Cell wall-bound phenolics in cells of maize (Zea mays, Gramineae) and buckwheat (Fagopyrum tataricum, Polygonaceae) with different plant regenerationabilities

Six different tissue types were used in these studies: both regenerable and nonregenerable calli of different morphotypes of buckwheat (Fagopyrum tata ricum, Polygonaceae) and maize (Zea mays, Gramineae) inbred Pa91 as well as two maize inbred cultures, H99-R and H99-NR. with similar compact (embryog enic-like) structure but different regeneration abilities. The lignin level s measured by the thioglycolic acid method in the lines with different rege neration abilities 3 weeks after subculture were somewhat higher in regener able than in nonregenerable calli. The total amount of wall bound phenolic acids in buckwheat (dicotyledonous plant) was similar to that of maize (mon ocotyledonous plant)? but the maize cell walls contained a much higher prop ortion of esterified phenolic acids than the buckwheat cell walls. The buck wheat had almost equal amounts of ester and ether linked phenolic acids, wh ile the maize cell walls had 90% or more esterified linkages. Much higher a mounts of hydroxycinnamic acids are bound to the cell walls of regenerable compared with the nonregenerable buckwheat and Pa91 calli; ferulic and p-co umaric acids in maize, and ferulic and sinapic acids in buckwheat. Room tem perature alkaline treatment released almost all of the ether linked sinapic acid and about 75-80% of the total etherified ferulic acid from the buckwh eat cell walls without breaking the ether linkages. The hydroxycinnamic aci d contents were very similar in the two maize inbred H99 lines with similar morphology but different plant regeneration potential. These results indic ate that wall bound phenolics, in particular ferulic acid, may be associate d with a certain tissue morphological structure, that is necessary but not sufficient for plant regeneration since additional factors seem to be requi red for morphogenesis in vitro. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.