Abstract
Changes in the atmospheric CO(2) concentration influence plant growth and development by affecting the morphological structure and photosynthetic performance. Despite evidence for the macro-effects of elevated CO(2) concentrations on plant morphology and yield in tomato, the gene regulatory network and key genes related to cross-regulation have not been reported. To identify the hub genes and metabolic pathways involved in the response of tomato to CO(2) enrichment, weighted gene co-expression network analysis was conducted using gene expression profiles obtained by RNA sequencing. The role of the photosynthesis-related gene Soly720 (Solyc01g007720) in CO(2)-enriched tomato plants was explored. Tomato plants responded to CO(2) enrichment primarily through RNA-related pathways and the metabolism of amino acids, fatty acids, and carbohydrates. The hub genes in co-expression networks were associated with plant growth and development, including cellular components and photosynthesis. Compared to wild-type plants, transgenic plants overexpressing the Soly720 gene exhibited 13.4%, 5.5%, 8.9%, and 4.1% increases in plant height, stem diameter, leaf length, and leaf width, respectively, under high-CO(2) conditions. The morphological improvements in transgenic plants were accompanied by enhancement of photosynthetic performance in terms of chlorophyll contents, photosynthetic characteristics, and key enzyme activities. This study elucidates the response network of tomato to CO(2) enrichment and demonstrates the regulatory role of Soly720 in photosynthesis under high-CO(2) conditions.