Interactive Effects of Cytokinins, Light, and Sucrose on the Phenotypes and the Syntheses of Anthocyanins and Lignins in Cytokinin Overproducing Transgenic Arabidopsis

Sugar-Hormone Cross-Talk in Anthocyanin Biosynthesis

“…In Arabidopsis, CK is a positive regulator of the anthocyanin biosynthesis pathway and functions by modulating the expression of the anthocyanin biosynthesis genes PAL1, CHI, CHS and DFR (Deikman and Hammer, 1995). Transgenic plants overexpressing the isopentenyltransferase (IPT) gene, which is associated with CK biosynthesis, showed a greater accumulation of anthocyanin than wild-type plants in the presence of light and Suc (Guo et al, 2005). Interestingly, CK-and sugar-induced anthocyanin accumulation is strictly linked to light signaling pathways (Cominelli et al, 2008).…”

Cytokinins Enhance Sugar-Induced Anthocyanin Biosynthesis in Arabidopsis

“…CK stimulates photoreceptor-independent Suc signaling regulating anthocyanin pigmentation Irrespective of the presence of exogenous Suc, CK failed to induce anthocyanin accumulation in the dark (Argyros et al, 2008;Guo et al, 2005;Jeong et al, 2010), indicating that light is indispensable for CK activation of Suc signaling. As sugar signaling-dependent anthocyanin biosynthesis is under the control of light via photosynthesis-related factors (Das et al, 2011;Jeong et al, 2010), we assessed the effect of CK and sugar on known light signaling components to determine the point of convergence of the two signaling pathways.…”

“…CKs are also implicated in the regulation of anthocyanin accumulation presumably by affecting photosynthetic apparatus development or reactive oxygen species-mediated oxidative stress (Argyros et al, 2008) or by modulating sugar signaling (Guo et al, 2005). Thus, it is most likely that positive signaling pathways related to anthocyanin biosynthesis, such as those mediated by sugars, CK and light, are merged at a certain point of the synthesis pathway.…”

“…Cytokinis (CKs) are also implicated in the modulation of anthocyanin accumulation presumably via the regulation of the development of the photosynthetic apparatus, through reactive oxygen species-mediated oxidative stress (Argyros et al, 2008), or through the stimulation of Sucrose (Suc)-induced anthocyanin biosynthesis in the presence of light (Guo et al, 2005). In relation to anthocyanin biosynthesis, the CK receptors AHK2, 3, and 4 and the type-B response regulators ARR1, 10, and 12 were implicated in light-induced pigmentation in a redundant manner (Argyros et al, 2008).…”

“…Without light supplementation, other signals such as sucrose (Jeong et al, 2010), CK (Guo et al, 2005) and ethylene (Jeong et al, 2010) failed to induce anthocyanin pigmentation. Thus, it is most likely that signalings pathways leading to anthocyanin biosynthesis are merged at a certain point of the synthesis pathway.…”