title: RNA-Seq Analysis Reveals MAPKKK Family Members Related to Drought Tolerance in Maize.
abstract: The mitogen-activated protein kinase (MAPK) cascade is an evolutionarily conserved signal transduction pathway that is involved in plant development and stress responses. As the first component of this phosphorelay cascade, mitogen-activated protein kinase kinase kinases (MAPKKKs) act as adaptors linking upstream signaling steps to the core MAPK cascade to promote the appropriate cellular responses; however, the functions of MAPKKKs in maize are unclear. Here, we identified 71 MAPKKK genes, of which 14 were novel, based on a computational analysis of the maize (Zea mays L.) genome. Using an RNA-seq analysis in the leaf, stem and root of maize under well-watered and drought-stress conditions, we identified 5,866 differentially expressed genes (DEGs), including 8 MAPKKK genes responsive to drought stress. Many of the DEGs were enriched in processes such as drought stress, abiotic stimulus, oxidation-reduction, and metabolic processes. The other way round, DEGs involved in processes such as oxidation, photosynthesis, and starch, proline, ethylene, and salicylic acid metabolism were clearly co-expressed with the MAPKKK genes. Furthermore, a quantitative real-time PCR (qRT-PCR) analysis was performed to assess the relative expression levels of MAPKKKs. Correlation analysis revealed that there was a significant correlation between expression levels of two MAPKKKs and relative biomass responsive to drought in 8 inbred lines. Our results indicate that MAPKKKs may have important regulatory functions in drought tolerance in maize.
authors.affiliation: Maize Research Center, Beijing Academy of Agricultural and Forestry Science, Beijing 100097, P.R.China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Maize Research Center, Beijing Academy of Agricultural and Forestry Science, Beijing 100097, P.R.China.
authors.forename: Miaoyi
authors.initials: M
authors.lastname: Zhou
authors.affiliation: School of Life Sciences and School of Advanced Agriculture Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, P.R.China.
authors.forename: Zhaoxu
authors.initials: Z
authors.lastname: Gao
authors.affiliation: Maize Research Center, Beijing Academy of Agricultural and Forestry Science, Beijing 100097, P.R.China.
authors.forename: Wen
authors.initials: W
authors.lastname: Ren
authors.affiliation: Maize Research Center, Beijing Academy of Agricultural and Forestry Science, Beijing 100097, P.R.China.
authors.forename: Fengling
authors.initials: F
authors.lastname: Yang
authors.affiliation: School of Life Sciences and School of Advanced Agriculture Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, P.R.China.
authors.forename: Hang
authors.initials: H
authors.lastname: He
authors.affiliation: Maize Research Center, Beijing Academy of Agricultural and Forestry Science, Beijing 100097, P.R.China.
authors.forename: Jiuran
authors.initials: J
authors.lastname: Zhao
mesh_terms: D000220:Adaptation, Biological; D018533:Biomass; D002874:Chromosome Mapping; D016000:Cluster Analysis; D019295:Computational Biology / Q000379:methods; D055864:Droughts; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D020930:MAP Kinase Kinase Kinases / Q000235:genetics* / Q000378:metabolism; D058977:Molecular Sequence Annotation; D005810:Multigene Family; D009928:Organ Specificity; D010802:Phylogeny; D017423:Sequence Analysis, RNA; D013312:Stress, Physiological / Q000235:genetics*; D059467:Transcriptome; D003313:Zea mays / Q000145:classification / Q000235:genetics* / Q000378:metabolism
chemical_list: D020930:MAP Kinase Kinase Kinases