Phytochrome induces changes in the immunodetectable level of a wall peroxidase that precede growth changes in maize seedlings.
The regulatory pigment phytochrome induces rapid and opposite growth changes in different regions of etiolated maize seedlings: it stimulates the elongation rate of coleoptiles and inhibits that of mesocotyls.  As measured by a quantitative immunoassay, phytochrome also promotes rapid and opposite changes in the extractable content of a Mr 98,000 anionic isoperoxidase in the cell walls of these same organs: it induces a decrease of this peroxidase in coleoptiles and an increase in mesocotyls.  The peroxidase changes precede the growth changes.  As measured by video stereomicroscopy or a position transducer, red light (R), which photoactivates phytochrome, stimulates coleoptile elongation with a lag of about 15-20 min and suppresses mesocotyl growth with a lag of 45-50 min.  R also induces a 50% reduction in the extractable level of the anionic peroxidase in coleoptile walls in less than 10 min and a 40% increase in the level of this peroxidase in mesocotyl walls within 30 min.  Ascorbic acid, an inhibitor of peroxidase activity, blocks the effects of R on mesocotyl section growth.  These results are relevant to hypotheses that postulate that certain wall peroxidases can participate in light-induced changes in growth rate by their effects on wall extensibility.
Kim
S H
SH
Department of Botany, University of Texas at Austin 78713.
Shinkle
J R
JR
Roux
S J
SJ
D000911:Antibodies, Monoclonal / Q000032:analysis / Q000276:immunology; D002473:Cell Wall / Q000201:enzymology* / Q000378:metabolism / Q000502:physiology / Q000528:radiation effects; D018548:Cotyledon / Q000166:cytology / Q000201:enzymology / Q000254:growth & development / Q000528:radiation effects; D007118:Immunoassay; D008027:Light; D010544:Peroxidases / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D010775:Photic Stimulation; D010834:Phytochrome / Q000378:metabolism*; D018547:Plant Stems / Q000166:cytology / Q000201:enzymology / Q000254:growth & development / Q000528:radiation effects; D013997:Time Factors; D003313:Zea mays / Q000166:cytology / Q000201:enzymology / Q000254:growth & development* / Q000528:radiation effects
D000911:Antibodies, Monoclonal; D010834:Phytochrome; D010544:Peroxidases