Inhibition of CrWRKY1-overexpressing and empty vector control hairy roots by 4-MT. Hairy roots were grown for 90 d on one-third-strength Schenk and Hilderbrandt medium containing 0 μm (A, CrWRKY1; D, control), 250 μm (B, CrWRKY1; E, control), and 500 μm (C, CrWRKY1; F, control) 4-MT.