With this topic, we will cover emerging knowledge on the roles played by polyamines in the control of plant growth, development, responses to the biotic environment, and stress mitigation. Polyamines are small, amine-containing, organic bases that have been found in all living systems. Taking mostly a cationic form under physiological pH, polyamines have long been proposed to play an important structural role through their interactions with cellular anionic molecules such as nucleic acids, proteins or phospholipids. However, more recent studies have suggested a direct contribution of polyamines in the control of a variety of cellular processes, including cell division, expansion, differentiation and death, DNA, RNA and protein synthesis, chemiosmosis, and enzyme or channel activity.

In plants, the abundance of several polyamines correlates with cell proliferation and stress response. Their steady state is tightly controlled at the level of their synthesis, conjugation to proteins and hydroxycinnamic acid, catabolism, and transport. Importantly, products of their catabolism such as H2O2 and GABA, other downstream signaling molecules such as NO, or conjugated forms have also been found to contribute to complex signaling pathways that interact with hormonal signaling to modulate environmental stress response. Defined polyamines and their derivatives also appear to regulate organogenesis, embryogenesis, vasculature, leaf, flower and root development, root branching, floral initiation, photosynthesis, programmed cell death, pollen tube growth, and fruit development and ripening. Additionally, in some plant species, polyamines have been found to function as precursors in the biosynthesis of secondary compounds that contribute to plant defense and may also have interesting pharmacological properties.

Recent attempts at incorporating strategies from systems biology, genetics, cell biology, biochemistry and physiology to study the multiple functions of polyamines in plants have yielded important new insights into their molecular modes of action. This topic will encourage contributions from scientists with expertise in different disciplines investigating the molecular roles, both general and compound-specific, of distinct polyamines, their conjugation and catabolism derivatives, and downstream signaling molecules, in the control of plant growth, development and response to their environment. We hope that this compilation of reviews and research papers on polyamines will foster discussions within the field, promote collaborations, and provide the basic information needed for downstream translational research, including the development of stress-tolerant crops, or engineering secondary pathways that lead to the synthesis of compounds with interesting pharmacological properties, potentially useful as drugs.

Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.