A team led by scientists at the University of California, Davis (UC Davis) found that a single gene plays a key role in determining the male and female flowering cycle of avocado trees.
The discovery could allow breeders to identify flowering types much earlier in a plant’s development, supporting the creation of new varieties and improving pollination strategies in commercial orchards.
Why do avocado flowers switch between male and female phases?
All avocado trees are hermaphrodites, but their flowers do not function as male and female at the same time. At certain times of the day, flowers release pollen, while at others they are receptive to pollination.
Around half of avocado trees, classified as Type A, open in the female phase in the morning and in the male phase in the afternoon. Type B trees follow the opposite schedule.
This alternating pattern helps limit self-pollination and encourages pollen exchange between trees. For this reason, growers commonly plant a combination of Type A and Type B varieties within the same orchard to support effective pollination.
The SDMYB gene at the heart of the discovery
To understand the genetic basis of this mechanism, researchers analysed the genomes of hundreds of avocado trees grown as part of collaborative research at the University of California, Riverside.
By comparing the trees’ genetic profiles with their flowering behaviour, the team identified a gene called SDMYB, which is closely associated with whether a tree follows a Type A or Type B flowering schedule.
According to the researchers, the genetic variation behind this mechanism evolved around 42 million years ago.
Avoiding a 10- to 15-year wait
The discovery could have major implications for avocado breeding. Until now, breeders had to wait for an avocado tree to flower before determining whether it belonged to Type A or Type B.
However, avocado trees can take 10 to 15 years to flower for the first time, creating a significant bottleneck for breeding and research programs.
Genetic markers associated with SDMYB could now make it possible to determine flowering type at the seedling stage, without waiting for trees to reach maturity.
A promising step forward for avocado breeding
For breeders, the ability to identify Type A and Type B plants at an early stage could accelerate crossing programs and support the development of new varieties. It could also help growers and researchers design orchards with varietal combinations better suited to pollination and yield objectives.
The discovery provides a genetic explanation for a pollination mechanism observed for more than a century and opens new opportunities for genetic innovation and varietal improvement in the global avocado industry.