Figure 2.

Auxin-response mutant defects in lateral root induction by IBA, hypocotyl elongation inhibition by IBA, and root elongation inhibition by ABA. Hormone response of Col-0 (Wt), ibr5-1, tir1-1, tir1-1 ibr5-1, axr1-3, axr1-3 ibr5-1, aux1-7, and aux1-7 ibr5-1 were examined. (A) Lateral roots were counted 4 days after transfer of 4-day-old seedlings to medium supplemented with either 0 (ethanol control) or 10 μM IBA. Primordia emerged from the main root were counted as lateral roots. Error bars represent standard errors of the means (n ≥ 14). tir1 ibr5 had significantly fewer lateral roots in response to IBA than either tir1 or ibr5 (P ≤ 0.001 in two-tailed t-tests assuming unequal variance). (B) Lengths of hypocotyls were measured 4 days after transfer of 1-day-old seedlings to the dark. Error bars represent standard errors of the means (n = 20). tir1 ibr5 hypocotyls were significantly longer than tir1 and ibr5 hypocotyls on 20 or 40 μM IBA (P ≤ 0.0001 in two-tailed t-tests assuming unequal variance). axr1 ibr5 hypocotyls were significantly longer than axr1 and ibr5 on 20 (P ≤ 0.01) or 40 μM IBA (P ≤ 0.001) in two-tailed t-tests assuming unequal variance. (C) Length of primary roots 4 days after transfer of 4-day-old seedlings to medium supplemented with either 0 (ethanol control) or 10 μM ABA. tir1 ibr5 roots were significantly longer than tir1 and ibr5 roots on ABA (P ≤ 0.001) in two-tailed t-tests assuming unequal variance. axr1 ibr5 roots were significantly longer than axr1 and ibr5 roots following control (P ≤ 0.001) or ABA (P ≤ 0.01) treatments in two-tailed t-tests assuming unequal variance. Error bars represent standard errors of the means (n ≥ 14).