UsingAlliumalien monosomic addition lines to study chlorophyll degradation in stored Japanese bunching onion

SummaryChlorophyll (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 FF, 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°C, whereas in FF+4A the Chl content was the lowest compared to the control, FF. Chlorophyllide (Chlide) a, C132-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 alevels increased with Chl degradation, especially in FF+3A, while OHChl alevels in FF and FF+3A showed a decline during storage. In addition, Chlide alevels in all lines diminished during storage.Thus, Chl amay be degraded, in part, through Phy a, as well as Chlide aand OHChl a, in JBO and the AMALs during storage.