Tesi etd-07312023-120147
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Tipo di tesi
Dottorato
Autore
MENCONI, JACOPO
URN
etd-07312023-120147
Titolo
From light and temperature to genomes: genetic regulation of anthocyanin biosynthesis in Solanum
lycopersicum fruit
Settore scientifico disciplinare
BIO/04
Corso di studi
Istituto di Scienze della Vita - PHD IN AGROBIOSCIENZE
Commissione
relatore Prof. PERATA, PIERDOMENICO
Parole chiave
- Anthocyanin
- BBX
- HY5
- light signaling
- MYB factors
- secondary metabolism
- Solanum lycopersicum
Data inizio appello
08/05/2024;
Disponibilità
parziale
Riassunto analitico
Anthocyanins, the polyphenolic pigments abundant in fruits and vegetables, offer a spectrum of health benefits and vibrant colours. These bioactive compounds have been proved to have cancer-fighting, immune-boosting, anti-inflammatory and cardiovascular health properties supporting overall health and well-being.
Tomato (Solanum lycopersicum) fruits are widely consumed worldwide for their nutritional value and versatile culinary applications. They are also appreciated for their health benefits, being rich sources of essential vitamins (e.g., vitamin C, vitamin A, and vitamin K), minerals (e.g., potassium and magnesium), and antioxidants (e.g., lycopene and beta-carotene). Polyphenolic compounds are present only in the peel, but they do not include anthocyanins. Tomato indeed can synthetize anthocyanins only in the vegetative parts of the plant but not in the fruit, where the red colour is due to lycopene. In the last years different attempts were made to obtain anthocyanin-rich tomatoes, ranging from heterologous expression of transcription factors to conventional breeding.
By gaining deeper insights into the molecular mechanisms underlying anthocyanin synthesis in tomato, researchers can further enhance the nutritional content and visual appeal of this beloved fruit, ultimately promoting a healthier and more enjoyable diet for consumers.
The breeding approach led to the development of many lines of purple tomatoes by reintroducing in the genome alleles from wild relative of Solanum lycopersicum, able to establish the synthesis of anthocyanins in the fruit. Unfortunately, all these lines can synthetize anthocyanins only in the fruit epicarp, with the flesh remaining red. Furthermore, they accumulate such pigments only in response to high light with the quantity of anthocyanins tightly correlated also with temperature. In fact, high temperatures repress the ability to synthetize anthocyanins, while low temperatures derepress the pathway.
The first work package of the PhD research project investigates the molecular basis of anthocyanin production in the tomato line 'Aubergine' (Abg). The study identifies the AN2like gene as a critical regulator of anthocyanin synthesis in Abg fruits, revealing a novel regulation mechanism through alternative splicing. Understanding the genetic basis of anthocyanin synthesis in Abg paves the way for potential breeding strategies to enhance the nutritional content and colour vibrancy of tomatoes.
The second work package delves into the regulatory landscape of anthocyanin biosynthesis in the purple tomato variety 'SunBlack' (SB) in response to light. The study identifies SlBBX20 and SlBBX21 as crucial players in light-induced anthocyanin synthesis, demonstrating their physical interactions with central regulators of the pathway. Understanding the complex interplay of these regulators offers insights into enhancing anthocyanin content in tomatoes under non-optimal light conditions.
The third work package finally unravels the intriguing relationships between light and temperature signalling in anthocyanin synthesis during tomato fruit development. SB tomatoes exhibit temperature-sensitive pigmentation, leading to varying anthocyanin accumulation. The roles of COP1 and HY5 in this process are explored, leading at the final hypothesis that elevated temperatures may hinder anthocyanin production through increased COP1 levels. COP1 under light conditions is normally relocated from the nucleus to the cytoplasm allowing the accumulation of its target HY5 into the nucleus. HY5 then activates the expression of many target genes, including anthocyanins related genes. Here we show that high temperatures, even under high light conditions, relocate COP1 into the nucleus thus allowing degradation of HY5 and repression of anthocyanin synthesis. This understanding allows for the optimization of temperature conditions during tomato cultivation to maximize the health-promoting anthocyanin content.
Tomato (Solanum lycopersicum) fruits are widely consumed worldwide for their nutritional value and versatile culinary applications. They are also appreciated for their health benefits, being rich sources of essential vitamins (e.g., vitamin C, vitamin A, and vitamin K), minerals (e.g., potassium and magnesium), and antioxidants (e.g., lycopene and beta-carotene). Polyphenolic compounds are present only in the peel, but they do not include anthocyanins. Tomato indeed can synthetize anthocyanins only in the vegetative parts of the plant but not in the fruit, where the red colour is due to lycopene. In the last years different attempts were made to obtain anthocyanin-rich tomatoes, ranging from heterologous expression of transcription factors to conventional breeding.
By gaining deeper insights into the molecular mechanisms underlying anthocyanin synthesis in tomato, researchers can further enhance the nutritional content and visual appeal of this beloved fruit, ultimately promoting a healthier and more enjoyable diet for consumers.
The breeding approach led to the development of many lines of purple tomatoes by reintroducing in the genome alleles from wild relative of Solanum lycopersicum, able to establish the synthesis of anthocyanins in the fruit. Unfortunately, all these lines can synthetize anthocyanins only in the fruit epicarp, with the flesh remaining red. Furthermore, they accumulate such pigments only in response to high light with the quantity of anthocyanins tightly correlated also with temperature. In fact, high temperatures repress the ability to synthetize anthocyanins, while low temperatures derepress the pathway.
The first work package of the PhD research project investigates the molecular basis of anthocyanin production in the tomato line 'Aubergine' (Abg). The study identifies the AN2like gene as a critical regulator of anthocyanin synthesis in Abg fruits, revealing a novel regulation mechanism through alternative splicing. Understanding the genetic basis of anthocyanin synthesis in Abg paves the way for potential breeding strategies to enhance the nutritional content and colour vibrancy of tomatoes.
The second work package delves into the regulatory landscape of anthocyanin biosynthesis in the purple tomato variety 'SunBlack' (SB) in response to light. The study identifies SlBBX20 and SlBBX21 as crucial players in light-induced anthocyanin synthesis, demonstrating their physical interactions with central regulators of the pathway. Understanding the complex interplay of these regulators offers insights into enhancing anthocyanin content in tomatoes under non-optimal light conditions.
The third work package finally unravels the intriguing relationships between light and temperature signalling in anthocyanin synthesis during tomato fruit development. SB tomatoes exhibit temperature-sensitive pigmentation, leading to varying anthocyanin accumulation. The roles of COP1 and HY5 in this process are explored, leading at the final hypothesis that elevated temperatures may hinder anthocyanin production through increased COP1 levels. COP1 under light conditions is normally relocated from the nucleus to the cytoplasm allowing the accumulation of its target HY5 into the nucleus. HY5 then activates the expression of many target genes, including anthocyanins related genes. Here we show that high temperatures, even under high light conditions, relocate COP1 into the nucleus thus allowing degradation of HY5 and repression of anthocyanin synthesis. This understanding allows for the optimization of temperature conditions during tomato cultivation to maximize the health-promoting anthocyanin content.
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