Genome-wide identification of the mildew resistance locus O (MLO) gene family in novel cereal model species Brachypodium distachyon
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Powdery mildew (PM) is an important plant fungal disease that adversely affects a broad range of angiosperm species, including grass families such as wheat and barley. The MLO (powdery mildew locus O) protein acts as a negative regulator in PM-resistance. Loss-of-function mutation in MLO shows complete resistance to PM disease. In this study, for the first time we reported MLO gene family members in Brachypodium distachyon, model species for grass. 11 well-conserved BdMLO genes were identified on all five chromosomes with a scattered occurrence rather than clustered. The subcellular localization and topology analyses confirmed that all BdMLO proteins anchored to plasma membrane. The seven trans-membrane (TM) and calmodulin-binding domain (CaMBD) sites were well conserved. Amino acid composition showed that BdMLO proteins were leucine-rich (9.9–13.1 %) except BdMLO5 and BdMLO8, which were alanine-rich (10.0 %) and serine-rich (8.7 %), respectively. In silico functional dissection of cis-acting elements revealed that BdMLOs were associated with mainly hormonal, stress, light response and tissue-specific signaling pathways. Phylogenetic relations of BdMLOs within distinct plant species (Arabidopsis, barley, wheat, maize, rice, tomato, pea, pepper and peach) were evaluated. Also, digital expressions of BdMLOs in drought, cold and pathogen infection conditions revealed stress-responsive MLO genes. Phylogenetic and expression analyses provided preliminary evidence that BdMLO2 could be the best susceptibility gene which may play important role in PM resistance. It was concluded that identification and characterization of MLO gene members in Brachypodium will provide essential knowledge for studying full-scale functional analysis of these genes in grass species.
KeywordsMLO gene Powdery mildew Brachypodium distachyon Resistance
Compliance with ethical standards
This article does not contain any studies with human participants or animals performed by any of the authors.
Conflict of interest
Author1 declares that he has no conflict of interest. Author2 declares that he has no conflict of interest.
- Appiano, M., Pavan, S., Catalano, D., Zheng, Z., Bracuto, V., Lotti, C., et al. (2015). Identification of candidate MLO powdery mildew susceptibility genes in cultivated Solanaceae and functional characterization of tobacco NtMLO1. Transgenic Research, 24, 847–858.CrossRefPubMedPubMedCentralGoogle Scholar
- Bai, Y., Pavan, S., Zheng, Z., Zappel, N. F., Reinstädler, A., Lotti, C., et al. (2008). Naturally occurring broad-spectrum powdery mildew resistance in a Central American tomato accession is caused by loss of Mlo function. Molecular Plant-Microbe Interactions, 21(1), 30–39.CrossRefPubMedGoogle Scholar
- Bailey, T. L., Boden, M., Buske, F. A., Frith, M., Grant, C. E., Clementi, L., et al. (2009). MEME SUITE: tools for motif discovery and searching. Nucleic Acids Research, gkp335.Google Scholar
- Chen, Y., Wang, Y., & Zhang, H. (2014). Genome-wide analysis of the mildew resistance locus o (MLO) gene family in tomato (Solanum lycopersicum L.). Plant Omics J, 7(2), 87–93.Google Scholar
- Feechan, A., Jermakow, A. M., Torregrosa, L., Panstruga, R., & Dry, I. B. (2009a). Identification of grapevine MLO gene candidates involved in susceptibility to powdery mildew. Functional Plant Biology, 35(12), 1255–1266.Google Scholar
- Gasteiger, E., Hoogland, C., Gattiker, A., Wilkins, M. R., Appel, R. D., & Bairoch, A. (2005). Protein identification and analysis tools on the ExPASy server. In J. M. Walker, & N. J. Totowa (Eds.), The Proteomics Protocols Handbook (pp. 571–607). Humana Press.Google Scholar
- Kim, M. C., Lee, S. H., Kim, J. K., Chun, H. J., Choi, M. S., Chung, W. S., et al. (2002a). MLO, a modulator of plant defense and cell death, is a novel calmodulin-binding protein isolation and characterization of a rice Mlo homologue. Journal of Biological Chemistry, 277(22), 19304–19314.CrossRefPubMedGoogle Scholar
- Lescot, M., Déhais, P., Thijs, G., Marchal, K., Moreau, Y., Van de Peer, Y., et al. (2002). PlantCARE, a database of plant cis-acting regulatory elements and a portal to tools for in silico analysis of promoter sequences. Nucleic Acids Research, 30(1), 325–327.CrossRefPubMedPubMedCentralGoogle Scholar
- Pasquet, J. C., Chaouch, S., Macadré, C., Balzergue, S., Huguet, S., Martin-Magniette, M. L., et al. (2014). Differential gene expression and metabolomic analyses of Brachypodium distachyon infected by deoxynivalenol producing and non-producing strains of Fusarium graminearum. BMC Genomics, 15(1), 629.CrossRefPubMedPubMedCentralGoogle Scholar
- Punta, M., Coggill, P. C., Eberhardt, R. Y., Mistry, J., Tate, J., Boursnell, C., et al. (2011). The Pfam protein families database. Nucleic Acids Research, gkr1065.Google Scholar
- Singh, V. K., Singh, A. K., Chand, R., & Singh, B. D. (2012). Genome wide analysis of disease resistance MLO gene family in sorghum [Sorghum bicolor (L.) Moench]. Journal of Plant Genomic, 2(1), 18–27.Google Scholar
- Thompson, J. D., Higgins, D. G., & Gibson, T. J. (1994). CLUSTALW: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. Nucleic Acids Research, 22(22), 4673–4680.CrossRefPubMedPubMedCentralGoogle Scholar
- Verelst, W., Bertolini, E., De Bodt, S., Vandepoele, K., Demeulenaere, M., Pè, M. E., & Inzé, D. (2012). Molecular and physiological analysis of growth-limiting drought stress in Brachypodium distachyon leaves. Molecular Plant, sss098.Google Scholar
- Wolter, M., Hollricher, K., Salamini, F., & Schulze-Lefert, P. (1993). The mlo resistance alleles to powdery mildew infection in barley trigger a developmentally controlled defence mimic phenotype. Molecular & General Genetics, 239(1-2), 122–128.Google Scholar