beta-xylosidase activity and expression of a beta-xylosidase gene during strawberry fruit ripening.
Strawberry fruit shows a marked softening during ripening and the process is associated with an increment of pectin solubility and a reduction of the molecular mass of hemicelluloses. In this work, we report the activity of beta-xylosidase and the expression of a beta-xylosidase gene in strawberry fruit. We have cloned a cDNA fragment encoding a putative beta-xylosidase (FaXyl1) from a cDNA library obtained from ripe strawberry fruit. The analysis of the deduced amino acid sequence revealed that FaXyl1 is closely related to other beta-xylosidases from higher plants. The expression of FaXyl1 was strongly associated to the receptacle tissue although a low expression level was detected in achenes and ovaries. The accumulation of FaXyl1 mRNA is ripening-related, starting in white fruit, reaching the maximum at 25-50% red fruit and decreasing thereafter. The total beta-xylosidase enzyme activity was detected in all ripening stages with the maximum in 25-50% red fruit. The low activity level detected in immature stages, where no expression of FaXyl1 was found, suggests the presence of other beta-xylosidases-like genes. Both the expression of FcaXyl1 and the total beta-xylosidase activity were down regulated by auxins, as occurs for most of the ripening-related processes in strawberry fruit. A putative role of FaXyl1 and beta-xylosidase is discussed.
Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH) (CONICET-UNSAM), Camino de Circunvalación Laguna Km 6. 7130 Chascomús, Argentina. gmartinez@intech.gov.ar
Gustavo A
GA
Martínez
Alicia R
AR
Chaves
Pedro M
PM
Civello
D000595:Amino Acid Sequence; D044602:Cellulases / Q000235:genetics; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000235:genetics; D031985:Fragaria / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014995:Xylosidases / Q000235:genetics* / Q000378:metabolism*
D018076:DNA, Complementary; D044602:Cellulases; D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase