Auxin is a pivotal plant hormone, usually occurring in the form of indole-3-acetic acid (IAA). However, in maturing pea (Pisum sativum) seeds, the level of the chlorinated auxin, 4-chloroindole-3-acetic acid (4-Cl-IAA), greatly exceeds that of IAA. A key issue is how plants produce halogenated compounds such as 4-Cl-IAA. To better understand this topic, we investigated the distribution of the chlorinated auxin. We show for the first time, to our knowledge, that 4-Cl-IAA is found in the seeds of Medicago truncatula, Melilotus indicus, and three species of Trifolium. Furthermore, we found no evidence that Pinus spp. synthesize 4-Cl-IAA in seeds, contrary to a previous report. The evidence indicates a single evolutionary origin of 4-Cl-IAA synthesis in the Fabaceae, which may provide an ideal model system to further investigate the action and activity of halogenating enzymes in plants.

Item Type:	Refereed Article
Keywords:	auxin, evolution, seed development, legumes
Research Division:	Biological Sciences
Research Group:	Plant Biology
Research Field:	Plant Physiology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Biological Sciences
UTAS Author:	Lam, HK (Mr Alvin Lam)
UTAS Author:	McAdam, SAM (Dr Scott McAdam)
UTAS Author:	McAdam, EL (Dr Erin McAdam)
UTAS Author:	Ross, JJ (Associate Professor John Ross)
ID Code:	100413
Year Published:	2015
Funding Support:	Australian Research Council (DE140100946)
Web of Science® Times Cited:	6
Deposited By:	Plant Science
Deposited On:	2015-05-14
Last Modified:	2017-11-06
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