Genotype-dependent response to carbon availability in growing tomato fruit

Area of Science:

• Plant Biology
• Genetics
• Molecular Biology

Background:

• Tomato fruit development is a complex process influenced by genetic makeup and environmental factors.
• Carbon availability significantly impacts fruit growth and biochemical composition.
• Understanding genotype-environment interactions is crucial for crop improvement.

Purpose of the Study:

• To investigate how fruit phenotypic responses to altered carbon availability are modulated by genotype.
• To identify genotype-dependent and -independent gene expression changes related to tomato fruit growth and composition variations.
• To explore the molecular mechanisms underlying these responses.

Main Methods:

• Cultivation of a parental line (Solanum lycopersicum) and an introgression line under varying fruit loads (FL).
• Phenotypic analysis of fruit growth parameters, including cell number, cell size, and developmental period.
• Gene expression profiling using microarrays and RT-qPCR to monitor transcriptional and post-transcriptional regulation.

Main Results:

• Lowering fruit load increased fruit cell number and reduced developmental period in both genotypes.
• Fruit cell size increased only in the parental line under altered fruit load.
• Gene expression analysis revealed genotype-by-fruit load interactions in 99 genes, primarily related to hormonal and stress responses, and gene expression kinetics. Specific links were found between aquaporin and invertase expression and fruit water and sugar content, respectively.

Conclusions:

• Tomato fruit responses to carbon availability are age- and genotype-dependent at both phenotypic and gene expression levels.
• Gene expression modifications involved regulatory systems more than primary metabolism adjustments.
• Identified specific gene expression patterns linked to fruit water and sugar content, providing insights into fruit quality regulation.