Antagonistic effect of indole-3-acetic acid on kinetin-stimulated amaranthin accumulation in the cotyledons of Amaranthus mangostanus seedlings

Light triggered the initiation of amaranthin biosynthesis in cotyledons of Amaranthus mangostanus L. seedlings. Cytokinin induced amaranthin synthesis in the dark and increased the accumulation of amaranthin under light irradiation. No studies have explored whether indole-3-acetic acid (IAA) can affect kinetin-induced amaranthin accumulation in seedlings of A. mangostanus L. In this study, we found that IAA inhibited both the kinetin- and light-induced synthesis of amaranthin. In the dark, 10.0 mg l^?1 IAA caused a 68% reduction in amaranthin production after induction by 5.0 mg l^?1 kinetin. In the presence of light, 10.0 mg l^?1 IAA resulted in a 50% decrease in amaranthin synthesis following induction by 5.0 mg l^?1 kinetin. In addition, IAA could reverse kinetin-induced amaranthin accumulation under red, blue, or far-red light conditions. Our results suggest that IAA had an antagonistic effect on the light-induced or cytokinin-stimulated accumulation of amaranthin in the cotyledons of A. mangostanus L. seedlings.