inducing gene transcription in response to wounding, which may explain why it has a role
in the pathogen defense response.
Jasmonic acid(JA) is a fatty-acid-derived plant hormone that is similar in overall struc-
ture to physiologically active small molecules from animals calledprostaglandins.In
plants, jasmonic acid is firmly associated with pathogen defense pathways. For example,
it has been documented that the physical stimuli of certain insects can trigger the synthesis
of jasmonic acid, which then functions to increase expression of genes involved in
Figure 4.9.Plant hormones. Similarities between some plant and animal hormones. [Reprinted from
Chow and McCourt (2006), with permission from Cold Spring Harbor Laboratory Press.]
102 PLANT DEVELOPMENT AND PHYSIOLOGY