An ancient genetic switch controls avocado flowering time.

An ancient trans-specific genetic system linked to floral timing controls heterodichogamy in avocado, maintained for over 42 million years.

• Why it matters: Understanding this system is important because it reveals how reproductive polymorphisms are preserved over evolutionary timescales, impacting avocado breeding and diversity.
• What they did: The study identified SDMYB, a gene strongly associated with the reciprocal A and B flowering types, indicating its role in coordinating female and male floral phases.
• The result: This finding suggests that the ancient SDMYB system underpins floral timing and reproductive polymorphism in avocado, offering insights into plant evolutionary mechanisms.