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Overexpression of a truncated CTF7 construct leads to pleiotropic defects in reproduction and vegetative growth in Arabidopsis.

Liu D, Makaroff CA - BMC Plant Biol. (2015)

Bottom Line: Inactivation of Arabidopsis CTF7 (AtCTF7) results in severe defects in reproduction and vegetative growth.Transgenic plants expressing 35S:AtCTF7∆B displayed similar vegetative defects, suggesting the defects in 35S:NTAP:AtCTF7∆B plants are caused by high-level expression of AtCTF7∆B.High level expression of AtCTF7∆B disrupts megasporogenesis, megagametogenesis and male meiosis, as well as causing a broad range of vegetative defects, including dwarfism that are inherited in a non-Mendelian fashion.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Eco1/Ctf7 is essential for the establishment of sister chromatid cohesion during S phase of the cell cycle. Inactivation of Ctf7/Eco1 leads to a lethal phenotype in most organisms. Altering Eco1/Ctf7 levels or point mutations in the gene can lead to alterations in nuclear division as well as a wide range of developmental defects. Inactivation of Arabidopsis CTF7 (AtCTF7) results in severe defects in reproduction and vegetative growth.

Results: To further investigate the function(s) of AtCTF7, a tagged version of AtCTF7 and several AtCTF7 deletion constructs were created and transformed into wild type or ctf7 +/- plants. Transgenic plants expressing 35S:NTAP:AtCTF7∆299-345 (AtCTF7∆B) displayed a wide range of phenotypic alterations in reproduction and vegetative growth. Male meiocytes exhibited chromosome fragmentation and uneven chromosome segregation. Mutant ovules contained abnormal megasporocyte-like cells during pre-meiosis, megaspores experienced elongated meiosis and megagametogenesis, and defective megaspores/embryo sacs were produced at various stages. The transgenic plants also exhibited a broad range of vegetative defects, including meristem disruption and dwarfism that were inherited in a non-Mendelian fashion. Transcripts for epigenetically regulated transposable elements (TEs) were elevated in transgenic plants. Transgenic plants expressing 35S:AtCTF7∆B displayed similar vegetative defects, suggesting the defects in 35S:NTAP:AtCTF7∆B plants are caused by high-level expression of AtCTF7∆B.

Conclusions: High level expression of AtCTF7∆B disrupts megasporogenesis, megagametogenesis and male meiosis, as well as causing a broad range of vegetative defects, including dwarfism that are inherited in a non-Mendelian fashion.

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35S:NTAP:AtCTF7∆B male meiocytes exhibit defective meiotic chromosome segregation. (A-D) and (I-L) Wild type meiocytes. (E-H) and (M-P) 35S:NTAP:AtCTF7∆B meiocytes. A, E pachytene; B, F diakinesis; C, G metaphase I; D, H telophase I; I, M prophase II; J, N metaphase II; K, O anaphase II; L, P telophase II. Lagging chromosomes and/or chromosome fragments are denoted with arrows. Meiotic chromosomes are stained by 4’, 6-diamidino-2-phenylindole (DAPI). Scale bar = 10 μm.
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Fig2: 35S:NTAP:AtCTF7∆B male meiocytes exhibit defective meiotic chromosome segregation. (A-D) and (I-L) Wild type meiocytes. (E-H) and (M-P) 35S:NTAP:AtCTF7∆B meiocytes. A, E pachytene; B, F diakinesis; C, G metaphase I; D, H telophase I; I, M prophase II; J, N metaphase II; K, O anaphase II; L, P telophase II. Lagging chromosomes and/or chromosome fragments are denoted with arrows. Meiotic chromosomes are stained by 4’, 6-diamidino-2-phenylindole (DAPI). Scale bar = 10 μm.

Mentions: Male meiocytes in 35S:NTAP:AtCTF7∆B plants resembled wild type during early stages of meiosis, with normal chromosome morphology during pachytene (Figure 2A,E), diakinesis (Figure 2B,F) and metaphase I (Figure 2C,G). The first noticeable defect was observed at telophase I when lagging chromosomes were observed (Figure 2D,H), followed by mis-segregated chromosomes at prophase II (Figure 2M). More than twenty individual chromosomes were typically observed in meiocytes beginning at metaphase II (Figure 2N), indicating that sister chromatid cohesion was prematurely lost. Chromosomes did not segregate evenly at anaphase II (Figure 2O) resulting in the production of polyads with varying DNA contents at tetrad stage (Figure 2P). Similar to atctf7 plants, a small number of relatively normal meiocytes were also observed throughout meiosis with fewer normal-appearing meiocytes in later stages of meiosis. For example, the percentages of defective meiocytes observed at various stages of meiosis in Line 11 were: metaphase I: 0% (0/41), telophase I: 6.8% (7/87), prophase II: 23.5% (24/102), metaphase II: 40.7% (24/59), anaphase II: 56.8% (25/44) and telophase II: 64.0% (114/178).Figure 2


Overexpression of a truncated CTF7 construct leads to pleiotropic defects in reproduction and vegetative growth in Arabidopsis.

