Fig.4

Arabidopsis thaliana (Col-0) were grown hydroponically for 14 days and transferred to nutrient solutions with or without L-DOPA, at pH 5.5 and 6.0. A Pictures of the plants three days after transfer to the different treatments in a representative experiment. DOPA-treated plants appear smaller and darker than control plants that grew without L-DOPA at both pH. The roots and rosettes of plants treated with L-DOPA at pH 6 are smaller than their counterparts from plants treated at pH 5.5. B Fresh weight of rosettes showing the inhibitory effect of L-DOPA on plant growth. The inhibition of rosette size by L-DOPA was exacerbated at pH 6.0. C Ferric chelate reductase (FCR) activities of Arabidopsis roots, which constitutes an estimate of the Fe uptake activity. L-DOPA increased FCR activity at the root surface, regardless of the pH. At pH 6.0, the effect of L-DOPA on Fe reduction by roots was more pronounced. The symbols *, ** and *** indicate statistical significance of P < 0.05, P < 0.01 and P < 0.001 respectively. Results are means of the results of 3 experiments, and error bars correspond to standard deviation (n = 3)