Growth regulating effects of phenylacetic acid and p-hydroxyphenylacetic acid on Fucus spiralis L. (Phaeophyceae, Fucales) in axenic culture

Abstract

F. spiralis L. was brought into axenic culture by treatment of young frond tips in saturated calcium hypochlorite solution. In axenic culture the Fugus plants grow mostly with cylindrical thalli, which branch once or twice and remain about 1 cm high for several months. Additions of p-hydroxyphenylacetic acid (p-OHPAA) in a concentration range of 10-7-10-5 M as well as of phenylacetic acid (PAA) in concentraations around 10-7 M could induce normal morphology. Broad and slightly wavy frongs were formed and a growth was induced quite comparable to that in bacteria-infected cultures. As these 2 phenylacetic acids were identified previously in the brown alga Undaria, the current experiments show that p-OHPAA and PAA may be natural growth regulators in brown algae.