Germination inhibition activity of a naturally occurring lignan from Aegilops ovata L. in green and infrared light

The naturally occurring lignan, monoepoxylignanolide (MEL) from Aegilops ovata L., inhibits germination of lettuce achenes (seeds) in incandescent light but not in the dark. The 'action spectrum' after preincubation of MEL in darkness shows inhibition in the regions of 399 nm and 712-804 nm, but after pretreatment with incandescent light inhibition is seen at 500-577 nm and 712-804 nm. The infrared inhibition by MEL is not reversible by red light. The pretreatment of MEL with incandescent light gives rise to a photoproduct which, together with MEL itself, inhibits the germination of lettuce achenes in the dark.