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An engineered lipid remodeling system using a galactolipid synthase promoter during phosphate starvation enhances oil accumulation in plants.

Shimojima M, Madoka Y, Fujiwara R, Murakawa M, Yoshitake Y, Ikeda K, Koizumi R, Endo K, Ozaki K, Ohta H - Front Plant Sci (2015)

Bottom Line: Thus, the produced galactolipids are transferred to extraplastidial membranes to substitute for phospholipids.Moreover, the Arabidopsis starchless phosphoglucomutase mutant, pgm-1, accumulated higher TAG levels than did wild-type plants under Pi-depleted conditions.We generated transgenic plants that expressed a key gene involved in TAG synthesis using the Pi deficiency-responsive MGD3 promoter in wild-type and pgm-1 backgrounds.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology Yokohama, Japan.

ABSTRACT
Inorganic phosphate (Pi) depletion is a serious problem for plant growth. Membrane lipid remodeling is a defense mechanism that plants use to survive Pi-depleted conditions. During Pi starvation, phospholipids are degraded to supply Pi for other essential biological processes, whereas galactolipid synthesis in plastids is up-regulated via the transcriptional activation of monogalactosyldiacylglycerol synthase 3 (MGD3). Thus, the produced galactolipids are transferred to extraplastidial membranes to substitute for phospholipids. We found that, Pi starvation induced oil accumulation in the vegetative tissues of various seed plants without activating the transcription of enzymes involved in the later steps of triacylglycerol (TAG) biosynthesis. Moreover, the Arabidopsis starchless phosphoglucomutase mutant, pgm-1, accumulated higher TAG levels than did wild-type plants under Pi-depleted conditions. We generated transgenic plants that expressed a key gene involved in TAG synthesis using the Pi deficiency-responsive MGD3 promoter in wild-type and pgm-1 backgrounds. During Pi starvation, the transgenic plants accumulated higher TAG amounts compared with the non-transgenic plants, suggesting that the Pi deficiency-responsive promoter of galactolipid synthase in plastids may be useful for producing transgenic plants that accumulate more oil under Pi-depleted conditions.

No MeSH data available.


Related in: MedlinePlus

Quantitative reverse transcription-PCR analysis of DGAT1, DGAT2, and PDAT1 expression in WT, pgm-1, and transgenic Arabidopsis plants under Pi-sufficient or Pi-depleted conditions. Seedlings (10 d old) of transgenic lines were transferred to MS medium containing 1% (w/v) sucrose, and 0 mM Pi (dark gray bars) or 1 mM Pi (light gray bars) and were grown for 10 d. (A)DGAT1, (B)DGAT2, and (C)PDAT1 mRNA levels in shoots of WT, pgm-1, and transgenic lines in the WT and pgm-1 backgrounds are shown. Line numbers are indicated for each transgenic strain. The expression level of each gene is relative to that in WT under Pi-sufficient conditions. Data are the mean ± SD from three independent experiments. (D) mRNA levels of DGAT1, DGAT2, and PDAT1 in roots of WT plants under Pi-sufficient (+Pi) and Pi-depleted (–Pi) conditions. The expression level of each gene is relative to that in WT under Pi-sufficient conditions. Data are the mean ± SD from three independent experiments.
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Figure 4: Quantitative reverse transcription-PCR analysis of DGAT1, DGAT2, and PDAT1 expression in WT, pgm-1, and transgenic Arabidopsis plants under Pi-sufficient or Pi-depleted conditions. Seedlings (10 d old) of transgenic lines were transferred to MS medium containing 1% (w/v) sucrose, and 0 mM Pi (dark gray bars) or 1 mM Pi (light gray bars) and were grown for 10 d. (A)DGAT1, (B)DGAT2, and (C)PDAT1 mRNA levels in shoots of WT, pgm-1, and transgenic lines in the WT and pgm-1 backgrounds are shown. Line numbers are indicated for each transgenic strain. The expression level of each gene is relative to that in WT under Pi-sufficient conditions. Data are the mean ± SD from three independent experiments. (D) mRNA levels of DGAT1, DGAT2, and PDAT1 in roots of WT plants under Pi-sufficient (+Pi) and Pi-depleted (–Pi) conditions. The expression level of each gene is relative to that in WT under Pi-sufficient conditions. Data are the mean ± SD from three independent experiments.

Mentions: TAG accumulation during senescence is related to the transcriptional up-regulation of DGAT1 (Kaup et al., 2002). TAG accumulation during N starvation occurs with the concomitant induction of the genes involved in TAG synthesis and accumulation, such as DGAT1 and OLEOSIN1 (Yang et al., 2011). Thus, we analyzed the expression of the key TAG biosynthetic genes DGAT1, DGAT2, and PDAT1 in WT and pgm-1 plants under Pi-sufficient and Pi-depleted conditions (Figures 4A–C). Distinct from TAG accumulation during senescence or N starvation, the high TAG accumulation in WT and pgm-1 plants under Pi-depleted conditions (Figure 3C) did not correlate with the transcriptional up-regulation of these genes (Figures 4A–C). The expression levels of these genes in WT roots under Pi-sufficient and Pi-depleted conditions were also analyzed and were clearly shown to be unchanged or decreased during Pi starvation (Figure 4D). These results suggested that the overexpression of these genes under Pi-depleted conditions might further increase TAG levels in the leaves and roots of WT and pgm-1 mutants.


