Daucus carota as a novel model to evaluate the effect of light on carotenogenic gene expression

Abstract

Carotenoids are synthesized in prokaryotic and eukaryotic organisms. In plants and algae, these lipophilic molecules possess antioxidant properties acting as reactive oxygen species scavengers and exert functional roles in hormone synthesis, photosynthesis, photomorphogenesis and in photoprotection. During the past decade almost all carotenogenic genes have been identified as a result of molecular, genetic and biochemical approaches utilizing Arabidopsis thaliana as the model system. Studies carried out in leaves and fruits of A. thaliana and tomato determined that light regulates carotenoid biosynthesis preferentially through the modulation of carotenogenic gene transcription. In this work we showed for the first time that light induces accumulation of psy1, pds and zds2 transcripts in leaves of Daucus carota (carrot), a novel plant model. In addition, modified roots of carrots exposed to light accumulate zds1, whereas the pds gene is highly repressed, suggesting that some carotenogenic genes, which are expressed in roots, are regulated by light. Additionally, light negatively regulates the development of the modified carrot root in a reversible manner. Therefore, this suggests that light affects normal growth and carotenogenic gene expression in the modified root of carrot plants. The molecular insight gained into the light-regulated expression of carotenoid genes in this and other model systems will facilitate our understanding of the regulation of carotenoid biosynthesis to improve the prospects for the metabolic engineering of carotenoid production in plants.

Carotenoids and Photosynthesis - Regulation of Carotenoid Biosyntesis by Photoreceptors

“…When roots were exposed to light, they did not develop normally and the expression of almost all genes differs from the pattern obtained in dark-grown roots during development ( Figure 3A). In addition, the roots developed in the presence of light have the same carotenoid composition and amount as in leaves (Stange et al, 2008;Fuentes et al, 2011 in preparation). The thin non-orange carrot root also accumulates chloroplasts instead of chromoplasts, as leaves, and the carotenoid gene expression profile is almost the same as those expressed in the photosynthetic organ.…”

“…Therefore, light alters the morphology and development of carrot modified roots in a reversible manner (Stange et al, 2008). Light inhibited storage root development, possibly because some transcriptional or growth factors are repressed, although more extensive studies are needed to investigate this phenomenon.…”

“…B; changes in the phenotype of a 8 weeks old carrot root grown in light (R/L) and then transferred to dark conditions (R/D) until 12 weeks and 24 weeks. The root normal development is inhibited by light in a reversible manner (Modified from Stange et al, 2008).…”

In silico identification and analysis of phytoene synthase genes in plants

“…In the plants studied, the PSY genes not only showed diversity in gene evolution and structure, but also tissue-specific expression and function evolution in different plants (Giorio et al, 2008;Stange et al, 2008;Arango et al, 2010;Fuentes et al, 2012). In the present study, we comprehensively analyzed the PSY gene family in plants on the entire genome level.…”

Rapid Detection of Heavy Metals with the Response of Carotenoids in Daucus Carota

“…The culture of taproot cell was conducted in dark condition, in order to promote the synthesis of carotenoids, on the other hand inhibiting the synthesis of chlorophylls [25], [26].…”