title: Temporal transcriptome profiling reveals expression partitioning of homeologous genes contributing to heat and drought acclimation in wheat (Triticum aestivum L.).
abstract: BACKGROUND
  Hexaploid wheat (Triticum aestivum) is a globally important crop. Heat, drought and their combination dramatically reduce wheat yield and quality, but the molecular mechanisms underlying wheat tolerance to extreme environments, especially stress combination, are largely unknown. As an allohexaploid, wheat consists of three closely related subgenomes (A, B, and D), and was reported to show improved tolerance to stress conditions compared to tetraploid. But so far very little is known about how wheat coordinates the expression of homeologous genes to cope with various environmental constraints on the whole-genome level.
  
  
  RESULTS
  To explore the transcriptional response of wheat to the individual and combined stress, we performed high-throughput transcriptome sequencing of seedlings under normal condition and subjected to drought stress (DS), heat stress (HS) and their combination (HD) for 1 h and 6 h, and presented global gene expression reprograms in response to these three stresses. Gene Ontology (GO) enrichment analysis of DS, HS and HD responsive genes revealed an overlap and complexity of functional pathways between each other. Moreover, 4,375 wheat transcription factors were identified on a whole-genome scale based on the released scaffold information by IWGSC, and 1,328 were responsive to stress treatments. Then, the regulatory network analysis of HSFs and DREBs implicated they were both involved in the regulation of DS, HS and HD response and indicated a cross-talk between heat and drought stress. Finally, approximately 68.4 % of homeologous genes were found to exhibit expression partitioning in response to DS, HS or HD, which was further confirmed by using quantitative RT-PCR and Nullisomic-Tetrasomic lines.
  
  
  CONCLUSIONS
  A large proportion of wheat homeologs exhibited expression partitioning under normal and abiotic stresses, which possibly contributes to the wide adaptability and distribution of hexaploid wheat in response to various environmental constraints.
authors.affiliation: State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, NO.2 Yuanmingyuan Xi Road, Beijing, Haidian District, 100193, China. liuzhenshan@cau.edu.cn.
authors.forename: Zhenshan
authors.initials: Z
authors.lastname: Liu
authors.affiliation: State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, NO.2 Yuanmingyuan Xi Road, Beijing, Haidian District, 100193, China. mingmingxin@cau.edu.cn.
authors.forename: Mingming
authors.initials: M
authors.lastname: Xin
authors.affiliation: State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, NO.2 Yuanmingyuan Xi Road, Beijing, Haidian District, 100193, China. qjxia1987@126.com.
authors.forename: Jinxia
authors.initials: J
authors.lastname: Qin
authors.affiliation: State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, NO.2 Yuanmingyuan Xi Road, Beijing, Haidian District, 100193, China. penghuiru@cau.edu.cn.
authors.forename: Huiru
authors.initials: H
authors.lastname: Peng
authors.affiliation: State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, NO.2 Yuanmingyuan Xi Road, Beijing, Haidian District, 100193, China. nizf@cau.edu.cn.
authors.forename: Zhongfu
authors.initials: Z
authors.lastname: Ni
authors.affiliation: State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, NO.2 Yuanmingyuan Xi Road, Beijing, Haidian District, 100193, China. yingyin@cau.edu.cn.
authors.forename: Yingyin
authors.initials: Y
authors.lastname: Yao
authors.affiliation: State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, NO.2 Yuanmingyuan Xi Road, Beijing, Haidian District, 100193, China. qxsun@cau.edu.cn.
authors.forename: Qixin
authors.initials: Q
authors.lastname: Sun
mesh_terms: D000064:Acclimatization; D055864:Droughts; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D006358:Hot Temperature; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological; D059467:Transcriptome; D014908:Triticum / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins