Figure 4.

Discrepancy of auxin concentration in pls between modelling and experimental results reveals a role of PLS in auxin biosynthesis (see text for details). (A) Model prediction of auxin concentration in pls, wt and PLSox in response to the application of the ethylene precursor ACC; (B) Experimental demonstration that ACC induces auxin response in wild-type root tips (revealed as DR5∷GFP expression; upper two panels), but the pls mutant shows no DR5∷GFP induction by ACC (lower two panels). The pls mutant (lower left panel) also shows a reduced DR5∷GFP signal compared with wild type (upper left panel) in the absence of ACC treatment, consistent with an experimentally lower auxin concentration in the root tip (Chilley et al, 2006).