title: Defensin gene family in Medicago truncatula: structure, expression and induction by signal molecules.
abstract: A large gene family encoding the putative cysteine-rich defensins was discovered in Medicago truncatula. Sixteen members of the family were identified by screening a cloned seed defensin from M. sativa (Gao et al. 2000) against the Institute for Genomic Research's (TIGR) M. truncatula gene index (MtGI version 7). Based on the comparison of their amino acid sequences, M. truncatula defensins fell arbitrarily into three classes displaying extensive sequence divergence outside of the eight canonical cysteine residues. The presence of Class II defensins is reported for the first time in a legume plant. In silico as well as Northern blot and RT-PCR analyses indicated these genes were expressed in a variety of tissues including leaves, flowers, developing pods, mature seed and roots. The expression of these genes was differentially induced in response to a variety of biotic and abiotic stimuli. For the first time, a defensin gene (TC77480) was shown to be induced in roots in response to infection by the mycorrhizal fungus, Glomus versiforme. Northern blot analysis indicated that the tissue-specific expression patterns of the cloned Def1 and Def2 genes differed substantially between M. truncatula and M. sativa. Furthermore, the induction profiles of the Def1 and Def2 genes in response to the signaling molecules methyl jasmonate, ethylene and salicylic acid differed markedly between these two legumes.
authors: Donald Danforth Plant Science Center, 975 North Warson Road, St Louis, MO 63132, USA.
authors: Jennifer N
authors: JN
authors: Hanks
authors: Anita K
authors: AK
authors: Snyder
authors: Michelle A
authors: MA
authors: Graham
authors: Rajiv K
authors: RK
authors: Shah
authors: Laura A
authors: LA
authors: Blaylock
authors: Maria J
authors: MJ
authors: Harrison
authors: Dilip M
authors: DM
authors: Shah
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000595:Amino Acid Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D003517:Cyclopentanes / Q000494:pharmacology; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D030561:Databases, Nucleic Acid; D005030:Ethylenes / Q000494:pharmacology; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D046913:Medicago truncatula / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D054883:Oxylipins; D010937:Plant Growth Regulators / Q000494:pharmacology; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D000085:Acetates; D003517:Cyclopentanes; D018744:DNA, Plant; D005030:Ethylenes; D054883:Oxylipins; D010937:Plant Growth Regulators; D018749:RNA, Plant; C072239:methyl jasmonate; C036216:ethylene; D020156:Salicylic Acid