Abstract
Enhanced photosynthesis is strictly associated with to productivity and it can be accomplished by genetic approaches through identification of genetic variation. By using a Solanum pennellii introgression lines (ILs) population, it was previously verified that, under normal (CO2), IL 2–5 and 2–6 display increased photosynthetic rates by up to 20% in comparison with their parental background (M82). However, the physiological mechanisms involved in the enhanced CO2 assimilation exhibited by these lines remained unknown, precluding their use for further biotechnological applications. Thereby, here we attempted to uncover the physiological factors involved in the upregulation of photosynthesis in ILs 2–5 and 2–6 under normal (CO2) as well as under elevated (CO2). The results provide evidence for increased biochemical capacity (higher maximum carboxylation velocity and maximum electron transport rate) in plants from IL 2–5 and 2–6, whereas the diffusive components (stomatal and mesophyll conductances) were unaltered in these ILs in comparison to M82. Our analyses revealed that the higher photosynthetic rate observed in these ILs was associated with higher levels of starch as well as total protein levels, specially increased RuBisCO content. Further analyses performed in plants under high (CO2) confirmed that biochemical properties are involved in genetic variation on chromosome 2 related to enhanced photosynthesis.
Highlights
Photosynthesis (A) is the main driving force for plant growth and biomass production having a central position for breeders seeking to increase crop yield (Evans, 2013; Nunes-Nesi et al, 2016; Nuccio et al, 2017; Batista-Silva et al, 2020; Flexas and Carriquí, 2020)
Given our previous demonstration that CO2 assimilation rates of both introgression lines (ILs) 2–5 and 2–6 plants were on average 20% higher compared to M82, we decided to deeper investigate the physiological mechanisms responsible for their enhanced CO2 assimilation
We observed that both ILs exhibited substantially higher A (∼22%), and ETR under high (CO2; Table 2), whereas no alterations were observed under ambient (CO2) in the lines compared to their respective M82
Summary
Photosynthesis (A) is the main driving force for plant growth and biomass production having a central position for breeders seeking to increase crop yield (Evans, 2013; Nunes-Nesi et al, 2016; Nuccio et al, 2017; Batista-Silva et al, 2020; Flexas and Carriquí, 2020). High Photosynthesis in a Solanum pennellii QTL exhibiting higher photosynthetic rates. Understanding the mechanisms involved in the photosynthesis associated traits are required for improving the photosynthetic efficiency in crop species. A can be improved by changes in stomatal properties (Rebetzke et al, 2013), ribulose 1,5 bisphosphate carboxilase oxigenase (RuBisCO) kinetic attributes (Parry et al, 2013), and by modifying expression of others enzymes involved in carbon reduction reactions (Miyagawa et al, 2001; Lefebvre et al, 2005; Driever et al, 2017). Alterations in A may be associated with diffusional limitations as those derived from changes in stomatal (gs) and mesophyll (gm) conductances which are dependent on leaf anatomical and physiological properties and influenced by environmental cues (Flexas et al, 2007, 2012; Vrabl et al, 2009; Galmés et al, 2011). Enrichment in the availability of atmospheric (CO2) augments RuBisCO carboxylase activity leading to reduced photorespiratory process, improving carbon gains (Long et al, 2004; Peterhansel et al, 2010)
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