get3b mutation affects CO2 assimilation
The proteomic analysis also suggested that components of the dark reaction were affected by the get3b mutation. Interestingly, not only three of four paralogous genes of the nuclear encoded small subunits but also the plastom encoded large subunit of RuBisCo were affected by the reduction or absence of GET3B. Additionally, RuBisCo assembly factors like RbcX, CPN60A1, CPN60B1 and CPN10-2 were significantly affected in get3b (Supplemental table S1). In total, these constitute six out of nine components necessary to synthesize RuBisCo in vitro (Aigner et al., 2017). In order to address this matter, we analyzed the CO2 assimilation ofA. thaliana seedlings by Infra-red gas analyzer (IRGA; Toro et al., 2019). The measurements revealed that get3b assimilated significantly less CO2 (Figure 3). During the measurements we included a complementation line that was previously used (Xing et al., 2017). The complementation line was able to rescue theget3b assimilation phenotype and restore the levels above those of the wild-type (Figure 3).
This and the previous data support the results of the proteomic analysis, that GET3B is required for an efficient light as well as dark reaction of photosynthesis.