Cell wall characteristics associated with the ease of Tabasco pepper fruit detachment
R.A. Arancibia, and C.E. Motsenbocker
Proceedings of 26th International Horticultural Congress. Volume of Abstract . Toronto, Canada, 11-17 August, 2002. Abstract S09-P-158. pp. 261.
2002
บทคัดย่อ
Most cultivated cultivars of pepper (Capsicum sp.) are non-decidous and the pedicel does not separate readily from the fruit. The processing industry wighes to understand how it can harvest fruits without the pedicel. In this study, cell wall characteristics in the detachment zone were examined in two tabasco pepper (C. frutescens) lines which differ in fruit abscission when ripe: ‘Mcllhenny Select’ or easy pick (E) requires a low force to detach from the pedicel when ripe, and ‘Hard Pick’ (H) requires higher force. During ripening the uronide content of tissue extracted from the detachment zone (DZ) was similar in both lines, but pectin depolymerization in water were higher in the E line as the fruit ripened. The degree of pentin esterification (DE) was lower in E in the most mature fruits. The pH measured with a microelectrode in the detachment area showed a high correlation with fruit detachment force (FDF). The pH of the E line decreased faster (from pH 6.4 to pH 4.9) than the H (down to pH 5.5 only) line as the fruit ripened, similar to the FDF. The effect of pH on pollygalacturonase (PG) and cellulase (Cx) activities was also examined. PG and Cx activities from crude extracts increased during ripening but were not different between the two tabasco lines. PG was very active in the range of pH 5.0-5.7 and a half pH unit increase (from pH 5.5 to pH 6.0) reduced the enzyme activity approximately 50%. These results suggest that the DE and applastic pH may affect PG activity and cell wall degradation in vivo.