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Title: TWO GENETICALLY DISCRETE PATHWAYS CONVERT TRYPTOPHAN TO AUXIN: MORE REDUNDANCY IN AUXIN BIOSYNTHESIS

Author
item COHEN, JERRY - UNIV. MN
item Slovin, Janet
item HENDRICKSON, ANGELA - UNIV. MN

Submitted to: Trends in Plant Science
Publication Type: Review Article
Publication Acceptance Date: 10/15/2003
Publication Date: 10/15/2003
Citation: Cohen, J.D., Slovin, J.P., Hendrickson, A. 2003. Two genetically discrete pathways convert tryptophan to auxin: more redundancy in auxin biosynthesis. Trends in Plant Science. 8 (5): 197-199.

Interpretive Summary: The responses of plant tissue to the stress caused by exposure to high or low temperature conditions are controlled by the interaction of several plant hormones, with auxin being one of the primary signals coordinating a plant response to adverse conditions. To understand the role of auxin in such responses, it is important to understand how auxin is made and how its levels within a plant are established. In this manuscript we make the case for auxin synthesis and amount being regulated by the interplay of several discrete pathways, often with several different genes expressing the important proteins in the pathway. Because auxin is involved in a number of other important processes in plant tissues, including cell expansion, root formation, fruit development, and control of fruit abscission, a clearer understanding of the complexity of how it is made has many potential uses for designing strategies for improvement in both production and storage of many crops. These include vegetable as well as fruit crops, where previous work by us has shown that auxins are critically important for control of ripening. This information should be of interest to molecular biologists, plant breeders, and others interested in development of improved plant varieties by biochemical, genetic or molecular techniques as well as producers, consumers and others interested in the benefits possible through crop genetic enhancement techniques.

Technical Abstract: The answer to the simple question of how plants make auxin has proven to be inordinately complex. Recent in planta studies in Arabidopsis have uncovered additional complexity in auxin biosynthesis. Two distinct pathways from tryptophan to the intermediate indoleacetaldoxime were identified. Genic, as well as functional redundancy, appear to be characteristic for auxin biosynthesis and plants may have evolved many different solutions for making and regulating auxin.