Manipulation of light signal transduction as a means of modifying fruit nutritional quality in tomato

Abstract

Fruit constitutes a major component of human diets, providing fiber, vitamins, and phytonutrients. Carotenoids are a major class of compounds found in many fruits, providing nutritional benefits as precursors to essential vitamins and as antioxidants. Although recent gene isolation efforts and metabolic engineering have primarily targeted genes involved in carotenoid biosynthesis, factors that regulate flux through the carotenoid pathway remain largely unknown. Characterization of the tomato high-pigment mutations (hp1 and hp2) suggests the manipulation of light signal transduction machinery may be an effective approach toward practical manipulation of plant carotenoids. We demonstrate here that hp1 alleles represent mutations in a tomato UV-DAMAGED DNA-BINDING PROTEIN 1 (DDB1) homolog. We further demonstrate that two tomato light signal transduction genes, LeHY5 and LeCOP1LIKE, are positive and negative regulators of fruit pigmentation, respectively. Down-regulated LeHY5 plants exhibit defects in light responses, including inhibited seedling photomorphogenesis, loss of thylakoid organization, and reduced carotenoid accumulation. In contrast, repression of LeCOP1LIKE expression results in plants with exaggerated photomorphogenesis, dark green leaves, and elevated fruit carotenoid levels. These results suggest genes encoding components of light signal transduction machinery also influence fruit pigmentation and represent genetic tools for manipulation of fruit quality and nutritional value.

Changes of some anti-oxidative physiological indices under soil water deficits among 10 wheat (Triticum aestivum L.) genotypes at tillering stage

“…Unraveling the physiological and molecular basis for the plasticity of plant defending metabolism not only provides access to a largely untapped resource of genes and selection markers for breeding enhanced stress tolerance in crops but also ensures improved food security world-wide [64,23,16,12 Living organisms can be viewed as reducing-oxidising (redox) systems in which catabolic, largely oxidative processes produce energy and anabolic, principally reductive processes assimilate it [13,27,28,47]. Aerobic organisms exploit the redox potential of oxygen while controlling oxidation.…”

“…Just 2 years ago, European Commission, who once kept conservative to biotechnological breeding, constructed a big project: Plants for the Future in which much is involved in resistance drought [5]. Many advances in relation to this hot topic, including molecular mechanism of antidrought and corresponding molecular breeding have taken place [4,10,16,17,21,[23][24][25]30,31,35,37,39,42,48,[55][56][57][58][59]. Although the obtained transgenic crops (mainly, wheat) by different types of gene technology all exhibit resistance drought to some extent, they have many shortfalls related to agronomical performance and/or development [1,16,17,21,24,30,39,49,56].…”

Características fisiológicas de microtomateiros fitocromo-mutantes

“…É possível que a baixa intensidade de radiação das condições do experimento tenha influenciado o baixo conteúdo de carotenóides relativo ao de clorofila no mutante atv, no sentido do não requerimento de um forte aparato contra danos fotooxidativos pelas plantas. O maior conteúdo de carotenóides totais observado no mutante hp1, em relação aos demais microtomateiros estudados, é um comportamento similar àquele encontrado em frutos de tomateiro desse mesmo mutante, quando comparados aos das plantas selvagens (LIU et al, 2004).…”

Gr and hp-1 tomato mutants unveil unprecedented interactions between arbuscular mycorrhizal symbiosis and fruit ripening

“…Gr is deficient in fruit ET perception and high-pigment-1 (hp-1), displays enhanced light signal perception throughout the plant, including the fruit. In addition, both of them have been well characterized (Liu et al 2004;Barry and Giovannoni 2006) and are used also for commercial purposes. Both mutants showed similar AM colonization levels in roots (Fig.…”

“…As a further step, we selected two of them: Green ripe (Gr) which possesses a fruitspecific deficiency in ET perception (Barry and Giovannoni 2006), and high pigment 1 (hp-1) which presents a tomato UV-DAMAGED DNA-BINDING PROTEIN-1 (DDB1) gene mutation. This mutation results in constitutive light signal transduction that affects all plant organs and leads to elevated green fruit chlorophyll and ripe fruit carotenoid accumulation (Liu et al 2004). These two mutants were investigated by applying molecular and biochemical approaches to compare the effect of AM symbiosis in roots versus fruits.…”