Utilization of the Genetic Resources of Wild Species To Create a Nontransgenic High Flavonoid Tomato

Abstract

Flavonoids represent a large and important group of plant natural products that are ubiquitous in the plant kingdom. Epidemiological studies have shown the health benefits of a diet high in flavonoids. However, the dietary intake of flavonoids in most western populations is limited, creating a need to find alternative food sources for these polyphenolic secondary metabolites. The domestication of many of our cultivated food crops has resulted in alterations in the biosynthetic pathways of many essential micronutrients and vitamins through inadvertent counterselection against nutritional traits in favor of agronomic ones. Flavonoids are nearly absent from fruits of cultivated tomato (Lycopersicon esculentum Mill.), a major vegetable in human diets. Previous attempts to restore the flavonoid pathway in tomato fruits have been limited to transgenic strategies, suggesting that the problem was intractable through traditional methods. Here, we describe for the first time a nontransgenic metabolic engineering approach to developing a high flavonoid tomato using a wild tomato species (Lycopersicon pennelliiv. puberulum) and demonstrate the opportunities for restoring functional pathways using the genetic resources of wild species, resulting in production of healthier foods.

Flavonoid Profiling and Biosynthetic Gene Expression in Flesh and Peel of Two Tomato Genotypes Grown under UV-B-Depleted Conditions during Ripening

“…Other authors proposed a nontransgenic approach using traditional breeding with a wild tomato species, which expresses all flavonoid structural genes, including CHI, in both peel and fruit flesh (20).…”

Ascorbic Acid Distribution in Three Introgression Lines of Tomato

“…Many researches have been conducted to improve antioxidant content in tomato fruit through genetic engineering and breeding schemes (Willits et al 2005, Butelli et al 2008, Sapir et al 2008. Because the breeding schemes often require considerable investments to select and characterize genetic resources, the use of available genetic stocks, such as introgression line populations, is advantageous.…”

Metodologías para la evaluación del contenido en polifenoles en tomate aplicadas al estudio del efecto del genotipo y de estrategias de cultivo respetuosas con el medio ambiente

“…Ballester et al [152] suggested that upon ripening an increase in the expression CHS expression and a coordinated decrease in the expression of CHI would result in the accumulation of naringenin chalcone and in a l i mi tati on of flavonol contents. Previously, Willits et al [153] suggested that the lack of expression of CHI in the peel of the fruit, probably caused by a mutation in a fruit specific promoter would explain the high levels of naringenin chalcone in this tissue. The authors also assumed that cultivated tomato would have lost the expression of CHI in the peel in an early step of the domestication process.…”

“…Durante la maduración del tomate, se produce un aumento en la expresión del enzima CHS junto con la desregulación de CHI en la piel del fruto produce una acumulación de naringenin chalcona y limita la acumulación de naringenina (Ballester et al, 2010). Willits et al (2005) sugirió que los altos niveles de naringenin chal cona en la piel del fruto podrían explicarse por la falta de expresión de CHI en este tejido. Además, estos autores también sugieren que es posible que el tomate cultivado haya perdido la expresión de CHI en la piel en un paso temprano del proceso de domesticación.…”

“…esta aproximación, se ha conseguido aumentar el contenido en flavonoides del tomate usando especies silvestres como Solanum pennellii Correl, de frutos verdes y pequeños, para restaurar la ruta de los flavonoides en la pulpa del fruto. Mediante el cruzamiento y selección por la expresión de CHI en la pulpa, se ha llegado a desarrollar nuevas variedades hibridas con especies cultivadas con mayores acumulaciones de diglicósido de quercetina (Willits et al, 2005).…”