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Expression profiling of ascorbic acid-related genes during tomato fruit development and ripening and in response to stress conditions.

Ioannidi E, Kalamaki MS, Engineer C, Pateraki I, Alexandrou D, Mellidou I, Giovannonni J, Kanellis AK - J. Exp. Bot. (2009)

Bottom Line: L-ascorbate (the reduced form of vitamin C) participates in diverse biological processes including pathogen defence mechanisms, and the modulation of plant growth and morphology, and also acts as an enzyme cofactor and redox status indicator.Important aspects of the hypoxic and post-anoxic response in tomato fruit are discussed.The data suggest that L-galactose-1-phosphate phosphatase could play an important role in regulating ascorbic acid accumulation during tomato fruit development and ripening.

View Article: PubMed Central - PubMed

Affiliation: Group of Biotechnology of Pharmaceutical Plants, Division of Pharmacognosy-Pharmacology, Department of Pharmaceutical Sciences, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.

ABSTRACT
L-ascorbate (the reduced form of vitamin C) participates in diverse biological processes including pathogen defence mechanisms, and the modulation of plant growth and morphology, and also acts as an enzyme cofactor and redox status indicator. One of its chief biological functions is as an antioxidant. L-ascorbate intake has been implicated in the prevention/alleviation of varied human ailments and diseases including cancer. To study the regulation of accumulation of this important nutraceutical in fruit, the expression of 24 tomato (Solanum lycopersicon) genes involved in the biosynthesis, oxidation, and recycling of L-ascorbate during the development and ripening of fruit have been characterized. Taken together with L-ascorbate abundance data, the results show distinct changes in the expression profiles for these genes, implicating them in nodal regulatory roles during the process of L-ascorbate accumulation in tomato fruit. The expression of these genes was further studied in the context of abiotic and post-harvest stress, including the effects of heat, cold, wounding, oxygen supply, and ethylene. Important aspects of the hypoxic and post-anoxic response in tomato fruit are discussed. The data suggest that L-galactose-1-phosphate phosphatase could play an important role in regulating ascorbic acid accumulation during tomato fruit development and ripening.

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Related in: MedlinePlus

Expression of AA biosynthetic, oxidation, and recycling genes in response to post-anoxic conditions. Total RNA isolated from the fruit shown in Fig. 5 was isolated, fractionated in denaturing agarose gels, transferred to Hybond N-membranes, and hybridized with specific 32P-radiolabelled probes corresponding to ascorbate biosynthetic genes (A) and oxidation and recycling genes (B). Staining with 0.04% methylene blue was performed to verify the uniformity of RNA loading on the gel. All experiments were performed in triplicate.
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fig6: Expression of AA biosynthetic, oxidation, and recycling genes in response to post-anoxic conditions. Total RNA isolated from the fruit shown in Fig. 5 was isolated, fractionated in denaturing agarose gels, transferred to Hybond N-membranes, and hybridized with specific 32P-radiolabelled probes corresponding to ascorbate biosynthetic genes (A) and oxidation and recycling genes (B). Staining with 0.04% methylene blue was performed to verify the uniformity of RNA loading on the gel. All experiments were performed in triplicate.

Mentions: Mature green tomatoes were subjected to a 100% nitrogen atmosphere (anoxia) for 48 h and subsequently returned to air for 48 h, and AA content and the expression profiles of ascorbate biosynthetic, oxidizing, and recycling genes, as well as APX and SOD were studied (see below). As illustrated in Fig. 5A and B, the post-anoxic stress caused the AA levels to increase ∼8-fold at 3–6 h after re-exposure to air, suggesting an increased need for this antioxidant in order to compensate for the presumed increased amounts of ROS. However, a subsequent dramatic and continuous decrease in AA content was observed after 6 h and up to 48 h, suggesting the participation of ascorbate in the ROS scavenging activity. At the same time, AA in control mature green fruit markedly increased during the first hour and then declined before increasing again after 12 h. Regarding the expression profiles of the AA genes, it is intriguing to note that this stress triggered the induction of gene expression of all enzymes participating in AA biosynthesis (Fig. 6A). The transcript levels of most of the genes were evident after 3 h and peaked at 12 h upon re-exposure to air, coinciding with the elevated content of AA. Specifically, the steady-state level of GPI and PMM mRNAs peaked 12 h after re-exposure to air. Similarly, PMI transcript peaked at 12–24 h upon re-exposure to air. A peak at 12 h after exposure to air was also observed in the expression of GMP, GME, L-GalDH L-GalLDH, and AKR1 and 2. AKR38 was already highly expressed while in anoxia and remained unchanged up to 24 h in air, and then decreased. GPP transcript was present at low levels at 1 h and 3 h post-hypoxia, increased at 12 h, and peaked at 48 h after re-exposure to air. The level of these transcripts in the control group that was only exposed to air exhibited a rhythmicity during the time course of the experiment; expression was high at 0 h and dropped at 1 h, but was high again at 3 h and 6 h; expression was again low at 12 h and high at 24 h and 48 h. In fact, such rhythmicity is also seen in the expression of Arabidopsis GPP (unpublished microarray results available at Affymetrix online, experiment #149 conducted by Kieron Edwards and Andrew Millar). The Arabidopsis gene also showed sharp increases and declines within 6 h time frames. The transcripts of tomato GGP increased dramatically 3 h after transfer to air from the anoxia treatment. Expression levels dropped 24 h after transfer to air. The air controls exhibited a low steady-state level of expression which peaks at 1, 24, and 48 h after transfer to air, again indicating a rhythmic expression pattern for this gene. Transcripts showing homology with MIOX showed high accumulation of their mRNA after 48 h in anoxia, but decreased sharply as soon as the fruit were transferred back to air, and were almost undetectable after 12 h.


