Optimization of Light-Harvesting Pigment Improves Photosynthetic Efficiency

Abstract

Maximizing light capture by light-harvesting pigment optimization represents an attractive but challenging strategy to improve photosynthetic efficiency. Here, we report that loss of a previously uncharacterized gene, HIGH PHOTOSYNTHETIC EFFICIENCY1 (HPE1), optimizes light-harvesting pigments, leading to improved photosynthetic efficiency and biomass production. Arabidopsis (Arabidopsis thaliana) hpe1 mutants show faster electron transport and increased contents of carbohydrates. HPE1 encodes a chloroplast protein containing an RNA recognition motif that directly associates with and regulates the splicing of target RNAs of plastid genes. HPE1 also interacts with other plastid RNA-splicing factors, including CAF1 and OTP51, which share common targets with HPE1. Deficiency of HPE1 alters the expression of nucleus-encoded chlorophyll-related genes, probably through plastid-to-nucleus signaling, causing decreased total content of chlorophyll (a+b) in a limited range but increased chlorophyll a/b ratio. Interestingly, this adjustment of light-harvesting pigment reduces antenna size, improves light capture, decreases energy loss, mitigates photodamage, and enhances photosynthetic quantum yield during photosynthesis. Our findings suggest a novel strategy to optimize light-harvesting pigments that improves photosynthetic efficiency and biomass production in higher plants.

An Arabidopsis mutant with high operating efficiency of Photosystem II and low chlorophyll fluorescence

“…The CF characteristics of the hpe1 mutants and LCF1 are very similar, having low CF, as well as high φPSII and F q ′/F v ′ (also known as qP) 11 . However, marked differences exist.…”

Current and possible approaches for improving photosynthetic efficiency

“…Mutant tobacco plants possessing truncated light-harvesting chlorophyll antenna size (TLA) exhibited 25% higher stem and leaf biomass [39]. The loss of the regulator protein HPE1 also reduced photosynthetic antennae size and led to improved photosynthesis and biomass production of Arabidopsis thaliana mutants [40]. The optimisation of plant architecture may also prevent futile over-absorption of light by the upper leaves leading more light absorption for shade leaves.…”

Enhancing photosynthesis in plants: the light reactions

“…Pot and field experiments using rice with up to 50% less chlorophyll content showed an increase in the rates of photosynthesis of up to 40%, displayed elevated concentrations of ribulose-1,5-bisphosphate carboxylase/oxygenase and faster growth rates, which translated into similar yields to the wild-type in less time [ 20 ]. Another mutant of Arabidopsis thaliana , possibly affected in the regulation of chlorophyll synthesis, showed improvements in light use, which translated into a 50% increase in the amounts of accumulated glucose and fructose, as well as more than 10% dry-weight biomass in mature plants [ 21 ].…”