[MADS-box genes controlling inflorescence morphogenesis in sunflower].

Area of Science:

• Plant developmental genetics
• Molecular biology of flowering plants

Context:

• MADS-box genes are crucial regulators of plant ontogeny, particularly floral organ induction and development.
• Eight full-length Helianthus annuus MADS (HAM) gene cDNAs were isolated from sunflower, encoding MADS-box transcription factors expressed in inflorescence tissues.

Purpose:

• To classify HAM proteins within the ABCDE floral organ identity model based on structural homology.
• To investigate the role of specific HAM genes (HAM45, HAM59, HAM75, HAM92, HAM31, HAM2, HAM63, HAM91, HAM137) in determining floral and inflorescence meristem identity and organ development.
• To analyze MADS-box gene expression patterns to understand the developmental differences between sunflower flower types.

Summary:

• HAM proteins were classified according to the ABCDE model: HAM45/HAM59 (C function), HAM75/HAM92 (A identity), HAM31/HAM2/HAM63/HAM91 (B function), and HAM137 (E function).
• Analysis revealed that differential expression of MADS-box genes, specifically the absence of HAM59 in ray flower initiation, likely accounts for the structural and functional divergence between ray and tubular flowers in sunflower inflorescences.

Impact:

• Provides insights into the genetic mechanisms underlying floral diversification in sunflower.
• Contributes to the understanding of MADS-box gene function in plant development, applicable to other species.
• Establishes a foundation for future research into sunflower breeding and floral trait manipulation.