Expression profiling of ascorbic acid-related genes during tomato fruit development and ripening and in response to stress conditions.

Ioannidi E, Kalamaki MS, Engineer C, Pateraki I, Alexandrou D, Mellidou I, Giovannonni J, Kanellis AK - J. Exp. Bot. (2009)

Expression of AA biosynthetic, oxidation, and recycling genes in response to post-anoxic conditions. Total RNA isolated from the fruit shown in Fig. 5 was isolated, fractionated in denaturing agarose gels, transferred to Hybond N-membranes, and hybridized with specific 32P-radiolabelled probes corresponding to ascorbate biosynthetic genes (A) and oxidation and recycling genes (B). Staining with 0.04% methylene blue was performed to verify the uniformity of RNA loading on the gel. All experiments were performed in triplicate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2651456&req=5

fig6: Expression of AA biosynthetic, oxidation, and recycling genes in response to post-anoxic conditions. Total RNA isolated from the fruit shown in Fig. 5 was isolated, fractionated in denaturing agarose gels, transferred to Hybond N-membranes, and hybridized with specific 32P-radiolabelled probes corresponding to ascorbate biosynthetic genes (A) and oxidation and recycling genes (B). Staining with 0.04% methylene blue was performed to verify the uniformity of RNA loading on the gel. All experiments were performed in triplicate.
Mentions: Mature green tomatoes were subjected to a 100% nitrogen atmosphere (anoxia) for 48 h and subsequently returned to air for 48 h, and AA content and the expression profiles of ascorbate biosynthetic, oxidizing, and recycling genes, as well as APX and SOD were studied (see below). As illustrated in Fig. 5A and B, the post-anoxic stress caused the AA levels to increase ∼8-fold at 3–6 h after re-exposure to air, suggesting an increased need for this antioxidant in order to compensate for the presumed increased amounts of ROS. However, a subsequent dramatic and continuous decrease in AA content was observed after 6 h and up to 48 h, suggesting the participation of ascorbate in the ROS scavenging activity. At the same time, AA in control mature green fruit markedly increased during the first hour and then declined before increasing again after 12 h. Regarding the expression profiles of the AA genes, it is intriguing to note that this stress triggered the induction of gene expression of all enzymes participating in AA biosynthesis (Fig. 6A). The transcript levels of most of the genes were evident after 3 h and peaked at 12 h upon re-exposure to air, coinciding with the elevated content of AA. Specifically, the steady-state level of GPI and PMM mRNAs peaked 12 h after re-exposure to air. Similarly, PMI transcript peaked at 12–24 h upon re-exposure to air. A peak at 12 h after exposure to air was also observed in the expression of GMP, GME, L-GalDH L-GalLDH, and AKR1 and 2. AKR38 was already highly expressed while in anoxia and remained unchanged up to 24 h in air, and then decreased. GPP transcript was present at low levels at 1 h and 3 h post-hypoxia, increased at 12 h, and peaked at 48 h after re-exposure to air. The level of these transcripts in the control group that was only exposed to air exhibited a rhythmicity during the time course of the experiment; expression was high at 0 h and dropped at 1 h, but was high again at 3 h and 6 h; expression was again low at 12 h and high at 24 h and 48 h. In fact, such rhythmicity is also seen in the expression of Arabidopsis GPP (unpublished microarray results available at Affymetrix online, experiment #149 conducted by Kieron Edwards and Andrew Millar). The Arabidopsis gene also showed sharp increases and declines within 6 h time frames. The transcripts of tomato GGP increased dramatically 3 h after transfer to air from the anoxia treatment. Expression levels dropped 24 h after transfer to air. The air controls exhibited a low steady-state level of expression which peaks at 1, 24, and 48 h after transfer to air, again indicating a rhythmic expression pattern for this gene. Transcripts showing homology with MIOX showed high accumulation of their mRNA after 48 h in anoxia, but decreased sharply as soon as the fruit were transferred back to air, and were almost undetectable after 12 h.

Bottom Line: L-ascorbate (the reduced form of vitamin C) participates in diverse biological processes including pathogen defence mechanisms, and the modulation of plant growth and morphology, and also acts as an enzyme cofactor and redox status indicator.Important aspects of the hypoxic and post-anoxic response in tomato fruit are discussed.The data suggest that L-galactose-1-phosphate phosphatase could play an important role in regulating ascorbic acid accumulation during tomato fruit development and ripening.

View Article: PubMed Central - PubMed

Affiliation: Group of Biotechnology of Pharmaceutical Plants, Division of Pharmacognosy-Pharmacology, Department of Pharmaceutical Sciences, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.

ABSTRACT
L-ascorbate (the reduced form of vitamin C) participates in diverse biological processes including pathogen defence mechanisms, and the modulation of plant growth and morphology, and also acts as an enzyme cofactor and redox status indicator. One of its chief biological functions is as an antioxidant. L-ascorbate intake has been implicated in the prevention/alleviation of varied human ailments and diseases including cancer. To study the regulation of accumulation of this important nutraceutical in fruit, the expression of 24 tomato (Solanum lycopersicon) genes involved in the biosynthesis, oxidation, and recycling of L-ascorbate during the development and ripening of fruit have been characterized. Taken together with L-ascorbate abundance data, the results show distinct changes in the expression profiles for these genes, implicating them in nodal regulatory roles during the process of L-ascorbate accumulation in tomato fruit. The expression of these genes was further studied in the context of abiotic and post-harvest stress, including the effects of heat, cold, wounding, oxygen supply, and ethylene. Important aspects of the hypoxic and post-anoxic response in tomato fruit are discussed. The data suggest that L-galactose-1-phosphate phosphatase could play an important role in regulating ascorbic acid accumulation during tomato fruit development and ripening.

Show MeSH
Related in: MedlinePlus