Overexpression of Rubisco subunits with RAF1 increases Rubisco content in maize. (October 2018)

• Record Type: Journal Article
• Authors: Salesse-Smith, Coralie; Sharwood, Robert; Busch, Florian; Kromdijk, Johannes; Bardal, Viktoriya; Stern, David
• Is Part Of: Nature plants. Volume 4:Number 10(2018)
• Page Start: 802
• Page End: 810
• Publication Date: 2018-10
• Subjects: Plants -- Periodicals; 580.5; 580 21
• DOI: 10.1038/s41477-018-0252-4
• Languages: English
• ISSNs: 2055-0278

Abstract

Abstract Rubisco catalyses a rate-limiting step in photosynthesis and has long been a target for improvement due to its slow turnover rate. An alternative to modifying catalytic properties of Rubisco is to increase its abundance within C4 plant chloroplasts, which might increase activity and confer a higher carbon assimilation rate. Here, we overexpress the Rubisco large (LS) and small (SS) subunits with the Rubisco assembly chaperone RUBISCO ASSEMBLY FACTOR 1 (RAF1). While overexpression of LS and/or SS had no discernable impact on Rubisco content, addition of RAF1 overexpression resulted in a >30% increase in Rubisco content. Gas exchange showed a 15% increase in CO2 assimilation (ASAT ) in UBI-LSSS-RAF1 transgenic plants, which correlated with increased fresh weight and in vitro Vcmax calculations. The divergence of Rubisco content and assimilation could be accounted for by the Rubisco activation state, which decreased up to 23%, suggesting that Rubisco activase may be limiting Vcmax, and impinging on the realization of photosynthetic potential from increased Rubisco content. Rubisco, which catalyses a major rate-limiting reaction in photosynthesis, is an important target for 'improvement'. This study shows that rather than specifically engineering Rubisco's properties, overexpression alone can increase the photosynthetic performance of transgenic maize plants.