title: Molecular cloning and characterization of two novel genes from hexaploid wheat that encode double PR-1 domains coupled with a receptor-like protein kinase.
abstract: Hexaploid wheat (Triticum aestivum L.) contains at least 23 TaPr-1 genes encoding the group 1 pathogenesis-related (PR-1) proteins as identified in our previous work. Here, we report the cloning and characterization of TaPr-1-rk1 and TaPr-1-rk2, two novel genes closely related to the wheat PR-1 family. The two TaPr-1-rk genes are located on homoeologous chromosomes 3D and 3A, respectively, and each contains a large open reading frame (7385 or 6060 bp) that is interrupted by seven introns and subjected to alternative splicing (AS) with five or six isoforms of mRNA transcripts. The deduced full-length TaPR-1-RK1 and TaPR-1-RK2 proteins (95% identity) contain two repeat PR-1 domains, the second of which is fused via a transmembrane helix to a serine/threonine kinase catalytic (STKc) domain characteristic of receptor-like protein kinases. Phylogenetic analysis indicated that the two PR-1 domains of the TaPR-1-RK proteins form sister clades with their homologues identified in other monocot plants and are well separated from stand-alone PR-1 proteins, whereas the STKc domains may have originated from cysteine-rich receptor-like kinases (CRKs). Reverse-transcriptase-PCR analysis revealed that the TaPr-1-rk genes are predominantly expressed in wheat leaves and their expression levels are elevated in response to pathogen attack, such as infection by barley stripe mosaic virus (BSMV), and also to stress conditions, most obviously, to soil salinity. This is the first report of PR-1-CRK hybrid proteins in wheat. The data may shed new insights into the function/evolutionary origin of the PR-1 family and the STKc-mediated defense/stress response pathways in plants.
authors.affiliation: USDA-ARS, Cereal Crops Research Unit, Fargo, ND, 58102-2765, USA. Shunwen.Lu@ars.usda.gov.
authors.forename: Shunwen
authors.identifier: http://orcid.org/0000-0003-1347-4646
authors.initials: S
authors.lastname: Lu
authors.affiliation: USDA-ARS, Cereal Crops Research Unit, Fargo, ND, 58102-2765, USA.
authors.forename: Justin D
authors.initials: JD
authors.lastname: Faris
authors.affiliation: USDA-ARS, Cereal Crops Research Unit, Fargo, ND, 58102-2765, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Edwards
mesh_terms: D017398:Alternative Splicing; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D023281:Genomics; D007438:Introns; D016366:Open Reading Frames; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D011003:Ploidies; D011487:Protein Conformation; D000072417:Protein Domains; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014908:Triticum / Q000201:enzymology / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D017346:Protein Serine-Threonine Kinases
keywords: Common wheat; Cysteine-rich receptor-like kinase; Pathogenesis-related proteins; Plant defense; Signal transduction pathways; Stress response