Cell Wall Phenolic Content in Tissue Types of Developing Maize Internodes

Elongation and lignification was observed via daily photographs and phloroglucinol-HCI stain on internode 9 (1-9) of growth-chamber grown maize (Zea mays L.) line Mol7 x B73 to correlate internode development with lignification. 1-9 elongated sigmoidally from 8 to 130 mm in 12 days. Lignification began in the upper internode after 3 d and progressed top-down following a basipetal retreat of elongation activity. An improved acetyl bromide method was used to determine UV-absorptive cell wall phenolic concentrations in freeze. dried, ethanol and chloroform:methanol extracted pith parenchyma, pith vascular and rind vascular tissue excised from lower and upper sections of immature, lignifying, and lignified maize 1-9. Pithpnrenchyma and vascular tissue from elongating (immature) internode sections hnd large but variable concentrations of cell-wall phenolics. Pith and rind vascular tissue of post-elongation, lignifying and lignified internodesections had significantly greater cell-wall phenolic concentrations than pith parenchyma.