Advances in Citrus Flowering: A Review

Area of Science:

• Plant Science
• Horticulture
• Molecular Biology

Background:

• Citrus species are polycarpic and evergreen, flowering based on genotype and climate.
• Floral induction requires low temperatures and water deficit, preceding bud sprouting and differentiation.
• Fruit presence inhibits nearby bud sprouting, leading to alternate bearing in some citrus cultivars.

Purpose of the Study:

• To provide a comprehensive overview of the citrus flowering process.
• To synthesize research on citrus flowering over the past half-century.
• To highlight advances in molecular biology and gene regulation in citrus flowering.

Main Methods:

• Review of historical and recent research on citrus flowering.
• Analysis of factors influencing floral induction and differentiation (temperature, water stress, fruit load).
• Examination of key flowering genes (e.g., CiFT3, CcMADS19, CsLFY, CsTFL1) and their roles.
• Discussion of horticultural techniques, including gibberellin treatments.

Main Results:

• Flowering is regulated by environmental cues and internal factors like fruit dominance and plant age.
• Key genes in leaves and buds control flowering time and meristem identity.
• Gibberellin treatments can modify gene expression to control bud sprouting and flowering.
• Research has evolved from plant growth regulators to molecular mechanisms and gene transformation.

Conclusions:

• Understanding citrus flowering mechanisms is crucial for horticultural management.
• Molecular biology tools have significantly advanced the study of citrus reproductive processes.
• Future research directions include further exploration of gene transcription and plant transformation for improved citrus cultivation.