A procedure to introduce point mutations into the Rubisco large subunit gene in wild‐type plants. (11th March 2021)

• Record Type: Journal Article
• Authors: Lin, Myat T.; Orr, Douglas J.; Worrall, Dawn; Parry, Martin A. J.; Carmo‐Silva, Elizabete; Hanson, Maureen R.
• Is Part Of: Plant journal. Volume 106:Number 3(2021)
• Page Start: 876
• Page End: 887
• Publication Date: 2021-03-11
• Subjects: chloroplast transformation -- food security -- homologous recombination -- Rubisco -- photosynthesis -- site‐directed mutagenesis -- Nicotiana tabacum -- technical advance; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.15196
• Languages: English
• ISSNs: 0960-7412

Abstract

SUMMARY: Photosynthetic inefficiencies limit the productivity and sustainability of crop production and the resilience of agriculture to future societal and environmental challenges. Rubisco is a key target for improvement as it plays a central role in carbon fixation during photosynthesis and is remarkably inefficient. Introduction of mutations to the chloroplast‐encoded Rubisco large subunit rbc L is of particular interest for improving the catalytic activity and efficiency of the enzyme. However, manipulation of rbc L is hampered by its location in the plastome, with many species recalcitrant to plastome transformation, and by the plastid's efficient repair system, which can prevent effective maintenance of mutations introduced with homologous recombination. Here we present a system where the introduction of a number of silent mutations into rbc L within the model plant Nicotiana tabacum facilitates simplified screening via additional restriction enzyme sites. This system was used to successfully generate a range of transplastomic lines from wild‐type N. tabacum with stable point mutations within rbc L in 40% of the transformants, allowing assessment of the effect of these mutations on Rubisco assembly and activity. With further optimization the approach offers a viable way forward for mutagenic testing of Rubisco function in planta within tobacco and modification of rbc L in other crops where chloroplast transformation is feasible. The transformation strategy could also be applied to introduce point mutations in other chloroplast‐encoded genes. Significance Statement: A simplified transformation strategy was developed to perform site‐directed mutagenesis in the chloroplast‐encoded Rubisco large subunit of tobacco. This approach reduces unwanted mismatch repair events, enables rapid screening of transformed lines that possess desired mutations and can be applied to modify any chloroplast‐encoded gene in plant species amenable to plastid genome transformation.