Xyloglucan Endotransglycosylase Activity Increases during Kiwifruit (Actinidia deliciosa) Ripening (Implications for Fruit Softening)

摘要: The activity of xyloglucan endotransglycosylase (XET) was as-sayed in three tissue zones kiwifruit (Actinidia deliciosa [A. Chev.] C.F. Liang et A.R. Ferguson var cv Hayward) at harvest and several softening stages following a postharvest ethylene treatment. At harvest, extractable XET per unit fresh weight the inner pericarp (IP) core 4.5 42 times higher, respectively, than outer (OP). Within 24 h treatment there an increase specific all tissues that continued throughout softening. Activity increased most OP, where it showed 12-fold rise 6 d after compared with 4.5- 2.5-fold increases IP tissues, respectively. Visible swelling cell wall each observed first detectable pronounced which greatest percentage activity. Xyloglucan, galactoglucomannan, materials isolated purified from OP were tested as donor substrates for XET. enzyme against but inactive galactoglucomannan. active unripe ripe fruit, swollen walls latter being better substrate. results indicate may have key role early fruit ripening, loosening preparation further modification by other wall-associated enzymes.