A Chimeric TGA Repressor Slows Down Fruit Maturation and Ripening in Tomato

Area of Science:

• Plant Biology
• Molecular Biology
• Fruit Development

Background:

• The bZIP transcription factor (TF) SlTGA2.2 is implicated in tomato fruit growth and ripening.
• TGA TFs are known regulators of salicylic acid-dependent systemic acquired resistance.

Purpose of the Study:

• Investigate the role of SlTGA2.2 in tomato fruit growth and maturation.
• Utilize a fruit-specific promoter to control SlTGA2.2 activity during development.

Main Methods:

• Generated a SlTGA2.2-SRDX chimeric repressor under the control of the fruit-specific SlPPC2 promoter (PPC2pro).
• Analyzed fruit development, metabolism, chloroplast structure, and ripening progression.
• Employed RNA sequencing and plant hormone analyses to decipher molecular mechanisms.

Main Results:

• SlTGA2.2-SRDX repressor expression altered early fruit development and metabolism, affecting chloroplasts.
• Fruit maturation was extended, and ripening was significantly slowed.
• PPC2pro:SlTGA2.2-SRDX fruits remained immature due to modified hormonal signaling and suppressed ripening regulators (MADS-RIN, NAC-NOR).

Conclusions:

• SlTGA2.2 plays a crucial role in the transition from tomato fruit growth to ripening.
• The study highlights the continuous developmental process from growth to maturation and ripening.
• The PPC2pro:SlTGA2.2-SRDX system provides a tool for studying the molecular basis of tomato fruit ripening.