INDOLE-3-BUTYRIC ACID (IBA) IS ENHANCED IN YOUNG MAIZE (ZEA-MAYS L) ROOTS COLONIZED WITH THE ARBUSCULAR MYCORRHIZAL FUNGUS GLOMUS-INTRARADICES

Inoculation of maize (Zea mays L.) roots with the mycorrhizal fungus G lomus intraradices resulted in an increase of indole-3-butyric acid (I BA) during early stages of infection compared to control roots. The in crease in IBA was accompanied by an increase of IBA synthetase activit y, but the enzyme activity was also enhanced at later stages of infect ion. No IBA was detected in spores of Glomus, whereas small amounts of indole-3-acetic acid (IAA) were found. The endogenous IBA concentrati on is not important for colonization of roots with the fungus, since t wo other maize varieties with lower IBA content had the same infection rate as the variety with higher IBA content. The increase of IBA in A M-colonized roots was also confirmed in the variety 'Alize'. (C) 1997 Elsevier Science Ireland Ltd.