OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplemental Data OA All Versions of this Article: 148/3/1547    most recent pp.108.127613v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in Plant Physiol. Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Rudrappa, T. Articles by Bais, H. P. Search for Related Content PubMed PubMed Citation Articles by Rudrappa, T. Articles by Bais, H. P. Agricola Articles by Rudrappa, T. Articles by Bais, H. P.

PLANTS INTERACTING WITH OTHER ORGANISMS

Root-Secreted Malic Acid Recruits Beneficial Soil Bacteria^{1,[C],[W],[OA]}

Department of Plant and Soil Sciences (T.R., H.P.B.) and Department of Biological Sciences (K.J.C.), University of Delaware, Newark, Delaware 19716; Delaware Biotechnology Institute, Newark, Delaware 19711 (T.R., K.J.C., H.P.B.); and Departments of Chemistry/Biochemistry and Biology, Texas Tech University, Lubbock, Texas 79409 (P.W.P.)

Beneficial soil bacteria confer immunity against a wide range of foliar diseases by activating plant defenses, thereby reducing a plant's susceptibility to pathogen attack. Although bacterial signals have been identified that activate these plant defenses, plant metabolites that elicit rhizobacterial responses have not been demonstrated. Here, we provide biochemical evidence that the tricarboxylic acid cycle intermediate L-malic acid (MA) secreted from roots of Arabidopsis (Arabidopsis thaliana) selectively signals and recruits the beneficial rhizobacterium Bacillus subtilis FB17 in a dose-dependent manner. Root secretions of L-MA are induced by the foliar pathogen Pseudomonas syringae pv tomato (Pst DC3000) and elevated levels of L-MA promote binding and biofilm formation of FB17 on Arabidopsis roots. The demonstration that roots selectively secrete L-MA and effectively signal beneficial rhizobacteria establishes a regulatory role of root metabolites in recruitment of beneficial microbes, as well as underscores the breadth and sophistication of plant-microbial interactions.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Harsh P. Bais (hbais{at}udel.edu).

^[C] Some figures in this article are displayed in color online but in black and white in the print edition.

^[W] The online version of this article contains Web-only data.

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.108.127613

^* Corresponding author; e-mail hbais{at}udel.edu.

Received August 4, 2008; accepted September 15, 2008; published September 26, 2008.

Related articles in Plant Physiol.:

On the Inside

Peter V. Minorsky
Plant Physiol. 2008 148: 1185-1186. [Full Text]  

This article has been cited by other articles:

				Y. Sawaki, S. Iuchi, Y. Kobayashi, Y. Kobayashi, T. Ikka, N. Sakurai, M. Fujita, K. Shinozaki, D. Shibata, M. Kobayashi, et al. STOP1 Regulates Multiple Genes That Protect Arabidopsis from Proton and Aluminum Toxicities Plant Physiology, May 1, 2009; 150(1): 281 - 294. [Abstract] [Full Text] [PDF]

				S. A. Micallef, M. P. Shiaris, and A. Colon-Carmona Influence of Arabidopsis thaliana accessions on rhizobacterial communities and natural variation in root exudates J. Exp. Bot., April 2, 2009; (2009) erp053v1. [Abstract] [Full Text] [PDF]

				M. L. Biedrzycki and H. P. Bais Root secretions: from genes and molecules to microbial associations J. Exp. Bot., April 1, 2009; 60(6): 1533 - 1534. [Full Text] [PDF]