IMPLICATION OF PERSIMMON FRUIT HEMICELLULOSE METABOLISM IN THE SOFTENING PROCESS - IMPORTANCE OF XYLOGLUCAN ENDOTRANSGLYCOSYLASE

A CUTILLASITURRALDE, I ZARRA, E P LORENCES, Stephen Fry

Research output: Contribution to journalArticlepeer-review

Abstract

Hemicellulosic polysaccharides from persimmon fruit (Diospyros kaki L.) pericarp were extracted from depectinated cell walls with 0.5, 1 and 4 hi KOH at different stages of development: (I) maximal growth corresponding to the first sigmoidal growth phase; (II) cessation of growth corresponding to the la between the first and the second sigmoidal phases; (III) maximal growth corresponding to the second sigmoidal phase; and (IV) cessation of growth when the fruit had reached its maximum size and the change in colour (green to red) had taken place. During fruit development the amount of total hemicelluloses per unit dry mass cell wall decreased twofold. Xyloglucan was present in the three hemicellulosic fractions, and also decreased with fruit age, although its amount relative to other hemicelluloses increased. The amount of xyloglucan was especially high in the hemicelluloses extracted with 4 M KOH, representing more than 50% at stages III and IV. The average molecular mass of xyloglucan increased from stage I through stage II (0.5 M hemicellulosic fraction) or through stage LII (1 and 4 M hemicellulosic fractions) and decreased after that. The xyloglucan endotransglycosylase (XET; EC 2.4.1.-) activity was measured as the incorporation of [H-3]XXXGol (reduced xyloglucan heptasaccharide labelled at position 1 of the glucitol moiety) into partially purified persimmon fruit xyloglucan. XET specific activity increased greatly between stages I and II. The importance of this enzyme during fruit ripening is discussed.

Original languageEnglish
Pages (from-to)169-176
Number of pages8
JournalPhysiologia plantarum
Volume91
Issue number2
Publication statusPublished - Jun 1994

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