Histological and Histochemical Changes in Developing and Ripening Peaches. II. The Cell Walls and Pectins

Abstract

REEVE, R. M. (V.S.D.A., Albany, California.) Histological and histochemical changes in developing and ripening peaches. II. The cell walls and pectins. Amer. Jour. Bot. 46(4): 241-247. Illus. 1959.-Histological and histochemical observations on developing and ripening clingstone and freestone peaches have revealed that, after cell divisions have ceased in the meso carp, cell wall thickening and cell enlargement in the mesocarp parenchyma increase until the fruit is nearly full cell size. The cell walls then decrease in thickness as the fruit ripens and softens. Degree of methyl esterification of the pectic substances, as estimated histochemically, remains at about 75--80% in immature fruits during their cell-enlargement phase of growth. Percent of methyl esterification apparently is much lower, or amounts of esterified pectates are very low during the meristematic phases of fruit growth. Just prior to ripening, degree of esterification increases and approaches 100% in hard, ripe fruit at about the same time that the parenchyma cell walls exhibit their greatest thickness or degree of hydration. The degree of esterification of the pectic substances then rapidly decreases and the cell walls become appreciably thinner as the ripening fruit softens. Further relation of these changes in wall thickness, in degree of esterification of the pectins, and in other cell wall carbohydrates to the textural qualities of ripening fruits is discussed. Interpretations concerning cell wall plasticity, cell growth and relation between auxin and changes in pectins also are presented.

Postharvest Variation in Cell Wall-Degrading Enzymes of Papaya (Carica papaya L.) during Fruit Ripening

“…PME is believed to have little effect on wall softening (7,20) serving only to cause partial demethylation allowing PG activity. This deesterification has occurred with the loss of galactose and arabinose side branches from pectins during fruit ripening (1,18,24). Papaya PME activity increased gradually during fruit ripening (Fig.…”

Cytology and Biochemistry of Pathogenic Growth of Botrytis cinerea Pers. in Apple Fruit

“…Estrifaction of pectic substances in apple fruit was determined by a method whiA is a modification of the method described by REEVE (1959). Instead of measuring the light reflection from tLssue slices treated with hydroxylamin and ferric dilorlde, we extracted by acid the ferric ions whldi become bound to the tissue by this procedure, and measured colorimetrically the ferric ion concentration in the extract by reaction with salicylic acid.…”

Pectin Methyl Esterase in the Ripening Banana

“…The changes in pectic substances of plant tissue that occur during ripening and maturation are undoubtedly of considerable importance to texture. Many investigators have studied changes in pectic materials in products such as apples (Woodmansee et al, 1959)) pears (Emmett, 1929 ;McCready and McComb, 1954)) peaches (DeHaan, 1957 ;Postlmayr et al, 1956;Reeve, 1959), tomatoes (Stier et al, 1956;Woodmansee et al, 1959), and oranges (Sinclair and Jolliffe,195s).…”