Gene regulation in parthenocarpic tomato fruit

Area of Science:

• Plant Biotechnology
• Molecular Biology
• Agricultural Science

Background:

• Parthenocarpy, the development of fruit without fertilization, is a desirable trait for commercial fruit production.
• Achieving parthenocarpy without compromising fruit quality (structure, flavor, nutrition) remains a challenge.
• Genetic engineering offers a potential route to induce parthenocarpy in crops like tomatoes.

Purpose of the Study:

• To develop parthenocarpic transgenic tomato plants using genes for auxin synthesis or response.
• To investigate the transcriptomic and metabolomic changes associated with induced parthenocarpy.
• To evaluate the commercial viability of parthenocarpy achieved through specific gene regulation.

Main Methods:

• Transgenic tomato plants (cv MicroTom) were created by regulating auxin synthesis (iaaM) or response (rolB) genes.
• Gene expression was driven by DefH9 or Arabidopsis thaliana's INNER NO OUTER (INO) promoter.
• Transcriptomic and metabolomic analyses were performed using microarrays, RT-PCR, and mass spectrometry.

Main Results:

• Seedless parthenocarpic fruits were successfully produced by expressing auxin synthesis or response genes.
• While fruit shape varied, no correlation was found between seed number, transgene, and fruit size.
• 17% of measured genes showed significant expression differences, particularly those related to cell wall, hormone metabolism (auxin), and sugar/lipid metabolism.

Conclusions:

• Ovule-specific alteration of auxin synthesis or response using the INO promoter effectively induces parthenocarpy in tomatoes.
• Induced parthenocarpy did not fundamentally alter the metabolic profile, despite minor changes in specific metabolites and gene expression.
• This approach holds commercial potential for developing seedless fruits where parthenocarpy is desirable.