The Secondary metabolites produced by plants have acquired an important presence in the development of process for special usage in the pharmaceutical, cosmetic, and other industries. In recent years, the usage of plant secondary metabolites has increased, especially for degenerative diseases such as diabetes, cancer, Alzheimer and a numerous of viral infections.

The objective of this special issue is to increase the knowledge of the biotechnology techniques that are being used to produce secondary metabolites in diverse plant species. In vitro systems such as callus and cell suspension cultures can be published as experimental systems for secondary metabolites production. The techniques for genetic modifications and stress biotic and abiotic can be used for the study of the increase production effect of secondary metabolites. The biotic stress such as microorganisms which have interaction either endogenous or exogenous are an important topic to have further research. Abiotic stress such as UV, laser radiation, drought, and heavy metals are also very important.