Modifying Plant Photosynthesis and Growth via Simultaneous Chloroplast Transformation of Rubisco Large and Small Subunits. Issue 9 (9th July 2020)

• Record Type: Journal Article
• Authors: Martin-Avila, Elena; Lim, Yi-Leen; Birch, Rosemary; Dirk, Lynnette M.A.; Buck, Sally; Rhodes, Timothy; Sharwood, Robert E.; Kapralov, Maxim V.; Whitney, Spencer M.
• Is Part Of: The Plant Cell. Volume 32:Issue 9(2020)
• Page Start: 2898
• Page End: 2916
• Publication Date: 2020-07-09
• DOI: 10.1105/tpc.20.00288
• Languages: English
• ISSNs: 1040-4651

Abstract

Abstract : Erasing Rubisco small subunit nuclear synthesis in tobacco provides a new plant chassis for investigating novel Rubisco complexes in a whole plant context via chloroplast transformation of both its large and small subunits. Abstract: Engineering improved Rubisco for the enhancement of photosynthesis is challenged by the alternate locations of the chloroplast rbcL gene and nuclear RbcS genes. Here we develop an RNAi- RbcS tobacco ( Nicotiana tabacum ) master-line, tobRrΔS, for producing homogenous plant Rubisco by rbc L- rbc S operon chloroplast transformation. Four genotypes encoding alternative rbcS genes and adjoining 5′-intergenic sequences revealed that Rubisco production was highest (50% of the wild type) in the lines incorporating a rbcS gene whose codon use and 5′ untranslated-region matched rbcL . Additional tobacco genotypes produced here incorporated differing potato ( Solanum tuberosum ) rbcL - rbcS operons that either encoded one of three mesophyll small subunits (pS1, pS2, and pS3) or the potato trichome pS T -subunit. The pS3-subunit caused impairment of potato Rubisco production by ∼15% relative to the lines producing pS1, pS2, or pS T . However, the βA-βB loop Asn-55-His and Lys-57-Ser substitutions in the pS3-subunit improved carboxylation rates by 13% and carboxylation efficiency (CE) by 17%, relative to potato Rubisco incorporating pS1 or pS2-subunits. Tobacco photosynthesis and growth were most impaired in lines producing potato Rubisco incorporating the pS T -subunit, which reduced CE and CO2 /O2 specificity 40% and 15%, respectively. Returning the rbcS gene to the plant plastome provides an effective bioengineering chassis for introduction and evaluation of novel homogeneous Rubisco complexes in a whole plant context.