Characterization of b-xylosidase activity in tomato and analysis of its hormonal regulation

BUSTAMANTE CLAUDIA; SOZZI GABRIEL; CIVELLO MARCOS; MARTINEZ GUSTAVO

Villa Carlos Paz

Congreso; XLIV Reunión Anual de SAIB; 2008

SAIB

<!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:-1610611985 1107304683 0 0 415 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman","serif"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES; mso-fareast-language:ES;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; font-size:10.0pt; mso-ansi-font-size:10.0pt; mso-bidi-font-size:10.0pt;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Tomato (Solanum lycopersicum), a fleshy climacteric fruit, has long-served as a model for fruit development and ripening studies. During tomato ripening, significant modifications of the cell wall properties were reported and include both depolymerisation and solubilisation of polyuronides and depolymerisation of hemicelluloses. β-xylosidases are enzymes involved in the breakdown of xylans and/or arabinoxylans. In this work, we study the β-xylosidase activity during ripening of wild type (Rutgers and VF36), mutant (rin, nor and nr) and ACC-synthase antisense fruits. We also analyze the possible COOH-terminal processing of the primary translation products of LeXyl1 and LeXyl2 isoenzymes. By using the pericarp disc system from wild type and ACC-synthase antisense fruits, we evaluate the effect of ethylene and other biological regulators on β-xylosidase activity. Our results demonstrate that β-xylosidase activity would be negatively regulated by ethylene and positively regulated by auxins and gibberellins, whereas abscisic acid would not affect it.