Seed structure and histochemistry in the palm Euterpe edulis

Abstract

The Euterpe edulis embryo consists of a prominent single cotyledon, a very short radicle-hypocotyl axis and an epicotyl. The epicotyl is obliquely angled with respect to the cotyledon; consequently it corresponds to one of the two categories recognized for palm seeds by DeMason (1988). Parenchyma, protoderm and procambium can be distinguished on the basis of position and shape of their cells, which are highly vacuolated with one central vacuole and the cytoplasm restricted to a thin parietal layer. Initial cells from both apical meristems are also vacuolated but they have small vacuoles distributed around the nuclei. Silica occurs in cell walls of some protodermal cells. Raphides, silica bodies and tannins all occur occasionally in vacuoles, especially in the basal cotyledon region. Most embryo cells lack storage reserves and exhibit an active state, with numerous mitochondria, RER cisternae and Golgi apparatus, indicating a strategy of continuous development without the interposition, at maturity, of a dry state. The endosperm consists of living cells with very large nuclei and thickened cell walls. Similar to the endosperm of other studied palm species, their cells exhibit a quiescent appearance with lipid, protein, minerals (in the cytoplasm) and mannans (in the cell walls) as the insoluble storage reserves.

Enzyme activity and reserve mobilization during Macaw palm ( Acrocomia aculeata ) seed germination

“…The low starch content observed in the embryo from day 0 to 10 indicated that this compound is not a significant reserve compound in macaw palm seeds, as has been reported for other Arecaceae species (DeMason et al 1983;Alang et al 1988;Buckeridge et al 2000;Panza et al 2004). Starch likewise was not detected by histochemical tests in the embryos, nor in the in endosperm tissues of macaw palm seeds (Moura et al 2010).…”

“…Seeds of Arecaceae species can store fatty acids, proteins and, less commonly, starch in granum or in specifi c organelles (DeMason et al 1983;Alang et al 1988;Buckeridge et al 2000;Panza et al 2004). Some palm species produce seeds with endosperm tissues rich in hemicelluloses (DeMason et al 1983;DeMason 1986;Alang et al 1988), placing them in the hard-seed category (Buckeridge 2010).…”

In vitro germination and embryogenic competence acquisition of Euterpe edulis Martius immature zygotic embryos

“…The germination of zygotic embryos of Olea europaea did not depend on the presence of a carbon source in the culture medium, suggesting that the energy required for germination would be supplied by the reserve tissues of the embryo (Garcia et al 2002). However, the accumulation of reserve substances in the embryo of E. edulis seeds is low, since accumulation occurs mainly in the endosperm (Panza et al 2004). The increase in sucrose concentration in MS medium resulted in a higher germination percentage of immature zygotic embryos of E. edulis (Table 1), indicating a possible effect of sucrose on the induction of maturation of the same.…”

Fruit processing and the physiological quality of Euterpe edulis Martius seeds

“…As with most palms, germination of E. edulis is unbalanced and slow (Bovi and Cardoso, 1976;Panza et al, 2004;Roberto and Habermann, 2010;Roberto et al, 2011), and may take from 60 to 90 days, not because the embryo is undeveloped, but because of a physical impediment that hinders the penetration of water (Bovi and Cardoso, 1976). Their thick mesocarp and hard endocarp could act as a barrier to seed imbibition, causing dormancy (Roberto et al, 2011).…”

“…When freshly harvested, seeds have high water content (Brancalion et al, 2011;Roberto et al, 2011) and as shown by research studies on their storage conditions, are recalcitrant due to their sensitivity to dehydration and short life period when stored (Bovi and Cardoso, 1978;Queiroz and Cavalcante, 1986;Reis et al, 1999;Martins et al, 2000;Andrade, 2001). The very small embryo accounts for only 0.54% of the total seed mass and it has only a single prominent cotyledon, a short hypocotyl-radicle axis and epicotyl, storing protein and lipid substances as sources of reserve (Panza et al, 2004).…”