Kinetic Modelling of Chloroplast Phototranslocations in Lemna trisulca L.: Two Rate Limiting Components?

An experimental model is derived from analytical action spectroscopy, in which total chloroplast translocation response to blue light is a linear combination of independent positive (low-intensity response) and negative (high-intensity response) components. This model explains transmission changes in Lemna trisulca L. leaves under steady-state light conditions and transient displacements after single pulses of strong blue light. itial rate of chloroplast phototranslocation as measured by the microphotometric method is dependent on the fluence rate of the actinic light in both positive and negative response ranges. In both cases the absolute level of response is proportional to the initial rate of chloroplast translocation. Model considerations and kinetic experiments indicate that positive and negative chloroplast responses to light are controlled by two different rate-limiting processes and consequently may have separate control mechanisms.