Boyson-Jensen's experiments identified the mechanism of these chemicals, but it was F W Went who first extracted them from avena sativa in agar.  
These chemicals affect gene expression by binding to TIR1, and they leave the cell via PIN proteins.  Examples such as 2,4 -D and 2,4,5 -T are used as selected herbicides and were used in agent orange.  Boyson-Jensen's experiments identified the mechanism of these chemicals, but it was F W Went who first extracted them from avena sativa in agar.  The acid (*) growth model explains their primary function, which is to promote stem elongation.  For 10 points, name this class of plant hormones produced in the apical meristem and that causes apical dominance.
These chemicals affect gene expression by binding to TIR1, and they leave the cell via PIN proteins.  
{Auxin}s