Characterization of some culture factors affecting oxalate degradation by the mycoparasite Coniothyrium minitans

et al. 2013

BMC Genomics

BackgroundEukaryotic mitogen-activated protein kinase (MAPK/MPK) signaling cascades transduce and amplify environmental signals via three types of reversibly phosphorylated kinases to activate defense gene expression. Canola (oilseed rape, Brassica napus) is a major crop in temperate regions. Identification and characterization of MAPK and MAPK kinases (MAPKK/MKK) of canola will help to elucidate their role in responses to abiotic and biotic stresses.ResultsWe describe the identification and analysis of seven MKK (BnaMKK) and 12 MPK (BnaMPK) members from canola. Sequence alignments and phylogenetic analyses of the predicted amino acid sequences of BnaMKKs and BnaMPKs classified them into four different groups. We also examined the subcellular localization of four and two members of BnaMKK and BnaMPK gene families, respectively, using green fluorescent protein (GFP) and, found GFP signals in both nuclei and cytoplasm. Furthermore, we identified several interesting interaction pairs through yeast two-hybrid (Y2H) analysis of interactions between BnaMKKs and BnaMPKs, as well as BnaMPK and BnaWRKYs. We defined contiguous signaling modules including BnaMKK9-BnaMPK1/2-BnaWRKY53, BnaMKK2/4/5-BnaMPK3/6-BnaWRKY20/26 and BnaMKK9-BnaMPK5/9/19/20. Of these, several interactions had not been previously described in any species. Selected interactions were validated in vivo by a bimolecular fluorescence complementation (BiFC) assay. Transcriptional responses of a subset of canola MKK and MPK genes to stimuli including fungal pathogens, hormones and abiotic stress treatments were analyzed through real-time RT-PCR and we identified a few of BnaMKKs and BnaMPKs responding to salicylic acid (SA), oxalic acid (OA), Sclerotinia sclerotiorum or other stress conditions. Comparisons of expression patterns of putative orthologs in canola and Arabidopsis showed that transcript expression patterns were generally conserved, with some differences suggestive of sub-functionalization.ConclusionsWe identified seven MKK and 12 MPK genes from canola and examined their phylogenetic relationships, transcript expression patterns, subcellular localization, and protein-protein interactions. Not all expression patterns and interactions were conserved between canola and Arabidopsis, highlighting the limitations of drawing inferences about crops from model species. The data presented here provide the first systematic description of MKK-MPK-WRKY signaling modules in canola and will further improve our understanding of defense responses in general and provide a basis for future crop improvement.

Section: Introductionmentioning

confidence: 99%

Identification and analysis of MKK and MPK gene families in canola (Brassica napusL.)

Liang

et al. 2013

BMC Genomics

“…Therefore, production of OA by S. sclerotiorum might be an important mechanism for S. sclerotiorum to resist mycoparasitism of C. minitans on hyphae of S. sclerotiorum. Ren et al (2010) reported that the ambient pH value in cultures of S. sclerotiorum was 2.9-3.4 due to production of OA by S. sclerotiorum. However, when cultures of S. sclerotiorum were invaded by C. minitans, the ambient pH value was elevated to 5.7-6.6 due to degradation of OA and/or production of ammonia by C. minitans (Ren et al 2007).…”

Section: Discussionmentioning

confidence: 98%

“…Commercial products of C. minitans including Contans Ò WG (Prophyta Biologischer Pflanzenschutz GmbH, Germany) and KONI Ò (Biovéd Biological Plant Protection Product Producing Co., Kemestaródfa, Hungary) have been developed and registered for control of sclerotinia diseases in several European countries such as Germany, Switzerland, Norway and Hungary, and in the USA. Ren et al (2007Ren et al ( , 2010 reported that C. minitans can degrade OA. This process nullifies the toxic effect of OA on mycelial growth and conidial germination of C. minitans (Wei et al 2004).…”

Section: Introductionmentioning

confidence: 98%

Susceptibility of Sclerotinia sclerotiorum strains different in oxalate production to infection by the mycoparasite Coniothyrium minitans

