California, USA – Scientists have revealed how avocado flowers switch between male and female roles throughout the day, solving a long-standing mystery of avocado pollination.

A new study led by researchers from the University of California, Davis, found that this daily rhythm is controlled by variation in a single gene that evolved about 42 million years ago.

Avocado trees are hermaphrodites, but their flowers function either as male by releasing pollen or as female by receiving pollen. Some trees open female flowers in the morning and male flowers in the afternoon, while others follow the opposite schedule.

Researchers discovered that a gene called SDMYB is linked to whether avocado trees follow the A-type or B-type flowering pattern. This timing helps reduce self-pollination and allows avocado trees to exchange pollen throughout the day.

“Our study provides a genetic explanation for a century-old mystery of avocado pollination,” said Jeffrey Groh, the study’s first author.

The team found that the same two versions of SDMYB are shared by at least 26 related tree species, suggesting the mechanism may regulate flowering behavior beyond avocados.

“We were blown away by the idea that these plants have been alternating male and female activity over the course of a day for over 40 million years, over potentially hundreds of species,” said Graham Coop, a senior author of the study.

Podcast: Play in new window | Download