All avocado trees are hermaphrodites, but at any given time their flowers function either as male by releasing pollen, or as female by receiving pollen. Approximately half of all avocado trees (“A-type” plants) open female flowers in the morning and male flowers in the afternoon, whereas the other half (“B-type” plants) follow the opposite pattern. This partitioning minimizes the risk of self-pollination, which can result in inbreeding. Avocado breeders have known about this for over a hundred years, and because these two types easily pollinate one another, avocado farmers usually try to plant a mixture of A- and B-type trees.
To avoid self-pollination, avocado trees alternate between opening male and female flowers at different times of day. Some avocados are female in the morning and male in the afternoon, while others are on the opposite schedule. How avocados do this has been unclear — until now.
In a new study, a team led by researchers from the University of California, Davis, revealed that this rhythm is dictated by variation in a single gene that evolved about 42 million years ago. Published in Proceedings of the National Academy of Sciences, this finding could help avocado breeders and researchers quickly sort seedlings to maximize yield and develop new varieties.
Read the news piece from UC Riverside:
https://news.ucr.edu/articles/2026/07/28/gene-discovery-could-shave-years-avocado-breeding