Effect of fluorophenylalanine on indole-3-acetic acid oxidation in Avena coleoptiles

• Main Authors: Andrew B. Maksymowych, Joseph A.J. Orkwiszewski
• Format: Article
• Language: English
• Published: Polish Botanical Society 2014-01-01
• Series: Acta Societatis Botanicorum Poloniae
• Subjects: auxin oxidation; Avena coleoptile; fluorophenylalanine; phenolic metabolism
• Online Access: https://pbsociety.org.pl/journals/index.php/asbp/article/view/1187

Effects of the amino acid analog D,L-p-fluorophenylalanine on auxin oxidizing activity from Avena saliva cv. Clintford have been examined. Incubation of etiolated Avena coleoptile apices with D,L-p-fluorophenylalanine, previously reported to promote elongation and depress phenolic metabolism, lowers auxin oxidizing activity. Temperature and pH profiles demonstrated that depression of oxidizing activity by D,L-p-fluorophenylalanine occurs over a relatively wide range. Incubation of coleoptiles in media containing L-phenylalanine alone or L-phenylalanine combined with D,L-p-fluorophenylalanine result in oxidizing activities which are, respectively, slightly higher than or restored to control levels. Thus, dark incubation of coleoptiles with D,L-p-fluorophenylalanine results in auxin oxidizing activity which differs from that of control and other treatment groups. Oxidizing activity from D,L-p-fluorophenylalanine pretreated coleoptiles has a Michaelis constant (70 µM) and a maximum velocity (0.200) which are consistently lower than the control constants. These findings provide further clarification of the effects of D,L-p-fluorophenylalanine, on coleoptile elongation and auxin oxidizing activity in etiolated Avena coleoptiles.