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Auxin promotes GA biosynthesis in the aboveground parts of plants. However, it has not been demonstrated previously that this interaction occurs in roots. To understand the interactions between auxin and GAs in these organs, we treated wild-type pea (Pisum sativum L.) roots with the inhibitors of auxin action, p-chlorophenoxyisobutyric acid (PCIB) and yokonolide B (YkB), and with the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA). These compounds generally downregulatedGAsynthesis genes and upregulatedGAdeactivation genes, and reduced the level of the bioactive GA1. These effects indicate that in pea roots, auxin at normal endogenous levels stimulates GA biosynthesis. We show also that supra-optimal levels of exogenous auxin reduce the endogenous level of bioactive GA in roots, although the effect appears too small to account for the strong growth-inhibitory effect of high auxin levels.

Item Type:	Refereed Article
Keywords:	DELLA, feedback, interaction.
Research Division:	Biological Sciences
Research Group:	Plant biology
Research Field:	Plant physiology
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Grains and seeds
Objective Field:	Grains and seeds not elsewhere classified
UTAS Author:	Weston, DE (Mrs Diana Nahodil)
UTAS Author:	Reid, JB (Professor Jim Reid)
UTAS Author:	Ross, JJ (Associate Professor John Ross)
ID Code:	59935
Year Published:	2009
Web of Science® Times Cited:	17
Deposited By:	Plant Science
Deposited On:	2009-12-23
Last Modified:	2015-02-04
Downloads:	1 View Download Statistics