An engineered lipid remodeling system using a galactolipid synthase promoter during phosphate starvation enhances oil accumulation in plants.

Shimojima M, Madoka Y, Fujiwara R, Murakawa M, Yoshitake Y, Ikeda K, Koizumi R, Endo K, Ozaki K, Ohta H - Front Plant Sci (2015)

Quantitative reverse transcription-PCR analysis of DGAT1, DGAT2, and PDAT1 expression in WT, pgm-1, and transgenic Arabidopsis plants under Pi-sufficient or Pi-depleted conditions. Seedlings (10 d old) of transgenic lines were transferred to MS medium containing 1% (w/v) sucrose, and 0 mM Pi (dark gray bars) or 1 mM Pi (light gray bars) and were grown for 10 d. (A)DGAT1, (B)DGAT2, and (C)PDAT1 mRNA levels in shoots of WT, pgm-1, and transgenic lines in the WT and pgm-1 backgrounds are shown. Line numbers are indicated for each transgenic strain. The expression level of each gene is relative to that in WT under Pi-sufficient conditions. Data are the mean ± SD from three independent experiments. (D) mRNA levels of DGAT1, DGAT2, and PDAT1 in roots of WT plants under Pi-sufficient (+Pi) and Pi-depleted (–Pi) conditions. The expression level of each gene is relative to that in WT under Pi-sufficient conditions. Data are the mean ± SD from three independent experiments.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4553410&req=5

Figure 4: Quantitative reverse transcription-PCR analysis of DGAT1, DGAT2, and PDAT1 expression in WT, pgm-1, and transgenic Arabidopsis plants under Pi-sufficient or Pi-depleted conditions. Seedlings (10 d old) of transgenic lines were transferred to MS medium containing 1% (w/v) sucrose, and 0 mM Pi (dark gray bars) or 1 mM Pi (light gray bars) and were grown for 10 d. (A)DGAT1, (B)DGAT2, and (C)PDAT1 mRNA levels in shoots of WT, pgm-1, and transgenic lines in the WT and pgm-1 backgrounds are shown. Line numbers are indicated for each transgenic strain. The expression level of each gene is relative to that in WT under Pi-sufficient conditions. Data are the mean ± SD from three independent experiments. (D) mRNA levels of DGAT1, DGAT2, and PDAT1 in roots of WT plants under Pi-sufficient (+Pi) and Pi-depleted (–Pi) conditions. The expression level of each gene is relative to that in WT under Pi-sufficient conditions. Data are the mean ± SD from three independent experiments.
Mentions: TAG accumulation during senescence is related to the transcriptional up-regulation of DGAT1 (Kaup et al., 2002). TAG accumulation during N starvation occurs with the concomitant induction of the genes involved in TAG synthesis and accumulation, such as DGAT1 and OLEOSIN1 (Yang et al., 2011). Thus, we analyzed the expression of the key TAG biosynthetic genes DGAT1, DGAT2, and PDAT1 in WT and pgm-1 plants under Pi-sufficient and Pi-depleted conditions (Figures 4A–C). Distinct from TAG accumulation during senescence or N starvation, the high TAG accumulation in WT and pgm-1 plants under Pi-depleted conditions (Figure 3C) did not correlate with the transcriptional up-regulation of these genes (Figures 4A–C). The expression levels of these genes in WT roots under Pi-sufficient and Pi-depleted conditions were also analyzed and were clearly shown to be unchanged or decreased during Pi starvation (Figure 4D). These results suggested that the overexpression of these genes under Pi-depleted conditions might further increase TAG levels in the leaves and roots of WT and pgm-1 mutants.

Bottom Line: Thus, the produced galactolipids are transferred to extraplastidial membranes to substitute for phospholipids.Moreover, the Arabidopsis starchless phosphoglucomutase mutant, pgm-1, accumulated higher TAG levels than did wild-type plants under Pi-depleted conditions.We generated transgenic plants that expressed a key gene involved in TAG synthesis using the Pi deficiency-responsive MGD3 promoter in wild-type and pgm-1 backgrounds.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology Yokohama, Japan.

ABSTRACT
Inorganic phosphate (Pi) depletion is a serious problem for plant growth. Membrane lipid remodeling is a defense mechanism that plants use to survive Pi-depleted conditions. During Pi starvation, phospholipids are degraded to supply Pi for other essential biological processes, whereas galactolipid synthesis in plastids is up-regulated via the transcriptional activation of monogalactosyldiacylglycerol synthase 3 (MGD3). Thus, the produced galactolipids are transferred to extraplastidial membranes to substitute for phospholipids. We found that, Pi starvation induced oil accumulation in the vegetative tissues of various seed plants without activating the transcription of enzymes involved in the later steps of triacylglycerol (TAG) biosynthesis. Moreover, the Arabidopsis starchless phosphoglucomutase mutant, pgm-1, accumulated higher TAG levels than did wild-type plants under Pi-depleted conditions. We generated transgenic plants that expressed a key gene involved in TAG synthesis using the Pi deficiency-responsive MGD3 promoter in wild-type and pgm-1 backgrounds. During Pi starvation, the transgenic plants accumulated higher TAG amounts compared with the non-transgenic plants, suggesting that the Pi deficiency-responsive promoter of galactolipid synthase in plastids may be useful for producing transgenic plants that accumulate more oil under Pi-depleted conditions.

No MeSH data available.


Related in: MedlinePlus