Furbank, Robert T.Chitty, Julie A.Von Caemmerer, SusanneJenkins, Colin L.D.2025-05-232025-05-230032-0889http://www.scopus.com/inward/record.url?scp=0001393390&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733752942The C4 dicot Flaveria bidentis was genetically transformed with an antisense RNA construct targeted to the nuclear-encoded gene for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; RbcS). RbcS mRNA levels in leaves of transformants were reduced by as much as 80% compared to wild-type levels, and extractable enzyme activity was reduced by up to 85%. There was no significant effect of transformation with the gene construct on levels of other photosynthetic enzymes. Antisense transformants with reduced Rubisco activity exhibited a stunted phenotype. Rates of photosynthesis were reduced in air at high light and over a range of CO2 concentrations but were unaffected at low light. From these results we conclude that, as is the case in C3 plants, Rubisco activity is a major determinant of photosynthetic flux in C4 plants under high light intensities and air levels of CO2.10en199610.1104/pp.111.3.7250001393390