ISHS Acta Horticulturae 663: XI Eucarpia Symposium on Fruit Breeding and Genetics
CHARACTERIZATION OF APPLE EXPANSIN SEQUENCES FOR THE DEVELOPMENT OF SSR MARKERS ASSOCIATED WITH FRUIT FIRMNESS |
| Authors: | F. Costa, S. Stella, R. Magnani, S. Sansavini |
| Keywords: | Malus x domestica, fruit ripening, flesh firmness, apple quality, shelf-life, allele specific oligonucleotide, genome walking, microsatellite |
| Abstract:
One of the most evident physiological changes that occurs during ripening of climateric fruits is the modification of cell walls and flesh texture. Several studies carried out on tomato indicate that expansin, a cell wall protein, plays a key role in fruit softening (Rose et al., 1997; Giovannoni, 2001). The related gene member Le-EXP1 is regulated by ethylene, a hormone necessary to induce the ripening process (Rose et al., 2000). To identify an expansin sequence in apple, several heterologous genes of fruit ripening-related expansins, provided by the data base, were aligned using the ClustalW program from the EMBL browser. Degenerated primers designed in the most conserved region amplified a PCR product (Md-EXPa) in a panel of 16 apples cultivars. The amplicons from cvs. ‘Fuji’ and ‘Mondial Gala’ were cloned and sequenced. Fasta analysis indicated a high similarity to the expansin family. To identify polymorphisms between sequences of the two apple cultivars, the 5’-end region of the ‘Mondial Gala’ Md-EXPa was further investigated using a genome walking strategy. This resulted in the identification of a simple sequence repeat (SSR). Two specific primers designed in the flanking region of the SSR motif amplified a polymorphic SSR-marker in 16 apple and two pear genotypes. | |
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