Figure 5.

The tld1-D mutant is deficient in endogenous IAA and shows reduced sensitivity to exogenous IAA. A to C, Auxin-responsive element DR5:GUS staining. The IAA maximum was reduced at the lamina joint in the second leaf (A, arrows), the unelongated basal internode of a 1-month-old seedling (B, arrows), and the nodes (C, top arrow, second node; bottom arrow, basal node) of tld1-D as compared with the wild type (WT). D, Quantification of free IAA in the lamina joint and unelongated basal internodes of 14-d-old seedlings by GC-MS. Bars with asterisks indicate P < 0.05. FW, Fresh weight. E, Effects of exogenous IAA on lateral root formation. The number of lateral roots per centimeter of adventitious root was counted (n = 60, from at least 20 seedlings). F, qRT-PCR analysis of auxin-responsive gene expression in 1-week-old seedlings treated with 10 μm IAA for the indicated times.