title: Genome-wide transcriptome and functional analysis of two contrasting genotypes reveals key genes for cadmium tolerance in barley.
abstract: BACKGROUND
  Cadmium (Cd) is a severe detrimental environmental pollutant. To adapt to Cd-induced deleterious effects, plants have evolved sophisticated defence mechanisms. In this study, a genome-wide transcriptome analysis was performed to identify the mechanisms of Cd tolerance using two barley genotypes with distinct Cd tolerance.
  
  
  RESULTS
  Microarray expression profiling revealed that 91 genes were up-regulated by Cd in Cd-tolerant genotype Weisuobuzhi and simultaneously down-regulated or non-changed in Cd-sensitive Dong17, and 692 genes showed no change in Weisuobuzhi but down-regulated in Dong17. Novel genes that may play significant roles in Cd tolerance were mainly via generating protectants such as catalase against reactive oxygen species, Cd compartmentalization (e.g. phytochelatin-synthase and vacuolar ATPase), and defence response and DNA replication (e.g. chitinase and histones). Other 156 up-regulated genes in both genotypes also included those encoding proteins related to stress and defence responses, and metabolism-related genes involved in detoxification pathways. Meanwhile, biochemical and physiological analysis of enzyme (ATPase and chitinase), phytohormone (ethylene), ion distribution and transport (Cd, Na(+), K(+), Ca(2+), ABC transporter) demonstrated that significantly larger Cd-induced increases of those components in Weisuobuzhi than those in Dong17. In addition, Cd-induced DNA damage was more pronounced in Dong17 than that in Weisuobuzhi.
  
  
  CONCLUSIONS
  Our findings suggest that combining microarray, physiological and biochemical analysis has provided valuable insights towards a novel integrated molecular mechanism of Cd tolerance in barley. The higher expression genes in Cd tolerant genotype could be used for transgenic overexpression in sensitive genotypes of barley or other cereal crops for elevating tolerance to Cd stress.
authors.forename: Fangbin
authors.initials: F
authors.lastname: Cao
authors.forename: Fei
authors.initials: F
authors.lastname: Chen
authors.forename: Hongyan
authors.initials: H
authors.lastname: Sun
authors.forename: Guoping
authors.initials: G
authors.lastname: Zhang
authors.affiliation: College of Agriculture and Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou 310058, P,R, China. z.chen@uws.edu.au.
authors.forename: Zhong-Hua
authors.initials: ZH
authors.lastname: Chen
authors.forename: Feibo
authors.initials: F
authors.lastname: Wu
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D002104:Cadmium / Q000494:pharmacology*; D002688:Chitinases / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects; D020869:Gene Expression Profiling; D018745:Genome, Plant; D005838:Genotype; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D001467:Hordeum / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D013312:Stress, Physiological; D059467:Transcriptome / Q000187:drug effects*
chemical_list: D010940:Plant Proteins; D002104:Cadmium; D004247:DNA; D005982:Glutathione Transferase; D002688:Chitinases; D000251:Adenosine Triphosphatases