Different responses of shoot and root cultures of Glehnia littoralis to yeast extract

Differentiated shoot and root cultures of Glehnia littoralis were examined for organ-specific responses to yeast extract (YE). Growth, and changes in phenylalanine ammonia-lyase (PAL, EC 4. 1. 3. 5) activity, as well as furanocoumarin and simple phenylpropanoid production were then determined. YE affected root growth positively but negatively affected the growth of both the leaf and petiole. PAL activity was induced in all organs and reached a maximum after 2 days of treatment, though the activity in leaves was about three times higher than that in roots. A large amount of p-coumaric acid (p-CA) was transiently excreted into the culture medium of leaves, which has only been rarely reported to date. Subsequently, bergapten and xanthotoxin appeared in the medium. In contrast, no furanocoumarin was detected in the root cultures throughout the course of treatment. Changes in simple phenylpropanoid contents such as p-CA, caffeic acid (CafA) and ferulic acid (FA) in tissues were analyzed in three forms, i.e., free, soluble-conjugated and insoluble-conjugated forms. In leaves, little difference between control and YE-treated tissues was found except free p-CA, but every form of simple phenylpropanoid was increasingly elicited in the roots. These results indicate that YE acts bi-functionally on the root as a nutrient and an elicitor, but only as an elicitor in the leaf.