Identification of Ethylene-Mediated Protein Changes during Nodulation in Medicago Truncatula Using Proteome Analysis

Date

2006

Authors

Prayitno, Joko
Imin, Nijat
Rolfe, Barry
Mathesius, Ulrike

Journal Title

Journal ISSN

Volume Title

Publisher

American Chemical Society

Abstract

Ethylene has been hypothesised to be a regulator of root nodule development in legumes, but its molecular mechanisms of action remain unclear. The skl mutant is an ethylene-insensitive legume mutant showing a hypernodulation phenotype when inoculated with its symbiont Sinorhizobium meliloti. We used the skl mutant to study the ethylene-mediated protein changes during nodule development in Medicago truncatula. We compared the root proteome of the skl mutant to its wild-type in response to the ethylene precursor aminocyclopropane carboxylic acid (ACC) to study ethylene-mediated protein expression in root tissues. We then compared the proteome of skl roots to its wild-type after Sinorhizobium inoculation to identify differentially displayed proteins during nodule development at 1 and 3 days post inoculation (dpi). Six proteins (pprg-2, Kunitz proteinase inhibitor, and ACC oxidase isoforms) were down-regulated in skl roots, while three protein spots were up-regulated (trypsin inhibitor, albumin 2, and CPRD49). ACC induced stress-related proteins in wild-type roots, such as pprg-2, ACC oxidase, proteinase inhibitor, ascorbate peroxidase, and heat-shock proteins. However, the expression of stress-related proteins such as pprg-2, Kunitz proteinase inhibitor, and ACC oxidase, was down-regulated in inoculated skl roots. We hypothesize that during early nodule development, the plant induces ethylene-mediated stress responses to limit nodule numbers. When a mutant defective in ethylene signaling, such as skl, is inoculated with rhizobia, the plant stress response is reduced, resulting in increased nodule numbers.

Description

Keywords

Keywords: albumin; albumin 2; ascorbate peroxidase; cyclopropanecarboxylic acid derivative; ethylene; heat shock protein; protein CPRD49; protein pprg 2; proteinase inhibitor; serine proteinase inhibitor; trypsin inhibitor; unclassified drug; vegetable protein; art Ethylene; Medicago truncatula; Model legume; Nodulation; Protein identification; Sickle mutant; Sinorhizobium meliloti

Citation

Source

Journal of Proteome Research

Type

Journal article

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2037-12-31