6-Methoxybenzoxazolinone (MBOA) was found to be present in all plant p
arts of Scoparia dulcis, with the highest concentration being observed
in younger leaves. The content of MBOA in leaves increased with the g
rowth of the plant before bearing fruit. MBOA was also found to be pro
duced by the callus tissues, multiple shoots and hairy roots. The prod
uction of MBOA in the callus tissues was repressed by light irradiatio
n, and cell growth was remarkably inhibited by MBOA.