Tomato CRY1a plays a critical role in the regulation of phytohormone homeostasis, plant development, and carotenoid metabolism in fruits

Blue light photoreceptors, cryptochromes (CRYs), regulate multiple aspects of plant growth and development. However, our knowledge of CRYs is predominantly based on model plant Arabidopsis at early growth stage. In this study, we elucidated functions of CRY1a gene in mature tomato (Solanum lycopersicum) plants by using cry1a mutants and CRY1a-overexpressing lines (OE-CRY1a-1 and OE-CRY1a-2). In comparison with wild-type plants, cry1a mutants are relatively tall, accumulate low biomass, and bear more fruits, whereas OE-CRY1a plants are short stature, and they not only flower lately but also bear less fruits. RNA-seq, qRT-PCR, and LC-MS/MS analysis revealed that biosynthesis of gibberellin, cytokinin, and jasmonic acid was down-regulated by CRY1a. Furthermore, DNA replication was drastically inhibited in leaves of OE-CRY1a lines, but promoted in cry1a mutants with concomitant changes in the expression of cell cycle genes. However, CRY1a positively regulated levels of soluble sugars, phytofluene, phytoene, lycopene, and ss-carotene in the fruits. The results indicate the important role of CRY1a in plant growth and have implications for molecular interventions of CRY1a aimed at improving agronomic traits. The role of blue light signaling in plant growth and development remains unclear. Here, we report that CRY1a negatively regulates plant growth by inhibiting the biosynthesis of gibberellin and cytokinin, and the DNA replication, but positively regulates the accumulation of phytonutrients such as soluble sugars, phytofluene, phytoene, lycopene, and ss-carotene in the fruits. Therefore, CRY1a-mediated blue light signalingis actively involved in the regulation of plant growth, development, and metabolism in tomato.