Vascular network in the pericarp of tomato fruit and implications for fruit size, quality, and drought response

The importance of the vascular network for transporting water, carbohydrate, and nutrient for sustaining plant growth and development in the vegetative body of plants is well known. Nevertheless, the vascular network within a fruit is still inadequately understood. Here we characterized the vascular network in the fruit pericarp of ten tomato genotypes varying in fruit size from 20 to 287 g (fresh mass) and investigated its relation with typical hydraulic and anatomical traits under well-watered and water deficit conditions. We found that larger fruits had lower vein length density, accompanied by more xylem vessels within a vascular bundle and lower water uptake capacity per fresh mass. Vein length density was positively correlated with total soluble solids while negatively correlated with mesocarp cell size. This study highlights the association between hydraulic function of the fruit peripheral vascular network and fruit size, likely opening up a new research avenue for understanding fruit evolution, aiding in selection for drought-tolerant genotypes, and encouraging integration of fruit venation patterns into research.