title: Transcriptomic analysis of Sorghum bicolor responding to combined heat and drought stress.
abstract: BACKGROUND
  Abiotic stresses which include drought and heat are amongst the main limiting factors for plant growth and crop productivity. In the field, these stress types are rarely presented individually and plants are often subjected to a combination of stress types. Sorghum bicolor is a cereal crop which is grown in arid and semi-arid regions and is particularly well adapted to the hot and dry conditions in which it originates and is now grown as a crop. In order to better understand the mechanisms underlying combined stress tolerance in this important crop, we have used microarrays to investigate the transcriptional response of Sorghum subjected to heat and drought stresses imposed both individually and in combination.
  
  
  RESULTS
  Microarrays consisting of 28585 gene probes identified gene expression changes equating to ~4% and 18% of genes on the chip following drought and heat stresses respectively. In response to combined stress ~20% of probes were differentially expressed. Whilst many of these transcript changes were in common with those changed in response to heat or drought alone, the levels of 2043 specific transcripts (representing 7% of all gene probes) were found to only be changed following the combined stress treatment. Ontological analysis of these 'unique' transcripts identified a potential role for specific transcription factors including MYB78 and ATAF1, chaperones including unique heat shock proteins (HSPs) and metabolic pathways including polyamine biosynthesis in the Sorghum combined stress response.
  
  
  CONCLUSIONS
  These results show evidence for both cross-talk and specificity in the Sorghum response to combined heat and drought stress. It is clear that some aspects of the combined stress response are unique compared to those of individual stresses. A functional characterization of the genes and pathways identified here could lead to new targets for the enhancement of plant stress tolerance, which will be particularly important in the face of climate change and the increasing prevalence of these abiotic stress types.
authors.affiliation: Durham Centre for Crop Improvement Technology, School of Biological and Biomedical Sciences, Durham University, South Road, DH1 3LE Durham, UK. Stephanie.johnson@durham.ac.uk.
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Johnson
authors.forename: Fei-Ling
authors.initials: FL
authors.lastname: Lim
authors.forename: Aliza
authors.initials: A
authors.lastname: Finkler
authors.forename: Hillel
authors.initials: H
authors.lastname: Fromm
authors.forename: Antoni R
authors.initials: AR
authors.lastname: Slabas
authors.forename: Marc R
authors.initials: MR
authors.lastname: Knight
mesh_terms: D018744:DNA, Plant; D055864:Droughts; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D006358:Hot Temperature; D010940:Plant Proteins / Q000235:genetics*; D045868:Sorghum / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D014157:Transcription Factors