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

Abstract

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.

Genome-wide identification of mitogen-activated protein kinase gene family in Gossypium raimondii and the function of their corresponding orthologs in tetraploid cultivated cotton

“…Previous studies have demonstrated that some MAPK genes exhibit tissue specificity in various plants such as Arabidopsis, tobacco, poplar, Brachypodium distachyon, wheat and Brassica [17,37,[43][44][45][46]. RsMPK2 was detected in vegetative and reproductive organs, with different expression patterns [47].…”

Genome-wide analysis of salinity-stress induced DNA methylation alterations in cotton (Gossypium hirsutum L.) using the Me-DIP sequencing technology

“…Cell signal transduction pathway plays a vital function in generating stress response. The MEKK-MKK-MPK module has been reported and well-studied to be related with signal transduction (Liang et al, 2013). For example, Arabidopsis MPK4 could be phosphorylated by the upstream MKK1/2 to regulate the WRKY transcription factors Qiu et al, 2008).…”

Identification of a novel mitogen-activated protein kinase kinase gene (MKK2) in the oilseed rape Brassica campestris

“…Furthermore, a MAPK cascade is involved in several signal transduction pathways in plants (Hirt et al 1997). For instance, BnaMKK2 is significantly induced by stress conditions, including cold, oxalic acid, salicylic acid, and Sclerotinia sclerotiorum infection (Liang et al 2013). Considering these findings, we examined the effects of salt stress on MKK2 expression.…”

“…For instance, NbMKK1 and ZmMKK4 are localized in the nucleus (Takahashi et al 2007;Kong et al 2011). However, AtMKK4, ZmMKK3, GhMKK5, and BnaMKK2 are observed in both the cytoplasm and the nucleus (Rodriguez et al 2010;Zhang et al 2012a,b;Liang et al 2013). Coronado et al (2002) studied the dynamic changes in MAPK-active forms in plant differentiation and proliferation.…”