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Title: AUXIN BIOSYNTHESIS AND METABOLISM.

Author
item NORMANLY, JENNIFER - UNIV. MASS
item Slovin, Janet
item COHEN, JERRY - UNIV. MINN.

Submitted to: Recent Progress in Research on Plant Hormones and Related Substances
Publication Type: Review Article
Publication Acceptance Date: 4/21/2004
Publication Date: 2/14/2005
Citation: Normanly, J., Slovin, J.P., Cohen, J.D. 2005. Auxin biosynthesis and metabolism.. Recent Progress in Research on Plant Hormones and Related Substances. 3rd Edition, pp 36-62.

Interpretive Summary: The growth and development of crop plants is controlled by the action of a number of plant hormones, with the plant hormone auxin central to plant processes from early embryo formation through to fruit ripening. Understanding how plants make and control the levels of this key molecule is critical for the design of new methods for crop improvement and for understanding the action of synthetic plant growth regulators. In this chapter we discuss the recent advances that have been made in understanding how this hormone is made in plants, and how plants control their own development and growth by altering the levels of auxin. This chapter is designed to put recent discoveries in the context of how whole plant processes are determined by this signaling system and how future efforts at plant improvement might be guided by the rapid discoveries that have occurred over the past decade. The information is targeted to graduate students, plant breeders and science professionals in related areas of plant biology.

Technical Abstract: The plant hormone auxin functions are at the intersection between environmental and developmental cues and the response pathways that they trigger. As such, auxin levels can, and should vary dramatically throughout the body and life of the plant, forming gradients that are a central component of its action. Accordingly, plants have evolved intricate regulatory networks with considerable redundancy and adaptive plasticity to maintain the necessary auxin levels for response to changing environmental and developmental signals. The study of auxin homeostasis is aimed at understanding the mechanisms by which plants manage to have the hormone available in the required amount at the right time and place, and at determining how the developmental and environmental signals impact these processes. A combination of molecular genetic and analytical approaches in the past ten years has resulted in an increased understanding of auxin homeostasis; primarily that it involves a highly interactive network of redundant pathways, the complexity of which are only beginning to be discerned. In this chapter, we summarize the growing body of knowledge concerning the enzymes and the genes involved in IAA synthesis and metabolism.