PaDSPD, a MYB-like transcription factor is linked with the diurnally synchronized protogynous dichogamy flowering type in avocado

Avocado (Persea americana) exhibits a distinctive flowering pattern known as diurnally synchronous protogynous dichogamy (DSPD), in which flowers of Type A cultivars open as female in the morning on day one and as male in the afternoon on day two, while those of Type B cultivars open as female in the afternoon on day one and as male in the morning on day two. The DSPD flowering system promotes cross-pollination and higher yield in some cultivars. However, the genetic and molecular mechanism controlling DSPD is not fully known. Genome-wide association studies of this panel resulted in identifying 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 population segregating for flowering types. Analysis of marker data revealed that Type A always occurs as a heterozygous and Type B as a 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. For marker-assisted selection, competitive allele-specific PCR markers were developed, which 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.