Genotype‐dependent changes of cell wall composition influence physiological traits of a long and a non‐long shelf‐life tomato genotypes under distinct water regimes

Water shortage strongly affects plants' physiological performance. Since tomato (Solanum lycopersicum) non‐long shelf‐life (nLSL) and long shelf‐life (LSL) genotypes differently face water deprivation, we subjected a nLSL and a LSL genotype to four treatments: control (well watering), short‐term water deficit stress at 40% field capacity (FC) (ST 40% FC), short‐term water deficit stress at 30% FC (ST 30% FC), and short‐term water deficit stress at 30% FC followed by recovery (ST 30% FC‐Rec). Treatments promoted genotype‐dependent elastic adjustments accompanied by distinct photosynthetic responses. While the nLSL genotype largely modified mesophyll conductance (g (m)) across treatments, it was kept within a narrow range in the LSL genotype. However, similar g (m) values were achieved under ST 30% FC conditions. Particularly, modifications in the relative abundance of cell wall components and in sub‐cellular anatomic parameters such as the chloroplast surface area exposed to intercellular air space per leaf area (S (c)/S) and the cell wall thickness (T (cw)) regulated g (m) in the LSL genotype. Instead, only changes in foliar structure at the supra‐cellular level influenced g (m) in the nLSL genotype. Even though further experiments testing a larger range of genotypes and treatments would be valuable to support our conclusions, we show that even genotypes of the same species can present different elastic, anatomical, and cell wall composition‐mediated mechanisms to regulate g (m) when subjected to distinct water regimes.