Phenotypic, genetic and molecular characterization of the parthenocarpic fruit (pat) mutant and identification of the candidate gene in tomato (Solanum lycopersicum L.)
Author(s)
Picarella, Maurizio Enea
Date Issued
December 11, 2017
Type
Doctoral Thesis
Abstract
Parthenocarpy is a developmental modification that entails fruit setting independently of
pollination and fertilization. In parthenocarpic genotypes, fruit set can be achieved under
pollen-limiting environmental conditions and in sterile genotypes. Parthenocarpy is a trait
linked to fruit quality because it is a pre-requisite for seedlessness and is often associated with
further positive quality aspects. Among the different sources of genetic parthenocarpy
described in tomato, the parthenocarpic fruit pat mutation is of particular interest because
of its strong expressivity, high fruit set and enhanced fruit quality. The complexity of the pat
syndrome associates a strong competence for parthenocarpy with a complex floral
phenotype involving stamen and ovule developmental aberrations. Previously, the Pat locus
was mapped in a .9 cM window of chromosome 3, comprising nine loci. By comparative
sequence analysis between the WT and the pat lines, a candidate gene was identified. A
complementation experiment for the pat mutant line was carried out, by using a gene cassette
consisting of the coding sequence of the candidate gene, a class-III HD-Zip gene SlHB15,
driven by a constitutive promoter CaMV35S. Despite no WT phenotype could be scored in
the T generation, following post-transcriptional trans inactivation events, a number of T
plants of the WT line, co-suppressed for SlHB5, were isolated showing some of the traits of
the pat syndrome, among which anther homeotic aberrations, ovule abortion and reduction of
seed number in the fruit. Further phenotypic and molecular characterization of the pat
mutant fostered the potential role of the SlHB15pat allele in the pat syndrome.
Additional information
Dottorato di ricerca in Scienze delle produzioni vegetali e animali
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