Using Allium alien monosomic addition lines to study chlorophyll degradation in stored Japanese bunching onion

摘要

Chlorophyll (Chl) degradation and the formation of Chl derivatives in stored leaves of Japanese bunching onion (JBO; Allium fistulosum L., genome FF) were determined to elucidate the mechanism of Chl degradation by using alien monosomic addition lines (AMALs; FF+1A to FF+8A) of JBO from shallot (A. cepa L. Aggregatum group, genome AA). Year-round changes in Chl content in JBO and in the AMALs were also detected over 2 years. The Chl content in FF was significantly influenced by the alien chromosomes from shallot. In particular, the Chl contents of FF+4A or FF+5A, were higher in Winter than in IF, which suggests that chromosomes 4A and 5A from shallot had a larger influence on the formation of Chl than the other chromosomes. Chl contents in FF+3A and FF+5A decreased greatly in the leaves of AMALs and JBO during storage at 25 degrees C, whereas in FF+4A the Chl content was the lowest compared to the control, FF. Chlorophyllide (Chlide) a, C13(2)-hydroxychlorophyll (OHChl) a, pheophorbide a, and pheophytin (Phy) a, as derivatives of Chl a, were present mainly during storage of JBO and the AMALs. Phy a levels increased with Chl degradation, especially in FF+3A, while OHChl a levels in FF and FF+3A showed a decline during storage. In addition, Chlide a levels in all lines diminished during storage. Thus, Chl a may be degraded, in part, through Phy a, as well as Chlide a and OHChl a, in JBO and the AMALs during storage.