title: Drought response in the spikes of barley: gene expression in the lemma, palea, awn, and seed.
abstract: The photosynthetic organs of the barley spike (lemma, palea, and awn) are considered resistant to drought. However, there is little information about gene expression in the spike organs under drought conditions. We compared response of the transcriptome of the lemma, palea, awn, and seed to drought stress using the Barley1 Genome Array. Barley plants were exposed to drought treatment for 4 days at the grain-filling stage by withholding water. At the end of the stress, relative water content of the lemma, palea, and awn dropped from 85% to 60%. Nevertheless, the water content of the seed only decreased from 89% to 81%. Transcript abundance followed the water status of the spike organs; the awn had more drought-regulated genes followed by lemma and palea, and the seed showed very little change in gene expression. Despite expressing more drought-associated genes, many genes for amino acid, amino acid derivative, and carbohydrate metabolism, as well as for photosynthesis, respiration, and stress response, were down-regulated in the awn compared with the lemma, palea, and seed. This suggests that the lemma and the palea are more resistant to drought stress compared with the awn.
authors: Department of Biology, University of Northern Iowa, Cedar Falls, IA 50614, USA. Tilahun.Abebe@uni.edu
authors: Tilahun
authors: T
authors: Abebe
authors: Kalpalatha
authors: K
authors: Melmaiee
authors: Virginia
authors: V
authors: Berg
authors: Roger P
authors: RP
authors: Wise
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D050260:Carbohydrate Metabolism / Q000235:genetics; D019069:Cell Respiration / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D055864:Droughts; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D001467:Hordeum / Q000033:anatomy & histology* / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity / Q000235:genetics; D010788:Photosynthesis / Q000235:genetics; D010860:Pigments, Biological / Q000096:biosynthesis; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000235:genetics*; D013223:Statistics as Topic; D013312:Stress, Physiological / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics; D014867:Water / Q000378:metabolism
chemical_list: D000596:Amino Acids; D010860:Pigments, Biological; D014867:Water