PaDSPD, a MYB-like transcription factor is linked with the Diurnally Synchronized Protogynous Dichogamy flowering type in avocado.

Authors: KHAN, ADIL - Oak Ridge Institute For Science And Education (ORISE); ELTAHER, SHAMSELDEEN - Oak Ridge Institute For Science And Education (ORISE); Freeman, Barbara; Ali, Gul

Submitted to: Fruit Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2025
Publication Date: 1/29/2026
Citation: Khan, A., Eltaher, S., Freeman, B.L., Ali, G.S. 2026. PaDSPD, a MYB-like transcription factor is linked with the Diurnally Synchronized Protogynous Dichogamy flowering type in avocado.. Fruit Research. https://doi.org/10.48130/frures-0025-0043.
DOI: https://doi.org/10.48130/frures-0025-0043

Interpretive Summary: Due to their recognized health benefits, avocados have witnessed increased popularity and consumption worldwide. Currently most of the avocados consumed in the U.S. are imported. Due to their high value ($500+ million farm gate value), there is a need for developing new superior varieties that have desirable traits that fit the needs of consumers, producers and packers along the supply chain. Avocado varieties are classified into two types: Flowers of Type A cultivars open as female in the morning on day 1 and as male in the afternoon on day 2, while those of Type B cultivars open as female in the afternoon on day 1 and as male in the morning on day 2. This flowering system promotes cross-pollination and is associated with higher yield in some cultivars. Using millions of molecular markers, ARS scientists identified the gene that controls flowering type in avocado. To accelerate breeding new avocado varieties through marker-assisted selection, they also developed molecular markers targeting this gene. These markers successfully distinguished Type A and Type B accessions with perfect accuracy. These findings contribute to the genetic dissection of avocado flowering type and offer molecular markers for breeding programs aimed at improving avocado pollination efficiency and productivity. Application of these markers in breeding are expected to significantly improve and accelerate breeding avocado varieties with a mixture of flowering types.

Technical Abstract: Avocado (Persea americana) exhibits a distinctive flowering pattern in which each flower opens first as a female and later as a male in a process known as diurnally synchronous protogynous dichogamy (DSPD). Avocado varieties are classified into two types: Flowers of Type A cultivars open as female in the morning on day 1 and as male in the afternoon on day 2, while those of Type B cultivars open as female in the afternoon on day 1 and as male in the morning on day 2. The DSPD flowering system hinders self-pollination and promotes cross-pollination to maintain genetic diversity and is linked with higher yield in some cultivars. However, the genetic and molecular mechanism controlling DSPD is not fully known, limiting breeding efforts to improve avocado pollination compatibility and yield. In this study, using high-density markers, we conducted population structure analyses of a geographically diverse avocado collection, which revealed three genetically diverse and distinct subgroups corresponding to the major geographical origins of avocado: Mexican, Guatemalan, and West Indian. This panel, which includes both Type A and B cultivars, was used for genome-wide association studies (GWAS) employing multiple models (EMAXX, GLM, and MLM). These analyses identified a precise 20-Kb genomic region on chromosome 10 associated with flowering type A and B. Remarkably, all significant markers were delineated to a single gene encoding an R2R3 type MYB-like transcription factor, named here as Persea americana diurnally synchronous protogynous dichogamy (PaDSPD). These results were verified using bulked segregant analyses in a mapping population segregating for flowering types. Analysis of marker genotyping data revealed that Type A always occurs as heterozygous and Type B as homozygous. Mendelian segregation analysis revealed that flowering type in avocado is inherited in a modified 2:1 (Type A: Type B) ratio suggesting that one of the homozygous genotypes is likely lethal. Amino acid comparisons of the two heterozygous PaDSPD alleles revealed several non-synonymous amino acid substitutions, which, along with possible differential transcriptional regulation, potentially influence the contrasting flowering types. For marker-assisted selection, competitive allele-specific PCR markers were developed targeting the PaDSPD variants. These markers successfully distinguished Type A and Type B accessions with perfect accuracy. These findings contribute to the genetic dissection of avocado flowering type and offer molecular markers for breeding programs aimed at improving avocado pollination efficiency and productivity.