The response of embryo cells to Gibberellins is regulated by the Phytochrome in Datura ferox seeds.

ARANA MV; DE MIGUEL LC; AUGE GA; SÁNCHEZ RA

Brisbane

Workshop; 8th International workshop on seeds.; 2005

International Society for Seed Science

     In Datura ferox, promotion of germination by phytochrome (PHY) requires the novo gibberellin (GA) biosynthesis.  Our results show that exogenous GA promotion of germination (when GA synthesis is inhibited) is larger in R than in Far Red (FR)-treated seeds, demonstrating that a LFR of PHY controls the GA sensitivity.  The effect of R can be substituted by exogenous zeatin.  Formation of Pfr, the active form of PHY, enhances embryo growth potential (EGP). Inhibiting GA synthesis with paclobutrazol prevents the Pfr action, indicating the need of GA synthesis for EGP stimulus.  Pfr formation also enhances EGP response to GA, and exogenous zeatin promotes the embryo response to GA.  These results show that PHY modulates the sensitivity of germination and EGP to GA.   Cytokinins may be components of the light signal that modulate the sensitivity of seeds to GA.