The stress- and abscisic acid-induced barley gene HVA22: developmental regulation and homologues in diverse organisms.
Abscisic acid (ABA) induces the expression of a battery of genes in mediating plant responses to environmental stresses. Here we report one of the early ABA-inducible genes in barley (Hordeum vulgare L.), HVA22, which shares little homology with other ABA-responsive genes such as LEA (late embryogenesis-abundant) and RAB (responsive to ABA) genes. In grains, the expression of HVA22 gene appears to be correlated with the dormancy status. The level of HVA22 mRNA increases during grain development, and declines to an undetectable level within 12 h after imbibition of non-dormant grains. In contrast, the HVA22 mRNA level remains high in dormant grains even after five days of imbibition. Treatment of dormant grains with gibberellin (GA) effectively breaks dormancy with a concomitant decline of the level of HVA22 mRNA. The expression of HVA22 appears to be tissue-specific with the level of its mRNA readily detectable in aleurone layers and embryos, yet undetectable in the starchy endosperm. The expression of HVA22 in vegetative tissues can be induced by ABA and environmental stresses, such as cold and drought. Apparent homologues of this barley gene are found in phylogenetically divergent eukaryotic organisms, including cereals, Arabidopsis, Caenorhabditis elegans, man, mouse and yeast, but not in any prokaryotes. Interestingly, similar to barley HVA22, the yeast homologue is also stress-inducible. These observations suggest that the HVA22 and its homologues encode a highly conserved stress-inducible protein which may play an important role in protecting cells from damage under stress conditions in many eukaryotic organisms.
Shen
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Department of Biology, Washington University, St. Louis, MO 63130, USA.
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D000040:Abscisic Acid / Q000494:pharmacology*; D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D047390:Casein Kinase II; D017124:Conserved Sequence; D003517:Cyclopentanes / Q000494:pharmacology; D002523:Edible Grain / Q000235:genetics; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics*; D005875:Gibberellins / Q000494:pharmacology; D001467:Hordeum / Q000235:genetics*; D008969:Molecular Sequence Data; D054883:Oxylipins; D010766:Phosphorylation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D012639:Seeds / Q000235:genetics / Q000254:growth & development; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D014018:Tissue Distribution; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000187:drug effects
D003517:Cyclopentanes; D005875:Gibberellins; D054883:Oxylipins; D010940:Plant Proteins; D012333:RNA, Messenger; D012965:Sodium Chloride; C011006:jasmonic acid; D000040:Abscisic Acid; C007842:gibberellic acid; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases