title: β-Xylosidase in strawberry fruit: Isolation of a full-length gene and analysis of its expression and enzymatic activity in cultivars with contrasting firmness.
abstract: Strawberry is a non-climateric fleshy fruit, which softens quickly and has short post-harvest life. Ripening is associated with an increment of pectin solubility and a reduction of the content of hemicelluloses. In this work, we have cloned the full-length cDNA encoding a β-xylosidase (FaXyl1) from Fragaria×ananassa and we have characterized its expression in two strawberry cultivars with contrasting fruit firmness. The analysis of the predicted protein showed that FaXyl1 is closely related to other β-xylosidases from higher plants. The recombinant protein obtained by over-expressing FaXyl1 in Escherichia coli had β-xylosidase activity against the artificial substrate p-nitrophenyl β-d-xilopyranoside. Differently from other bifunctional xylosidases, no α-l-arabinofuranosidase activity was detected in the recombinant enzyme. The expression of FaXyl1 gene was analyzed by northern-blot in Camarosa and Toyonaka strawberry cultivars, and compared with the corresponding protein data obtained by Western-blot and with the β-xylosidase activity during ripening. The softest cultivar (Toyonaka) showed an early accumulation of FaXyl1 transcript and a higher expression of the corresponding protein during ripening, which correlates with a higher β-xylosidase activity in all ripening stages analyzed.
authors.affiliation: Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), CONICET-UNSAM, Camino de Circunvalación Laguna Km 6, B7130IWA Chascomús, Argentina.
authors.forename: Claudia A
authors.initials: CA
authors.lastname: Bustamante
authors.affiliation: Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), CONICET-UNSAM, Camino de Circunvalación Laguna Km 6, B7130IWA Chascomús, Argentina.
authors.forename: Hernán G
authors.initials: HG
authors.lastname: Rosli
authors.affiliation: Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), UNLP-CONICET 47 y 116, 1900 La Plata, Argentina.
authors.forename: María C
authors.initials: MC
authors.lastname: Añón
authors.affiliation: Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), CONICET-UNSAM, Camino de Circunvalación Laguna Km 6, B7130IWA Chascomús, Argentina.
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Civello
authors.affiliation: Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), CONICET-UNSAM, Camino de Circunvalación Laguna Km 6, B7130IWA Chascomús, Argentina. Electronic address: gmartinez@intech.gov.ar.
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Martínez
keywords: Cell wall; Fragaria; Ripening; Softening