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Agronomic performance and transcriptional analysis of carotenoid biosynthesis in fruits of transgenic HighCaro and control tomato lines under field conditions.

Giorio G, Stigliani AL, D'Ambrosio C - Transgenic Res. (2006)

Bottom Line: One of the most significant achievements was "HighCaro (HC)," a transgenic tomato plant constitutively expressing the tomato lycopene beta-cyclase (tLcy-b), that produces orange fruits due to the complete conversion of lycopene to beta-carotene.Unexpectedly, Lcy-b expression in transgenic fruits was also developmentally regulated, despite the fact that the gene was driven by a constitutive promoter.Our data provide evidence that in photosynthetic cells a strict and aspecific mechanism controls the level of transcripts until the onset of chromoplasts differentiation, at which point a gene-specific control on transcription takes place.

View Article: PubMed Central - PubMed

Affiliation: Metapontum Agrobios, S.S. Jonica 106, Km 448.2, Metaponto, MT , 75010, Italy. ggiorio@agrobios.it

ABSTRACT
Genetic manipulation of carotenoid biosynthesis in higher plants has been the objective of a number of biotechnology programs, e.g. the Golden Rice Program. However, tomato (Solanum lycopersicum L.), which naturally accumulates lycopene in fruits, has attracted the attention of many groups who have manipulated it to increase or diversify carotenoid accumulation. One of the most significant achievements was "HighCaro (HC)," a transgenic tomato plant constitutively expressing the tomato lycopene beta-cyclase (tLcy-b), that produces orange fruits due to the complete conversion of lycopene to beta-carotene. In this article we report the results of a field trial conducted in Metaponto (Italy) on HC and on two control genotypes to evaluate the stability of the transgenic trait and their yield performances. Transcriptional regulation of eight genes involved in carotenogenesis was assayed by quantitative real-time PCR (qRT-PCR) analysis on fruits collected at four distinct development stages. Statistical analysis results demonstrated that in field conditions the transgene maintained its ability to induce the conversion of lycopene to beta-carotene. Moreover, agronomic performances and fruit quality in the transgenic line were not impaired by this metabolic disturbance. Results of qRT-PCR analysis suggested that transcription of PSY-1, PDS and ZDS genes were developmentally regulated in both genotypes. Unexpectedly, Lcy-b expression in transgenic fruits was also developmentally regulated, despite the fact that the gene was driven by a constitutive promoter. Our data provide evidence that in photosynthetic cells a strict and aspecific mechanism controls the level of transcripts until the onset of chromoplasts differentiation, at which point a gene-specific control on transcription takes place.

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Real-time PCR analysis of transcript contents of the eight carotenoid genes in leaf RNA of transgenic (HighCaro) and control (Red Setter) lines. An asterisk indicates that the difference between the means of the two genotypes was statistically significant (Student’s t-test; α = 0.05)
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Fig4: Real-time PCR analysis of transcript contents of the eight carotenoid genes in leaf RNA of transgenic (HighCaro) and control (Red Setter) lines. An asterisk indicates that the difference between the means of the two genotypes was statistically significant (Student’s t-test; α = 0.05)

Mentions: Transcription patterns of the eight genes involved in carotenoid biosynthesis during maturation of RS and HC fruits are shown in Fig. 3aFig. 3a, Fig. 3b. Estimated transcript levels in leaf RNA are presented in Fig. 4.


Agronomic performance and transcriptional analysis of carotenoid biosynthesis in fruits of transgenic HighCaro and control tomato lines under field conditions.

Giorio G, Stigliani AL, D'Ambrosio C - Transgenic Res. (2006)

Real-time PCR analysis of transcript contents of the eight carotenoid genes in leaf RNA of transgenic (HighCaro) and control (Red Setter) lines. An asterisk indicates that the difference between the means of the two genotypes was statistically significant (Student’s t-test; α = 0.05)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2734263&req=5

Fig4: Real-time PCR analysis of transcript contents of the eight carotenoid genes in leaf RNA of transgenic (HighCaro) and control (Red Setter) lines. An asterisk indicates that the difference between the means of the two genotypes was statistically significant (Student’s t-test; α = 0.05)
Mentions: Transcription patterns of the eight genes involved in carotenoid biosynthesis during maturation of RS and HC fruits are shown in Fig. 3aFig. 3a, Fig. 3b. Estimated transcript levels in leaf RNA are presented in Fig. 4.

Bottom Line: One of the most significant achievements was "HighCaro (HC)," a transgenic tomato plant constitutively expressing the tomato lycopene beta-cyclase (tLcy-b), that produces orange fruits due to the complete conversion of lycopene to beta-carotene.Unexpectedly, Lcy-b expression in transgenic fruits was also developmentally regulated, despite the fact that the gene was driven by a constitutive promoter.Our data provide evidence that in photosynthetic cells a strict and aspecific mechanism controls the level of transcripts until the onset of chromoplasts differentiation, at which point a gene-specific control on transcription takes place.

View Article: PubMed Central - PubMed

Affiliation: Metapontum Agrobios, S.S. Jonica 106, Km 448.2, Metaponto, MT , 75010, Italy. ggiorio@agrobios.it

ABSTRACT
Genetic manipulation of carotenoid biosynthesis in higher plants has been the objective of a number of biotechnology programs, e.g. the Golden Rice Program. However, tomato (Solanum lycopersicum L.), which naturally accumulates lycopene in fruits, has attracted the attention of many groups who have manipulated it to increase or diversify carotenoid accumulation. One of the most significant achievements was "HighCaro (HC)," a transgenic tomato plant constitutively expressing the tomato lycopene beta-cyclase (tLcy-b), that produces orange fruits due to the complete conversion of lycopene to beta-carotene. In this article we report the results of a field trial conducted in Metaponto (Italy) on HC and on two control genotypes to evaluate the stability of the transgenic trait and their yield performances. Transcriptional regulation of eight genes involved in carotenogenesis was assayed by quantitative real-time PCR (qRT-PCR) analysis on fruits collected at four distinct development stages. Statistical analysis results demonstrated that in field conditions the transgene maintained its ability to induce the conversion of lycopene to beta-carotene. Moreover, agronomic performances and fruit quality in the transgenic line were not impaired by this metabolic disturbance. Results of qRT-PCR analysis suggested that transcription of PSY-1, PDS and ZDS genes were developmentally regulated in both genotypes. Unexpectedly, Lcy-b expression in transgenic fruits was also developmentally regulated, despite the fact that the gene was driven by a constitutive promoter. Our data provide evidence that in photosynthetic cells a strict and aspecific mechanism controls the level of transcripts until the onset of chromoplasts differentiation, at which point a gene-specific control on transcription takes place.

Show MeSH
Related in: MedlinePlus