Plant Biotechnol J. 2023 Feb 14. doi: 10.1111/pbi.14030. Online ahead of print.

ABSTRACT

Sorghum is one of the most important crops providing food and feed in many of the world’s harsher environments. Sorghum utilises the C4 pathway of photosynthesis in which a biochemical carbon concentrating mechanism results in high CO2 assimilation rates. Overexpressing the Rieske subunit of the Cytochrome b6 f complex was previously shown to increase the rate of photosynthetic electron transport and stimulate CO2 assimilation in the model C4 plant Setaria viridis. To test whether productivity of C4 crops could be improved by Rieske overexpression, we created transgenic Sorghum bicolor Tx430 plants with increased Rieske content. The transgenic plants showed no marked changes in abundance of other photosynthetic proteins or chlorophyll content. The steady-state rates of electron transport and CO2 assimilation did not differ between the plants with increased Rieske abundance and control plants, suggesting that Cytochrome b6 f is not the only factor limiting electron transport in sorghum at high light and high CO2 . However, faster responses of non-photochemical quenching as well as an elevated yield of Photosystem II and an increased CO2 assimilation rate were observed from the plants overexpressing Rieske during the induction, a process of activation of photosynthesis upon the dark-light transition. Sorghum with increased Rieske content could produce more biomass and grain when grow in glasshouse conditions. Our results indicate that increasing Rieske content has potential to boost productivity of sorghum and other C4 crops by improving the efficiency of light utilisation and conversion to biomass through the faster induction of photosynthesis.

PMID:36789455 | DOI:10.1111/pbi.14030