title: Enhanced Thermostability of Arabidopsis Rubisco activase improves photosynthesis and growth rates under moderate heat stress.
abstract: Plant photosynthesis declines when the temperature exceeds its optimum range. Recent evidence indicates that the reduction in photosynthesis is linked to ribulose-1,5-bis-phosphate carboxylase/oxygenase (Rubisco) deactivation due to the inhibition of Rubisco activase (RCA) under moderately elevated temperatures. To test the hypothesis that thermostable RCA can improve photosynthesis under elevated temperatures, we used gene shuffling technology to generate several Arabidopsis thaliana RCA1 (short isoform) variants exhibiting improved thermostability. Wild-type RCA1 and selected thermostable RCA1 variants were introduced into an Arabidopsis RCA deletion (Deltarca) line. In a long-term growth test at either constant 26 degrees C or daily 4-h 30 degrees C exposure, the transgenic lines with the thermostable RCA1 variants exhibited higher photosynthetic rates, improved development patterns, higher biomass, and increased seed yields compared with the lines expressing wild-type RCA1 and a slight improvement compared with untransformed Arabidopsis plants. These results provide clear evidence that RCA is a major limiting factor in plant photosynthesis under moderately elevated temperatures and a potential target for genetic manipulation to improve crop plants productivity under heat stress conditions.
authors.affiliation: Pioneer Hi-Bred International, DuPont Agriculture and Nutrition, Redwood City, California 94063, USA.
authors.forename: Itzhak
authors.initials: I
authors.lastname: Kurek
authors.forename: Thom Kai
authors.initials: TK
authors.lastname: Chang
authors.forename: Sean M
authors.initials: SM
authors.lastname: Bertain
authors.forename: Alfredo
authors.initials: A
authors.lastname: Madrigal
authors.forename: Lu
authors.initials: L
authors.lastname: Liu
authors.forename: Michael W
authors.initials: MW
authors.lastname: Lassner
authors.forename: Genhai
authors.initials: G
authors.lastname: Zhu
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009154:Mutation; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D013696:Temperature
chemical_list: D010940:Plant Proteins; C054765:rca protein, plant