A place in the sun

Despite the importance of auxin for plant growth and development, the details of how auxin is synthesized continue to puzzle plant biologists. Multiple biochemical pathways for the production of auxin have been identified or proposed but the specific function of each pathway and how they intersect is not known. Now, the role of at least one pathway has become clearer.

“When the major photoreceptor for shade avoidance detects neighbors, it triggers the TAA1 pathway resulting in a rapid increase in free auxin, which is transported to sites in the stem where it can participate in the growth response,” explains Chory. “Although we showed earlier that at least two additional biosynthetic routes to auxin exist in Arabidopsis, these other pathways are unable to compensate for the loss of the TAA1-dependent pathway.”

In addition to Yi Tao, researchers who contributed to the study include post-doctoral researcher Lin Li, Ph.D., bioinformatics specialist Fangxin Hong, Ph.D. graduate student Lauren J. Ivans, research assistant Jason Lim, and assistant professor Jeff A. Long, all in the Plant Biology Laboratory at the Salk, postdoctoral researchers Jean-Luc Ferrer, Ph.D., and Florence Pojer, Ph.D., and lab manager Marianne E. Bowman, all in the Jack H. Skirball Center for Chemical Biology and Proteomics at the Salk Institute, professors Karin Ljung, Ph.D., and Göran Sandberg, Ph.D., both at the Umeå Plant Science Centre at the Swedish University of Agricultural Sciences in Umeå, Sweden, graduate student Javier E. Moreno and professor Carlos L. Ballaré, Ph.D., both at the Instituto de Investigaciones Fisiologicas y Ecologicas Vinculadas a la Acricultura in Buenos Aires, Argentina, postdoctoral researcher Youfa Cheng, Ph.D. and assistant professor Yunde Zhao, Ph.D., both in the Division of Biological Sciences at the University of California, San Diego.

The Salk Institute for Biological Studies in La Jolla, California, is an independent nonprofit organization dedicated to fundamental discoveries in the life sciences, the improvement of human health and the training of future generations of researchers. Jonas Salk, M.D., whose polio vaccine all but eradicated the crippling disease poliomyelitis in 1955, opened the Institute in 1965 with a gift of land from the City of San Diego and the financial support of the March of Dimes.