Proteomic approach: Identification of Medicago truncatula proteins induced in roots after infection with the pathogenic oomycete Aphanomyces euteiches

Abstract

The legume root rot disease caused by the oomycete pathogen Aphanomyces euteiches is one major yield reducing factor in legume crop production. A comparative proteomic approach was carried out in order to identify proteins of the model legume Medicago truncatula which are regulated after an infection with A. euteiches . Several proteins were identified by two dimensional gel electrophoresis to be differentially expressed after pathogen challenge. Densitometric evaluation of expression values showed different regulation during the time-course analysed. Proteins regulated during the infection were identified by matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). Among the differentially expressed proteins, two encoded putative cell wall proteins and two were designated as small heat shock proteins. Furthermore, an isoform of the chalcone-O-methyltransferase was found to be increased in infected roots. The majority of induced proteins belonged to the family of class 10 of pathogenesis related proteins (PR10). Previously, various PR10-like proteins have been shown to be regulated by general stress or abscisic acid (ABA). Therefore, these proteins were further investigated concerning their regulation in response to drought stress and exogenous ABA-application. Complex regulation patterns were identified: three of the A. euteiches -induced PR10-like proteins were also induced by exogenous ABA- but none of them is induced after drought stress. In contrast, three of these proteins are down-regulated by drought stress. Hence, the strong expression of different PR10-family members and their regulation profiles indicates that this set of proteins plays a major role during root adaptations to various stress conditions.

Silencing of the Rac1 GTPaseMtROP9inMedicago truncatulaStimulates Early Mycorrhizal and Oomycete Root Colonizations But Negatively Affects Rhizobial Infection

“…3). As reported previously, PR proteins of class 10 (PR-10) represent marker proteins for established A. euteiches infection in M. truncatula (Colditz et al, 2004(Colditz et al, , 2005Schenkluhn et al, 2010). Relative expression of MtPR10-1 is stronger in Mtvector than in MtROP9i roots after A. euteiches infection (Fig.…”

“…Nontransgenic Plant Material, Microbial Infections, and Infection Evaluation M. truncatula (Jemalong A17) seedlings were grown as described previously (Colditz et al, 2004(Colditz et al, , 2005. Inoculation of MtROP9i, Mtvector, and Mtwt plant roots with Aphanomyces euteiches (ATCC 201684) was carried out as described before (Colditz et al, 2007).…”

Rooteomics: The Challenge of Discovering Plant Defense-Related Proteins in Roots

“…In contrast, the study of proteins differentially expressed in response to root pathogens is a neglected area of proteomics. Only few investigations were carried out on altered protein composition induced by root pathogens [34,55,56]. Most of these studies have used a 2-DE approach followed by in-gel trypsin digestion and MALDI-TOF MS and several proteins have been identified.…”

“…By using 2-DE, the root protein profiles of M. truncatula after Aphanomyces euteiches pathogen infection were analyzed [55]. Several differentially expressed proteins in response to the infection were identified by MALDI-TOF-MS and the majority of the induced proteins belonged to the family of the class 10 of PR proteins.…”

Proteomic studies of arbuscular mycorrhizal associations

“…Due to the lack of a detailed database and to the identification method used, based on Edman N-terminal sequencing, only one of these proteins was identified as an AM down regulated vacuolar H + -ATPase. Medicago truncatula has been adopted as a model species for microbe-plant mutualism, and it already had more than 190,000 expression sequence tags available at 2004 [81]. The methods of phenol extraction, TCA/acetone precipitation and methanol/chloroform fractioning were compared for this plant species [82], and phenol extraction was shown to be the most efficient method for the extraction of soluble proteins for 2DE.…”