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Horticulture Research 

  2022-01-18

doi: 10.1093/hr/uhab044

Most commercial peach [Prunus persica (L.) Batsch] cultivars have leaves with extrafloral nectaries. Breeders have selected this trait over time because they have observed that peach trees without nectary are more susceptible to powdery mildew, a major peach disease. The nectaries are controlled by a locus (E) mapped to chromosome 7, but the underlying genetic factor has remained unknown until now.

In order to shed light on this point, we developed a mapping population of 833 individuals resulting from the selfing of ‘Malo Konare’, a Bulgarian peach cultivar, heterozygous for the trait.

High-resolution mapping delimited a 40.6 kbp region comprising four genes. Three double recombinants identified Prupe.7G121100, an LMI1-like transcription factor, as a candidate. By comparing genomic resequencing data from individuals with contrasting phenotypes, a MITE-like, transposable element of the hAT superfamily (mMoshan), was identified in the third exon of Prupe.7G121100. Insertion of the transposon is positively correlated with increased expression of Prupe.7G121100. Finally, a PCR marker, designed from sequence variants, made it possible to discriminate between the 271 individuals of various origins used for validation.

These findings provide valuable information on the genetic control of a poorly known trait so far, although long selected in peach.