Harvesting Far-Red Light with Plant Antenna Complexes Incorporating Chlorophyll d

Abstract

Increasing the absorption cross section of plants by introducing far-red absorbing chlorophylls (Chls) has been proposed as a strategy to boost crop yields. To make this strategy effective, these Chls should bind to the photosynthetic complexes without altering their functional architecture. To investigate if plant-specific antenna complexes can provide the protein scaffold to accommodate these Chls, we have reconstituted the main light-harvesting complex (LHC) of plants LHCII in vitro and in silico , with Chl d . The results demonstrate that LHCII can bind Chl d in a number of binding sites, shifting the maximum absorption ∼25 nm toward the red with respect to the wild-type complex (LHCII with Chl a and b ) while maintaining the native LHC architecture. Ultrafast spectroscopic measurements show that the complex is functional in light harvesting and excitation energy transfer. Overall, we here demonstrate that it is possible to obtain plant LHCs with enhanced far-red absorption and intact functional properties.

Here comes the sun: How optimization of photosynthetic light reactions can boost crop yields

“…These red‐shifted chlorophylls d and f with absorption maxima at 740 and 760 nm, respectively, have been discovered in certain cyanobacterial species (Li and Chen, 2015). The novel chlorophyll d is predicted to be able to bind to LHC proteins, expanding the range of light absorption of chlorophyll a beyond 700 nm into the far‐red region, which is often found in the lower canopy of plants and could therefore enhance light harvesting and boost crop yields (Elias et al, 2021). Cyanobacterial OCP, on the other hand, absorbs wavelengths in the blue–green region and is attached to the light‐harvesting antennae (phycobilisomes), where it is responsible for photoprotective dissipation of excess light energy as heat (NPQ) and scavenging of ROS (Muzzopappa and Kirilovsky, 2020).…”

A paler shade of green: engineering cellular chlorophyll content to enhance photosynthesis in crowded environments

“…This ambitious strategy originated with the discovery of red‐shifted cyanobacterial Chl d (Miyashita et al ., 1996) and f types (Nürnberg et al ., 2018), the latter being characterized in terms of its biosynthetic pathway (Trinugroho et al ., 2020). The idea of expressing red‐shifted Chls in the understory leaves of the canopy as a way of increasing light‐harvesting capacity has recently attracted attention based on in vitro evidence that plant Lhc can bind these chromophores (Elias et al ., 2021) in a stable manner and maintain functional excitation energy transfer. However, this approach is complicated by at least three major issues: the enzyme(s) responsible for the synthesis of Chl d has yet to be elucidated; the biosynthesis of the heterologous pigment(s) must be implemented in the plant; and the ability to absorb low‐energy far‐red photons could slow down energy trapping, especially in PSII RCs, ultimately reducing LUE (Mascoli et al ., 2020).…”

Enhancing the spectral range of plant and bacterial Light-Harvesting pigment-protein complexes with various synthetic chromophores incorporated into lipid vesicles

“…Such modularity may be more difficult to generate with alternative approaches employing covalent crosslinking of a dye directly to the LH protein complex [21][22][23][24]61]. Other studies have shown that non-native chromophores may be non-covalently incorporated into the natural pigment binding sites of LH complexes [62][63][64] by reconstituting the apoprotein with the desired free pigments. However, the new pigments must have suitable chemistry for favourable interactions with binding site residues, making precise control of which pigments can bind challenging [32].…”