Milan: Protein optimises photosynthesis and productivity in plants

Research lead

Collaborating scientists at the University of Milan, University of Piemonte Orientale and the Ludwig Maximilian Universitaet, Munich, have identified a plant protein they say is responsible for optimise light absorption during photosynthesis, by adapting the photosynthetic apparatus to changes of environmental light conditions.

This finding could be applied to improve plant productivity and has relevance to research in capturing solar radiation as a renewable energy source.

While plants are able to convert light energy into organic compounds through photosynthesis, the solar radiation absorbed by leaves is subjected to continuous changes in intensity and spectral composition due to a wide range of factors, including clouds, movements of leaves in a breeze or wind, and the day/night cycle.

To cope with these light changes and optimise photosynthetic performance, plants have developed molecular mechanisms that allow a very rapid adaptation of the photosynthetic apparatus to the different environmental light conditions.

Several reports have shown that the photosynthetic apparatus can switch from two different functional conformations, named “state 1” and “state 2”, in response to environmental light conditions. In 2005, the kinase enzyme, STN7, was identified as being responsible for the photosynthetic transition from “state 1” to “state 2”. STN7 adds a phosphate group to a protein of the photosynthetic apparatus involved in light absorption.

In this latest study the researchers have identified the enzyme phosphatise, or TAP38, as responsible for removing the phosphate group from a protein of the photosynthetic apparatus, thus inducing the transition from “state 2” to “state 1”.

The gene encoding TAP38 has been isolated in the model plant species Arabidopsis thaliana through a functional genomics approach. In particular, ten nuclear genes, encoding phosphatises, either predicted or experimentally verified to be located in the chloroplast, have been knocked out and the corresponding Arabidopsis mutants tested for their capability to perform state transitions.

The researchers say that besides clarifying important molecular aspects of photosynthesis regulation, the work sheds new light on photosynthesis and agricultural productivity improvement. Moreover, since leaves can be considered very similar to solar panels, knowing how plants optimise light capture might help in the development of more efficient technologies for absorbing and accumulating the solar radiation.