Figure 5. Metazachlor alters auxin distribution during root bending partly through the auxin efflux carrier PIN2.

(a,b) Dynamic auxin redistribution 60 min after a gravistimulation, visualized by DII-venus fusion, shows differential auxin distribution in untreated roots (a) with a higher concentration of auxin at the upper side of the root (a), whereas metazachlor-treated roots do not display this differential repartition of auxin after gravistimulation. (b,c) Quantification of signal intensities between the upper and lower side of gravistimulated roots clearly results in a highly significant difference (n=10 seedlings for each experiment over 3 biological replicates). (d–g) The auxin efflux carrier mutant pin2-^eir1 (d,e) and the auxin influx carrier mutant aux1-21 (f,g) show similar phenotype in untreated roots (d,f) (n=110 root per genotype over 3 biological replicates). In metazachlor-treated roots, the pin2-^eir1 mutant (e) appears more resistant to metazachlor than the aux1-21 mutant (g) (n=110 roots per genotype over 3 biological replicates). Statistics were done by two-sided Welch's two sample t-test, ***P-value<0.001. All scale bars, 10 μm.