Characterization of b-xylosidase activity in strawberry fruits

BUSTAMANTE CA, ROSLI HG, CIVELLO PM, MARTÍNEZ GA

PLANT SCIENCE

Elsevier

Lugar: Amsterdam; Año: 2006 vol. 171 p. 497 - 504

0168-9452

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 b-xylosidase (FaXyl1) from Fragaria x 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 b-xylosidases from higher plants. The recombinant protein obtained by over-expressing FaXyl1 in E. coli had b-xylosidase activity against the artificial substrate p-nitrophenyl b-D-xilopyranoside. 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 b-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, wich correlates with a higher b-xylosidase activity in all ripening stages analyzed.