'American Society for Biochemistry & Molecular Biology (ASBMB)'
Abstract
In plants, growth in length by cell elongation is conditioned by
certain substances elaborated in the plant and effective in minute
amounts, thus having the nature of hormones. A number of
simple tests have been worked out which allow of a qualitative
and quantitative determination of the growth-promoting properties
of various substances. With the aid of these biological tests the
native growth substances or auxins have been isolated and a
variety of other substances have been shown to possess growth
activity. At first sight the large number of substances which are
active do not appear to fall within any general classification.
Upon further investigation, however, it becomes clear that there
are certain common structural characteristics, and an analysis
of these provides a first step in attacking the fundamental problem
of the relations between chemical structure and physiological
activity. This relation has in recent years been attacked in a
number of other fields, usually involving physiological processes
in animals. On the other hand, it would appear that plants offer
an exceptionally favorable field for study in that their structures---
and possibly their physiological processes-are somewhat less
complicated. Thus, it has been found possible to differentiate
between some of the steps in the chain of reactions which lead to
cell elongation, so that now it becomes possible to determine the
exact structure required in a substance for the regulation of each
of these steps
