Tomato plants overexpressing cryptochrome 2 reveal altered expression of energy and stress‐related gene products in response to diurnal cues

Abstract

In order to sense and respond to the fluctuating light conditions, higher plants possess several families of photoreceptors, such as phytochromes (PHYs), cryptochromes (CRYs) and phototropins. CRYs are responsible for photomorphogenesis and play a role in circadian, developmental and adaptive growth regulation of plants. In tomato (Solanum lycopersicum), CRY2 controls vegetative development, flowering time, fruit antioxidant content as well as the diurnal transcription of several other photoreceptor genes. We applied large-scale molecular approaches to identify altered transcripts and proteins in tomato wild-type (WT) versus a CRY2 overexpressing transgenic genotype, under a diurnal rhythm. Our results showed that tomato CRY2 profoundly affects both gene and protein expression in response to daily light cycle. Particularly altered molecular pathways are related to biotic/abiotic stress, photosynthesis, including components of the light and dark reactions and of starch and sucrose biosynthesis, as well as to secondary metabolism, such as phenylpropanoid, phenolic and flavonoid/anthocyanin biosynthesis pathways. One of the most interesting results is the coordinated up-regulation, in the transgenic genotype, of a consistent number of transcripts and proteins involved in photorespiration and photosynthesis. It is conceivable that light modulates the energetic metabolism of tomato through a fine CRY2-mediated transcriptional control.

A proteome map of a quadruple photoreceptor mutant sustains its severe photosynthetic deficient phenotype

“…Protein profiles have also been investigated in cry1, cry1 cry2 and phyA phyB mutants in Arabidopsis (Phee et al, 2007;Yang et al, 2008;Xu et al, 2009) and cry2 overexpressors in tomato (Lopez et al, 2012). These studies show that light perception through photoreceptors primarily altered photosynthetic and metabolic proteins.…”

Algal photoreceptors: in vivo functions and potential applications

“…Somatic cells have a much lower photosynthetic capacity than reproductive cells (Choi et al 1996) and undergo programmed cell death at the end of their lifespan Kochert 1981a, b, 1982). In plants, cryptochromes are also involved in the light-dependent gene expression; the light dependence mainly affects genes involved in the response to biotic/abiotic stress and the regulation of photosynthesis (Danon et al 2006;Lopez et al 2011). The stronger expression of VcCRYp in somatic cells compared to reproductive cells suggests that this cryptochrome is an upstream or downstream regulatory component in cell type-specific regulation of photosynthesis and/or programmed cell death.…”

A reverse genetics approach identifies novel mutants in light responses and anthocyanin metabolism in petunia

“…Petunia transcriptome exhibits high sequence and functional conservation to tomato transcript profiles (Rensink et al 2005) and, in this species deetiolation and anthocyanin biosynthesis are mainly controlled by phyA-and cry1-mediated signaling (Weller et al 2001). However, the overexpression of CRY2 has also led to enhanced anthocyanin accumulation in tomato fruits (Giliberto et al 2005;Lopez et al 2012). Petunia PHY and CRY transcripts share extensive sequence conservation to the (Table S1).…”

“…The activity of anthocyanin biosynthetic genes is largely regulated at the transcriptional level via the function of several classes of transcriptional regulators, such as: WD40, helix-loop-helix (HLH), R2R3 and R3 MYB, WRYK, Zn finger and MADSbox (Koes et al 2005;Ambawat et al 2013). In several plant species, light has been demonstrated to be an important environmental factor controlling anthocyanin accumulation, directly via transcriptional control of biosynthetic genes and transcription factors or indirectly via developmental regulation (Albert et al 2009;Lopez et al 2012;Petroni and Tonelli 2011;Huang et al 2012;Ambawat et al 2013).…”