title: Expression of OsMYB55 in maize activates stress-responsive genes and enhances heat and drought tolerance.
abstract: BACKGROUND
  Plant response mechanisms to heat and drought stresses have been considered in strategies for generating stress tolerant genotypes, but with limited success. Here, we analyzed the transcriptome and improved tolerance to heat stress and drought of maize plants over-expressing the OsMYB55 gene.
  
  
  RESULTS
  Over-expression of OsMYB55 in maize decreased the negative effects of high temperature and drought resulting in improved plant growth and performance under these conditions. This was evidenced by the higher plant biomass and reduced leaf damage exhibited by the transgenic lines compared to wild type when plants were subjected to individual or combined stresses and during or after recovery from stress. A global transcriptomic analysis using RNA sequencing revealed that several genes induced by heat stress in wild type plants are constitutively up-regulated in OsMYB55 transgenic maize. In addition, a significant number of genes up-regulated in OsMYB55 transgenic maize under control or heat treatments have been associated with responses to abiotic stresses including high temperature, dehydration and oxidative stress. The latter is a common and major consequence of imposed heat and drought conditions, suggesting that this altered gene expression may be associated with the improved stress tolerance in these transgenic lines. Functional annotation and enrichment analysis of the transcriptome also pinpoint the relevance of specific biological processes for stress responses.
  
  
  CONCLUSIONS
  Our results show that expression of OsMYB55 can improve tolerance to heat stress and drought in maize plants. Enhanced expression of stress-associated genes may be involved in OsMYB55-mediated stress tolerance. Possible implications for the improved tolerance to heat stress and drought of OsMYB55 transgenic maize are discussed.
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada. jcasaret@uoguelph.ca.
authors.forename: José A
authors.initials: JA
authors.lastname: Casaretto
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada.|University of California, Agriculture and Natural Resources, Cooperative Extension - Kern County, Bakersfield, CA, 93307, USA.
authors.forename: Ashraf
authors.initials: A
authors.lastname: El-Kereamy
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada.
authors.forename: Bin
authors.initials: B
authors.lastname: Zeng
authors.affiliation: Syngenta Biotechnology Inc., Research Triangle Park, NC, 27709, USA.|Expression Analysis, Inc., Durham, NC, 27713, USA.
authors.forename: Suzy M
authors.initials: SM
authors.lastname: Stiegelmeyer
authors.affiliation: Syngenta Biotechnology Inc., Research Triangle Park, NC, 27709, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada.
authors.forename: Yong-Mei
authors.initials: YM
authors.lastname: Bi
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Rothstein
mesh_terms: D055864:Droughts; D018506:Gene Expression Regulation, Plant; D020570:Genes, myb; D059014:High-Throughput Nucleotide Sequencing; D006358:Hot Temperature; D012275:Oryza / Q000235:genetics*; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000235:genetics; D017423:Sequence Analysis, RNA; D013312:Stress, Physiological / Q000235:genetics*; D059467:Transcriptome; D015854:Up-Regulation; D003313:Zea mays / Q000235:genetics / Q000502:physiology*
chemical_list: D010940:Plant Proteins
keywords: Drought; Heat; MYB; Maize; Stress; Zea mays