Jasmonates, New Regulators of Plant Growth and Development: Many Facts and Few Hypotheses on their Actions

Jasmonates, ubiquitous cyclopentanone compounds, are reviewed as new regulators for plant growth and development. They may complement the group of well‐established “classic” phytohormones. Jasmonates influence a multiplicity of plant physiological processes by inhibition, promotion or induction. In many aspects they are similar to abscisic acid, especially in responses to stress. The review contains information on the chemical structures and metabolism of jasmonates, contributes to their biological role and describes possible mode(s) of action at the level of molecular biology and gene expression. In particular, emphasis is placed on the gene expression and accumulation of jasmonate‐induced abundant polypeptides as a stress response of the plant cells. A hypothesis is attempted in which endogenous jasmonates represent an integral part of the signal transduction chain between stress signal(s) and stress response(s).