/intermediate-mobility minerals soon after fertilization to ensure an adequate supply of these micronutrients for the rapidly developing embryo.…”

Jasmonate Controls Leaf Growth by Repressing Cell Proliferation and the Onset of Endoreduplication while Maintaining a Potential Stand-By Mode

“…The EI represents the average number of endocycles undergone by a given nucleus. This parameter typically increases during leaf development, while cotyledons, where divisions cease before the end of embryo ontogeny and growth depends mainly on cell expansion, show precociously high EI values (Mansfield and Briarty, 1992;Tsukaya, 1994). Plotting the EI obtained from our flow cytometry data ( Fig.…”

Alteration of Seed Fatty Acid Composition by an Ethyl Methanesulfonate-Induced Mutation in Arabidopsis thaliana Affecting Diacylglycerol Acyltransferase Activity

“…Whereas WT seed was mature at 21 d.p.a., the ASll mutant siliques were green and the seeds were still developing, maturing a full 1 week later (28 d.p.a.1. In Arabidopsis as in other oilseeds, the major accumulation of lipid is known to occur in a welldefined and relatively short period during middle to late embryogenesis (Mansfield and Briarty, 1992). This period of maximal lipid deposition (15-18 d.p.a in WT) was also delayed in ASll (21-25 d.p.a.).…”