Articles
PHEOPHYTIN FORMATION WITH SENESCENCE IN STORED JAPANESE BUNCHING ONION
Article number
969_25
Pages
189 – 195
Language
English
Abstract
The shelf life of Japanese bunching onion (Allium fistulosum L.; JBO genome FF) leaves diminished with yellowing as a consequence of chlorophyll (Chl) degradation, which seems to be the main factor in yellowing of stored JBO leaves.
The aim of this study was to investigate pheophytin (Phy) formation as a Chl derivative during Chl degradation in stored JBO leaves.
A series of alien monosomic addition lines (AMALs, FF+1A to FF+8A) of JBO, with extra chromosomes from shallot (A. cepa L., Aggregatum group; genome AA) was used as supportive material to study the formation of Chl a derivatives and the activity of Chl-degrading enzymes during storage.
Chl contents in FF+3A and FF+5A decreased greatly during storage at 25°C, whereas in FF+4A the reduction in Chl content was the lowest compared to the control, FF. In JBO leaves, during Chl degradation, the presence of Phy a was prominent as Chl derivatives, which was not recorded in other horticultural crops.
Moreover, the activities of Chl-degrading enzymes, especially Mg-dechelation, also progressively increased during storage at 25°C. The formation of Phy a in stored JBO leaves was further investigated.
By incubating the reaction mixture of crude enzyme extract and Chl a, Phy a was formed by Mg-dechelating action.
Especial significant was the greater formation of Phy a in FF+3A than FF and FF+4A. Electron microscopic observation elucidated the formation of plastoglobules (Pgs) in chloroplasts and its movement from chloroplast to vacuole in JBO. A large number of Pgs in vacuole of FF+3A might relate to the high Phy a formation with Chl degradation.
These findings suggest that Chl a could be degraded in part, through Phy a, and the vacuole along with the chloroplast might be important sites for Chl degradation in JBO during storage.
The aim of this study was to investigate pheophytin (Phy) formation as a Chl derivative during Chl degradation in stored JBO leaves.
A series of alien monosomic addition lines (AMALs, FF+1A to FF+8A) of JBO, with extra chromosomes from shallot (A. cepa L., Aggregatum group; genome AA) was used as supportive material to study the formation of Chl a derivatives and the activity of Chl-degrading enzymes during storage.
Chl contents in FF+3A and FF+5A decreased greatly during storage at 25°C, whereas in FF+4A the reduction in Chl content was the lowest compared to the control, FF. In JBO leaves, during Chl degradation, the presence of Phy a was prominent as Chl derivatives, which was not recorded in other horticultural crops.
Moreover, the activities of Chl-degrading enzymes, especially Mg-dechelation, also progressively increased during storage at 25°C. The formation of Phy a in stored JBO leaves was further investigated.
By incubating the reaction mixture of crude enzyme extract and Chl a, Phy a was formed by Mg-dechelating action.
Especial significant was the greater formation of Phy a in FF+3A than FF and FF+4A. Electron microscopic observation elucidated the formation of plastoglobules (Pgs) in chloroplasts and its movement from chloroplast to vacuole in JBO. A large number of Pgs in vacuole of FF+3A might relate to the high Phy a formation with Chl degradation.
These findings suggest that Chl a could be degraded in part, through Phy a, and the vacuole along with the chloroplast might be important sites for Chl degradation in JBO during storage.
Publication
Authors
P.K. Dissanayake, N. Yamauchi, M. Shigyo, S. Tanaka
Keywords
chlorophyll degradation, Pheophytin a, Allium fistulosum, plastoglobules
Online Articles (41)