Abstract

Photosynthesis is a promising target for optimisation to enhance biomass accumulation in plants. As the initial step in this complex process, light harvesting plays a pivotal role and depends on the prevailing light conditions.

While a minimum level of light intensity is required for the activation of photosynthetic electron transfer between photosystems, high light intensities can damage the photosynthetic machinery in the thylakoid membrane of chloroplasts by the formation of Reactive Oxygen Species (ROS), giving rise to photoinhibition.

This can be prevented by the action of several photoprotective mechanisms, including the dissipation of excess light energy as heat (non-photochemical quenching, NPQ ), and ROS scavenging. A specific group of carotenoids, the xanthophylls, are known to be involved in both mechanisms by binding to the subunits of the light harvesting complexes (LHCs) connected to the photosystems.

Under fluctuating light conditions, the rate of NPQ (de)activation is transiently limiting photosynthetic efficiency and can be accelerated by speeding up the xanthophyll cycle (Kromdijk et al., 2016). This, however, may in turn compromise the ROS scavenging capacity of xanthophylls and adversely affect plant growth.

Therefore, it is our objective to decouple both functions of xanthophylls in LHCs in plants to ultimately optimise plant growth without compromising ROS scavenging capacity.

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