Accelerating photoprotection recovery in soybean plants boosts crop yield

Bioengineering soybean plants to improve regulation of photoprotection – a natural process that enables plants to cope with damaging excess absorbed light energy in full sunlight – improved soybean seed yield by up to 33% in field trials, researchers report. The findings could enable a much-needed strategy to increase crop yield and support global food security sustainably. Improving photosynthesis in food crops has been suggested as a sustainable way to increase crop yields and mitigate looming global food shortages without having to bring more lands into agricultural production. Plants in full sunlight dissipate potentially damaging excess absorbed light energy as heat through a mechanism called nonphotochemical quenching (NPQ). However, while this process is crucial to protecting a plant’s photosynthetic apparatus from too much sun, NPQ mechanisms can be slow to relax after transitions to shade, and during the frequent sun-shade transitions that often occur within crop canopies, photosynthetic efficiency can be significantly reduced. For soybean, slow NPQ relaxation during these transitions is estimated to cost more than 11% of daily carbon assimilation. Bioengineered acceleration of NPQ relaxation has been shown to increase the photosynthetic efficiency and biomass in field-grown tobacco plants. Building off this previous research, and to determine if the approach could be applied to a major food crop, Amanda De Souza and colleagues engineered the same change into the widely cultivated soybean plant – the 4^th most important grain crop and the most important source of vegetable protein globally. In replicated field trials, De Souza et al. found that photosynthetic efficiency in the modified plants was higher during fluctuating light conditions and resulted in yield up to 33% higher than unmodified plants across 5 independent events. And, despite the increased plant yield, seed protein and oil content remained unaltered.