Phenotypic and molecular characterization of ethylene biosynthesis in apples

Granozio, Serena Maria (2013) Phenotypic and molecular characterization of ethylene biosynthesis in apples, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Colture arboree ed agrosistemi forestali ornamentali e paesaggistici, 24 Ciclo. DOI 10.6092/unibo/amsdottorato/5526.
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Ethylene plays an important role in apple fruit development. Its biosynthesis is catalyzed by two enzymes ACS and ACO. The first is considered to catalyzes the rate-limiting step of ethylene production and in apple two different alleles (MdACS1-1 and MdACS1-2) of this gene have been identified. The presence in the promoter region of MdACS1-2 allele of a SINE insertion is considered to be responsible for a low transcription level and a pronounced reduction in ethylene production in apple cultivar homozygous for this allele. However, the specific expression of each MdACS1 allele has never been reported as well as any in vivo analysis of its 5’-flanking region. With the present study we addressed these issues by developing a set of qPCR allele specific primers for MdACS1 and by a functional characterization of the MdACS1 promoters by transient expression analysis. qPCR analysis on different apple tissues and stages of development demonstrated that MdACS1-2 allele is never express and that MdACS1-1 allele is ripening-related and expresses predominantly but not exclusively in apple fruit. To test MdACS1 promoter in fruit the only protocol available in literature for transient transformation of apple fruit was evaluated and optimized. Twenty chimeric promoter::reporter constructs were generated and analyzed by Agrobacterium-transient transformation. The in vivo analysis allowed to identify an enhancer-like region of 261 bp in MdACS1 promoter and a region of 57 bp in MdACS1-2 responsible, also if not alone, in the inactivation of the MdACS1-2 allele. Through the assessment of ethylene production in a segregating progeny derived from the cross between Fuji and Mondial Gala (homozygous for MdACS1-2 allele) we demonstrated that at least two other genes may be involved in apple ethylene production. An hypothesis that could explain the difference between Fuji and Mondial Gala have been proposed.

Tipologia del documento
Tesi di dottorato
Granozio, Serena Maria
Dottorato di ricerca
Scuola di dottorato
Scienze agrarie
Settore disciplinare
Settore concorsuale
Parole chiave
Ethylene biosynthesis, MdACS1, transient gene expression
Data di discussione
9 Aprile 2013

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