YongBing

Xie

World J Microbiol Biotechnol

et al. 2011

Three strains of Sclerotinia sclerotiorum, namely Ep-1PB (PB), Ep-1PK (PK) and Ep-1PNA5 (A5), were compared for the production of oxalic acid (OA) on potato dextrose agar (PDA) and Maxwell agar medium (MAM) and for mycelial susceptibility to infection by the mycoparasite Coniothyrium minitans on PDA. Results showed that strain PB produced negligible oxalate, whereas strain PK was detected to produce oxalate, but much less than that produced by strain A5. The three investigated strains differed slightly in mycelial growth rates and mycelial biomass on PDA. However, colonies of strains PB and PK formed on PDA were more susceptible to invasion by C. minitans than colonies of strain A5. Meanwhile, amendment of synthetic oxalate in PDA at 0.25-2.00 mg g -1 medium suppressed aggressiveness of C. minitans in invasion of colonies of S. sclerotiorum strain PB developed on this medium. These results suggest that infection of hyphae of S. sclerotiorum is negatively affected by the presence of oxalate. The importance of oxalate degradation by C. minitans in its mycoparasitism on hyphae of S. sclerotiorum provides a clue for improvement of the biocontrol efficacy of C. minitans in the future.

“…Ren et al (2007) found that C. minitans, the mycoparasite of S. sclerotiorum, can degrade oxalic acid to create a neutral to weakly basic environment necessary for production and the activity of b-1,3-glucanase, which plays an important role in infection of S. sclerotiorum by C. minitans (Giczey et al 2001). Ren et al (2010) further indicated that C. minitans failed to degrade ammonium oxalate (AO) or sodium oxalate (SO) unless the ambient pH of the AO-or SO-containing media was adjusted to be acidic. Meanwhile, C. minitans could hardly degrade oxalic acid when the ambient pH was adjusted to be neutral to weakly basic (Ren et al 2010).…”

Section: Discussionmentioning

confidence: 99%

“…Ren et al (2010) further indicated that C. minitans failed to degrade ammonium oxalate (AO) or sodium oxalate (SO) unless the ambient pH of the AO-or SO-containing media was adjusted to be acidic. Meanwhile, C. minitans could hardly degrade oxalic acid when the ambient pH was adjusted to be neutral to weakly basic (Ren et al 2010). These results suggest that degradation of oxalic acid by C. minitans is pH-dependent.…”

Section: Discussionmentioning

confidence: 99%

Molecular cloning, characterization and expression analysis of a pacC homolog in the mycoparasite Coniothyrium minitans

Han

World J Microbiol Biotechnol

2010

Coniothyrium minitans is a mycoparasite and a promising biocontrol agent of Sclerotinia sclerotiorum, an omniovorous plant pathogenic fungus. Our previous studies indicate that mycoparasitism and antibiosis of C. minitans are greatly affected by ambient pH, implying that a pH-regulatory system may exist in C. minitans. In this study, we cloned a putative pH-responsive transcription factor gene, cmpacC, from strain Chy-1 of C. minitans. The full-length DNA sequence of cmpacC (GenBank Acc. No. FJ176399) has one open reading frame (ORF) and two introns. cmpacC putatively encodes a polypeptide with 596 amino acid residues (GenBank Acc. No. ACN43303). The sequence of this polypeptide has three conserved zinc finger domains. Meanwhile, a 2,740 bp-long 5 0 flanking sequence of cmpacC was obtained. It contains five copies of PacC binding sequences (5 0 -GCCAAG-3 0 ). Real-time RT-PCR analysis indicated that with the increase of ambient pH from 3 to 8, expression of cmpacC, as well as the chitinase gene (cmch1) and the b-1,3-glucanase gene (cmg1), increased consistently in C. minitans. Cloning of cmpacC from C. minitans suggests that the conserved pHdependent signaling pathway might exist in C. minitans. It provides a clue for further deciphering of the pH-regulatory mechanism responsible for the pH-associated interaction between C. minitans and S. sclerotiorum.