Figure 1.

AgNO₃ Dampens IAA Responses in Roots.

(A) Silver nitrate and AVG are similarly effective in restoring eto1 mutant phenotypes. Wild-type (Col-0), eto1-1, and eto2-1 seedlings were grown on medium supplemented with various concentrations of AgNO₃ or AVG. Hypocotyls were measured 4 d after transfer of 1-d-old seedlings to the dark (top panels). Primary roots of 8-d-old seedlings were measured after growth under continuous white light (bottom panels). Error bars represent se (n = 12).

(B) Root elongation inhibition response of the wild type (Col-0), aux1-7, ein2-1, and eir1-1 to IAA and 2,4-D in the presence and absence of AgNO₃ or AVG. Primary root lengths of 8-d-old seedlings grown under continuous yellow-filtered light on mock (ethanol)-supplemented medium or medium supplemented with 600 nM IAA or 100 nM 2,4-D with or without 5 μM AgNO3 or 10 μM AVG are shown. Error bars represent se (n ≥ 12).

(C) Silver nitrate decreases IAA-induced DR5-GUS expression. Eight-day-old light-grown wild-type (Col-0) seedlings carrying the DR5-GUS transgene (Ulmasov et al., 1997) were mock treated or treated with 1 μM IAA for 2 h in medium lacking or containing 10 μM AgNO₃ or 10 μM AVG and then stained for GUS activity. Bar = 0.5 mm.

(D) Silver nitrate decreases IAA-induced IAA28myc degradation. Ten-day-old wild-type (Col-0) seedlings carrying the IAA28myc construct (Strader et al., 2008a) were treated for 10 min with the indicated combinations of IAA (top panel), 2,4-D (bottom panel), AgNO₃, and AVG in liquid media. Anti-myc and anti-HSC70 antibodies were used to detect IAA28myc and HSC70 (loading control), respectively, on immunoblots of protein prepared from roots of treated seedlings.