Liu D, Makaroff CA - BMC Plant Biol. (2015)

35S:NTAP:AtCTF7∆B male meiocytes exhibit defective meiotic chromosome segregation. (A-D) and (I-L) Wild type meiocytes. (E-H) and (M-P) 35S:NTAP:AtCTF7∆B meiocytes. A, E pachytene; B, F diakinesis; C, G metaphase I; D, H telophase I; I, M prophase II; J, N metaphase II; K, O anaphase II; L, P telophase II. Lagging chromosomes and/or chromosome fragments are denoted with arrows. Meiotic chromosomes are stained by 4’, 6-diamidino-2-phenylindole (DAPI). Scale bar = 10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4359560&req=5

Fig2: 35S:NTAP:AtCTF7∆B male meiocytes exhibit defective meiotic chromosome segregation. (A-D) and (I-L) Wild type meiocytes. (E-H) and (M-P) 35S:NTAP:AtCTF7∆B meiocytes. A, E pachytene; B, F diakinesis; C, G metaphase I; D, H telophase I; I, M prophase II; J, N metaphase II; K, O anaphase II; L, P telophase II. Lagging chromosomes and/or chromosome fragments are denoted with arrows. Meiotic chromosomes are stained by 4’, 6-diamidino-2-phenylindole (DAPI). Scale bar = 10 μm.
Mentions: Male meiocytes in 35S:NTAP:AtCTF7∆B plants resembled wild type during early stages of meiosis, with normal chromosome morphology during pachytene (Figure 2A,E), diakinesis (Figure 2B,F) and metaphase I (Figure 2C,G). The first noticeable defect was observed at telophase I when lagging chromosomes were observed (Figure 2D,H), followed by mis-segregated chromosomes at prophase II (Figure 2M). More than twenty individual chromosomes were typically observed in meiocytes beginning at metaphase II (Figure 2N), indicating that sister chromatid cohesion was prematurely lost. Chromosomes did not segregate evenly at anaphase II (Figure 2O) resulting in the production of polyads with varying DNA contents at tetrad stage (Figure 2P). Similar to atctf7 plants, a small number of relatively normal meiocytes were also observed throughout meiosis with fewer normal-appearing meiocytes in later stages of meiosis. For example, the percentages of defective meiocytes observed at various stages of meiosis in Line 11 were: metaphase I: 0% (0/41), telophase I: 6.8% (7/87), prophase II: 23.5% (24/102), metaphase II: 40.7% (24/59), anaphase II: 56.8% (25/44) and telophase II: 64.0% (114/178).Figure 2

Bottom Line: Inactivation of Arabidopsis CTF7 (AtCTF7) results in severe defects in reproduction and vegetative growth.Transgenic plants expressing 35S:AtCTF7∆B displayed similar vegetative defects, suggesting the defects in 35S:NTAP:AtCTF7∆B plants are caused by high-level expression of AtCTF7∆B.High level expression of AtCTF7∆B disrupts megasporogenesis, megagametogenesis and male meiosis, as well as causing a broad range of vegetative defects, including dwarfism that are inherited in a non-Mendelian fashion.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Eco1/Ctf7 is essential for the establishment of sister chromatid cohesion during S phase of the cell cycle. Inactivation of Ctf7/Eco1 leads to a lethal phenotype in most organisms. Altering Eco1/Ctf7 levels or point mutations in the gene can lead to alterations in nuclear division as well as a wide range of developmental defects. Inactivation of Arabidopsis CTF7 (AtCTF7) results in severe defects in reproduction and vegetative growth.

Results: To further investigate the function(s) of AtCTF7, a tagged version of AtCTF7 and several AtCTF7 deletion constructs were created and transformed into wild type or ctf7 +/- plants. Transgenic plants expressing 35S:NTAP:AtCTF7∆299-345 (AtCTF7∆B) displayed a wide range of phenotypic alterations in reproduction and vegetative growth. Male meiocytes exhibited chromosome fragmentation and uneven chromosome segregation. Mutant ovules contained abnormal megasporocyte-like cells during pre-meiosis, megaspores experienced elongated meiosis and megagametogenesis, and defective megaspores/embryo sacs were produced at various stages. The transgenic plants also exhibited a broad range of vegetative defects, including meristem disruption and dwarfism that were inherited in a non-Mendelian fashion. Transcripts for epigenetically regulated transposable elements (TEs) were elevated in transgenic plants. Transgenic plants expressing 35S:AtCTF7∆B displayed similar vegetative defects, suggesting the defects in 35S:NTAP:AtCTF7∆B plants are caused by high-level expression of AtCTF7∆B.

Conclusions: High level expression of AtCTF7∆B disrupts megasporogenesis, megagametogenesis and male meiosis, as well as causing a broad range of vegetative defects, including dwarfism that are inherited in a non-Mendelian fashion.

Show MeSH
Related in: MedlinePlus