Overexpression of homologous phytochrome genes in tomato: exploring the limits in photoperception

摘要: Transgenic tomato [Lycopersicon esculentum (=Solanum lycopersicum)] lines overexpressing PHYA, PHYB1, or PHYB2, under control of the constitutive double-35S promoter from cauliflower mosaic virus (CaMV) have been generated to test level saturation in individual phytochrome-signalling pathways tomato. Western blot analysis confirmed elevated phytochrome protein levels dark-grown seedlings respective PHY (PHYOE) lines. Exposure 4 h red light resulted a decrease A PHYAOE lines, indicating that chromophore availability is not limiting for assembly into holoprotein and excess also targeted light-regulated destruction. The elongation anthocyanin accumulation responses plants grown white light, far-red end-of-day were used characterization selected PHYOE In addition, response different fluence rates 4-d-old was studied. phyA had little effect on seedling adult plant phenotype. Both mutant background PHYB2OE double-mutant rescued phenotype, proving expression transgene results biologically active phytochrome. PHYB1OE showed mild effects inhibition stem no high irradiance response. By contrast, strong elongation, enhancement accumulation, amplification