ORANGE negatively regulates flowering time in Arabidopsisthaliana

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• Floral transition is crucial for plant reproduction, regulated by photoperiod, vernalization, autonomous, and gibberellin (GA) pathways.
• The ORANGE (OR) protein, identified in cauliflower mutants, influences carotenoid biosynthesis and flowering time.

Purpose of the Study:

• To investigate the role of the ORANGE (OR) protein in regulating floral transition in Arabidopsis thaliana.
• To elucidate the molecular mechanism by which OR affects flowering time.

Main Methods:

• Overexpression of OR in Arabidopsis thaliana.
• Analysis of flowering time phenotypes.
• Quantitative analysis of flowering integrator gene expression (FT, SOC1, CO).
• Diurnal and long-day cycle expression profiling.

Main Results:

• Overexpression of OR resulted in a delayed-flowering phenotype, similar to cauliflower mutants.
• OR negatively regulates the expression of FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1).
• GA3 and vernalization treatments did not rescue the delayed-flowering phenotype.
• OR transcript levels fluctuated inversely to FT transcript levels diurnally.
• OR overexpression repressed the accumulation of CONSTANS (CO), FT, and SOC1 transcripts under long-day conditions.

Conclusions:

• OR acts as a negative regulator of floral transition in Arabidopsis.
• The delayed-flowering phenotype induced by OR is mediated through the CONSTANS (CO)-FLOWERING LOCUS T (FT)-SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) photoperiodic pathway.
• OR's function in repressing flowering is independent of GA-dependent and SOC1-mediated vernalization pathways.