Fruit-Localized Phytochromes Regulate Lycopene Accumulation Independently of Ethylene Production in Tomato

Abstract

We show that phytochromes modulate differentially various facets of light-induced ripening of tomato fruit (Solanum lycopersicum L.). Northern analysis demonstrated that phytochrome A mRNA in fruit accumulates 11.4-fold during ripening. Spectroradiometric measurement of pericarp tissues revealed that the red to far-red ratio increases 4-fold in pericarp tissues during ripening from the immature-green to the red-ripe stage. Brief red-light treatment of harvested mature-green fruit stimulated lycopene accumulation 2.3-fold during fruit development. This red-light-induced lycopene accumulation was reversed by subsequent treatment with far-red light, establishing that light-induced accumulation of lycopene in tomato is regulated by fruit-localized phytochromes. Red-light and red-light/far-red-light treatments during ripening did not influence ethylene production, indicating that the biosynthesis of this ripening hormone in these tissues is not regulated by fruit-localized phytochromes. Compression analysis of fruit treated with red light or red/far-red light indicated that phytochromes do not regulate the rate or extent of pericarp softening during ripening. Moreover, treatments with red or red/far-red light did not alter the concentrations of citrate, malate, fructose, glucose, or sucrose in fruit. These results are consistent with two conclusions: (a) fruit-localized phytochromes regulate light-induced lycopene accumulation independently of ethylene biosynthesis; and (b) fruit-localized phytochromes are not global regulators of ripening, but instead regulate one or more specific components of this developmental process.

Direct regulation of phytoene synthase gene expression and carotenoid biosynthesis by phytochrome-interacting factors

“…The involvement of phytochromes in the control of carotenoid accumulation and PSY gene expression in different plant species, including tomato, maize, and rice (12,13,33), along with the presence of G-boxes in the promoters of light-responsive maize and rice PSY genes (13,34), suggest that the participation of PIFs in the light-mediated regulation of PSY gene expression might be a general mechanism in plants.…”

Effect of coloured shade nets on some nutritional characteristics of a kapia type pepper grown in plastic tunnel

“…3, No. 2 (2016) fruit-localized phytochromes, sensitive to R/ FR ratio, mediate lycopene accumulation in the berries (Alba et al 2000). Sampling time had a highly significant effect on the carotenoid content.…”

Carotenoid Biosynthesis Regulatory Mechanisms in Plants

“…High temperatures 32 and excessive light intensity were found to affect lycopene synthesis and degradation in tomato and grapefruit 26 29 . Alba et al 30 found that red light will stimulate carotenoid accumulation in tomato, whereas far-red light blocks its accumulation. In contrast, Vogele 31 observed that lycopene synthesis in watermelon is not affected by temperatures in the range of 20 to 37 , but its content is reduced at temperatures between 4 and 21 in red grapefruit 32,33 .…”