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Female germ unit in Genlisea and Utricularia, with remarks about the evolution of the extra-ovular female gametophyte in members of Lentibulariaceae.

Płachno BJ - Protoplasma (2010)

Bottom Line: The present studies clearly show that synergids in both genera possess a filiform apparatus; however, it seems that Utricularia quelchii synergids have a simpler structure compared to Genlisea aurea and other typical angiosperms.This ancestral characteristic still occurs in some species from the Bivalvaria subgenus.An embryo sac, which grows out beyond the limit of the integument and has contact with nutritive tissue, appeared independently in different Utricularia lineages and as a consequence of this, the egg apparatus changes position from apical to lateral.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Cytology and Embryology, Jagiellonian University, 52 Grodzka st., 31-044, Cracow, Poland. bartek78pl@poczta.onet.pl

ABSTRACT
Lentibulariaceae is the largest family among carnivorous plants which displays not only an unusual morphology and anatomy but also the special evolution of its embryological characteristics. It has previously been reported by authors that Utricularia species lack a filiform apparatus in the synergids. The main purposes of this study were to determine whether a filiform apparatus occurs in the synergids of Utricularia and its sister genus Genlisea, and to compare the female germ unit in these genera. The present studies clearly show that synergids in both genera possess a filiform apparatus; however, it seems that Utricularia quelchii synergids have a simpler structure compared to Genlisea aurea and other typical angiosperms. The synergids are located at the terminal position in the embryo sacs of Pinguicula, Genlisea and were probably also located in that position in common Utricularia ancestor. This ancestral characteristic still occurs in some species from the Bivalvaria subgenus. An embryo sac, which grows out beyond the limit of the integument and has contact with nutritive tissue, appeared independently in different Utricularia lineages and as a consequence of this, the egg apparatus changes position from apical to lateral.

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Ultrastructure of a U. quelchii egg cell and central cell. a The micropylar part of the egg cell; Eg egg cell, En egg nucleus, m mitochondrion, d dictyosome, P plastid, Cc central cell, framed part shows microtubules near the egg plasma membrane, bar = 0.6 μm. b Polar nuclei during fusion; red arrows nuclear bridges, m mitochondrion, d dictyosome, bar = 0.4 μm. c The central cell with a secondary nucleus; m mitochondrion, S starch grain in an amyloplast, N secondary nucleus, bar = 0.9 μm
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Fig7: Ultrastructure of a U. quelchii egg cell and central cell. a The micropylar part of the egg cell; Eg egg cell, En egg nucleus, m mitochondrion, d dictyosome, P plastid, Cc central cell, framed part shows microtubules near the egg plasma membrane, bar = 0.6 μm. b Polar nuclei during fusion; red arrows nuclear bridges, m mitochondrion, d dictyosome, bar = 0.4 μm. c The central cell with a secondary nucleus; m mitochondrion, S starch grain in an amyloplast, N secondary nucleus, bar = 0.9 μm

Mentions: The central cell seems to be the most active part of the female gametophyte. Its cytoplasm is full of mitochondria, dictyosomes, and plastids (Fig. 3c–d), and also in the micropylar part (Fig. 2b). The dictyosomes are very active in the production of large vesicles with an electron-translucent context; these vesicles fuse forming vacuoles. endoplasmic reticulum (ER) and microbodies also occur. Large polar nuclei occur near the vicinity of the egg cell (Fig. 3c); they later fuse creating a secondary nucleus (Fig. 4a–b). There are numerous microtubules in the cortical cytoplasm there are numerous microtubules (Fig. 4c), some of them lying parallel to the plasma membrane. The central cell is highly vacuolated in the chalazal part (not shown).


Female germ unit in Genlisea and Utricularia, with remarks about the evolution of the extra-ovular female gametophyte in members of Lentibulariaceae.

Płachno BJ - Protoplasma (2010)

Ultrastructure of a U. quelchii egg cell and central cell. a The micropylar part of the egg cell; Eg egg cell, En egg nucleus, m mitochondrion, d dictyosome, P plastid, Cc central cell, framed part shows microtubules near the egg plasma membrane, bar = 0.6 μm. b Polar nuclei during fusion; red arrows nuclear bridges, m mitochondrion, d dictyosome, bar = 0.4 μm. c The central cell with a secondary nucleus; m mitochondrion, S starch grain in an amyloplast, N secondary nucleus, bar = 0.9 μm
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3066386&req=5

Fig7: Ultrastructure of a U. quelchii egg cell and central cell. a The micropylar part of the egg cell; Eg egg cell, En egg nucleus, m mitochondrion, d dictyosome, P plastid, Cc central cell, framed part shows microtubules near the egg plasma membrane, bar = 0.6 μm. b Polar nuclei during fusion; red arrows nuclear bridges, m mitochondrion, d dictyosome, bar = 0.4 μm. c The central cell with a secondary nucleus; m mitochondrion, S starch grain in an amyloplast, N secondary nucleus, bar = 0.9 μm
Mentions: The central cell seems to be the most active part of the female gametophyte. Its cytoplasm is full of mitochondria, dictyosomes, and plastids (Fig. 3c–d), and also in the micropylar part (Fig. 2b). The dictyosomes are very active in the production of large vesicles with an electron-translucent context; these vesicles fuse forming vacuoles. endoplasmic reticulum (ER) and microbodies also occur. Large polar nuclei occur near the vicinity of the egg cell (Fig. 3c); they later fuse creating a secondary nucleus (Fig. 4a–b). There are numerous microtubules in the cortical cytoplasm there are numerous microtubules (Fig. 4c), some of them lying parallel to the plasma membrane. The central cell is highly vacuolated in the chalazal part (not shown).

Bottom Line: The present studies clearly show that synergids in both genera possess a filiform apparatus; however, it seems that Utricularia quelchii synergids have a simpler structure compared to Genlisea aurea and other typical angiosperms.This ancestral characteristic still occurs in some species from the Bivalvaria subgenus.An embryo sac, which grows out beyond the limit of the integument and has contact with nutritive tissue, appeared independently in different Utricularia lineages and as a consequence of this, the egg apparatus changes position from apical to lateral.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Cytology and Embryology, Jagiellonian University, 52 Grodzka st., 31-044, Cracow, Poland. bartek78pl@poczta.onet.pl

ABSTRACT
Lentibulariaceae is the largest family among carnivorous plants which displays not only an unusual morphology and anatomy but also the special evolution of its embryological characteristics. It has previously been reported by authors that Utricularia species lack a filiform apparatus in the synergids. The main purposes of this study were to determine whether a filiform apparatus occurs in the synergids of Utricularia and its sister genus Genlisea, and to compare the female germ unit in these genera. The present studies clearly show that synergids in both genera possess a filiform apparatus; however, it seems that Utricularia quelchii synergids have a simpler structure compared to Genlisea aurea and other typical angiosperms. The synergids are located at the terminal position in the embryo sacs of Pinguicula, Genlisea and were probably also located in that position in common Utricularia ancestor. This ancestral characteristic still occurs in some species from the Bivalvaria subgenus. An embryo sac, which grows out beyond the limit of the integument and has contact with nutritive tissue, appeared independently in different Utricularia lineages and as a consequence of this, the egg apparatus changes position from apical to lateral.

Show MeSH
Related in: MedlinePlus