---
title: "A Gene Found at UC Davis and UC Riverside Could Cut Years Off Avocado Breeding"
description: "Avocado trees come in two flowering types that have to pollinate each other, and until now the only way to know which type a seedling was involved waiting five to ten years for it to bloom. A gene identified this week lets breeders read it off the DNA instead."
category: "California"
category_url: https://herald.la/category/california
author: "Omar Haddad"
published: 2026-07-31T16:55:30.000Z
updated: 2026-07-31T16:55:30.000Z
canonical: https://herald.la/article/a-gene-found-at-uc-davis-and-uc-riverside-could-cut-years-off-avocado-breeding
tags: ["agriculture", "genetics", "avocado", "uc-riverside", "california-farming"]
---
# A Gene Found at UC Davis and UC Riverside Could Cut Years Off Avocado Breeding

Avocado trees come in two flowering types that have to pollinate each other, and until now the only way to know which type a seedling was involved waiting five to ten years for it to bloom. A gene identified this week lets breeders read it off the DNA instead.

The avocado has an unusual sex life, and it has been slowing down California's
breeding programs for a century.

Every avocado tree is one of two flowering types, A or B. Their schedules are
mirror images: when one type is releasing pollen, the other's flowers are
receptive. Plant only one type and the orchard pollinates itself poorly. Plant both
and it works. Growers have known this for generations without knowing why.

A study published Tuesday in the Proceedings of the National Academy of Sciences
identifies the gene behind it. Led by UC Davis with UC Riverside, whose Department
of Botany and Plant Sciences runs California's main avocado breeding program, the
researchers pinned the trait to a floral transcription factor they call SDMYB,
[according to UC Riverside](https://news.ucr.edu/articles/2026/07/28/gene-discovery-could-shave-years-avocado-breeding).

"Our study provides a genetic explanation for a century-old mystery of avocado
pollination," said Jeffrey Groh, the paper's first author, now at UC Berkeley.

## Why this is a breeding problem and not just a curiosity

Breeding a tree crop is slow in a way that breeding an annual is not. You plant a
seedling and then you wait, because the traits you are selecting for do not appear
until the tree is mature. For flowering type, that wait has been five to ten years.

Multiply that by the number of seedlings a program has to grow to find one worth
keeping, and the arithmetic is brutal: most of the orchard is occupying land and
water for a decade to answer a question about a single trait.

The gene changes the order of operations. "Instead of waiting years for a tree to
flower, we can identify its flower type almost immediately using its DNA," said
Eric Focht, a UC Riverside researcher. His colleague Marllon Soares dos Santos put
the point about timing: "This is something we can begin using right away. We can
make those decisions at the beginning. That makes breeding much more efficient."

## The specific bottleneck it opens

The commercial problem is on the B side. Orchards need B-type trees for
pollination, but the B-types available have generally been the weaker fruit, so
growers plant them as a necessary compromise rather than for the crop. UC
Riverside's Luna UCR is the counterexample the program points to, a B-type bred to
carry commercial-quality fruit as well as pollen.

Being able to sort seedlings by type on day one means a program can screen a large
population for B-types and then spend the decade on the ones worth spending it on,
rather than discovering at year eight that a promising tree is the wrong type.

## What this does not do yet

It is a genetic marker, not a variety. Nothing about this shortens the time a new
avocado still needs in field trials, and nothing about it puts fruit in a Ventura
County orchard sooner than the ordinary cycle allows. The gain is at the front of
the pipeline, in what gets planted, not at the end.

That is still worth something in a state where avocado growers are contending with
water costs and import competition, and where the value of a breeding program lies
in how many candidates it can afford to evaluate. The answer to that question just
went up.

## Sources

- [Gene discovery could shave years off avocado breeding](https://news.ucr.edu/articles/2026/07/28/gene-discovery-could-shave-years-avocado-breeding)