The alfalfa (Medicago sativa) TDY1 gene encodes a mitogen-activated protein kinase homolog.
Development of root nodules, specifically induction of cortical cell division for nodule initiation, requires expression of specific genes in the host and microsymbiont. A full-length cDNA clone and the corresponding genomic clone encoding a MAP (mitogen-activated protein) kinase homolog were isolated from alfalfa (Medicago sativa). The genomic clone, TDY1, encodes a 68.9-kDa protein with 47.7% identity to MMK4, a previously characterized MAP kinase homolog from alfalfa. TDY1 is unique among the known plant MAP kinases, primarily due to a 230 amino acid C-terminal domain. The putative activation motif, Thr-Asp-Tyr (TDY), also differs from the previously reported Thr-Glu-Tyr (TEY) motif in plant MAP kinases. TDY1 messages were found predominantly in root nodules, roots, and root tips. Transgenic alfalfa and Medicago truncatula containing a chimeric gene consisting of 1.8 kbp of 5' flanking sequence of the TDY1 gene fused to the beta-glucuronidase (GUS) coding sequence exhibited GUS expression primarily in the nodule parenchyma, meristem, and vascular bundles, root tips, and root vascular bundles. Stem internodes stained intensely in cortical parenchyma, cambial cells, and primary xylem. GUS activity was observed in leaf mesophyll surrounding areas of mechanical wounding and pathogen invasion. The promoter was also active in root tips and apical meristems of transgenic tobacco. Expression patterns suggest a possible role for TDY1 in initiation and development of nodules and roots, and in localized responses to wounding.
Schoenbeck
M A
MA
Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul 55108, USA.
Samac
D A
DA
Fedorova
M
M
Gregerson
R G
RG
Gantt
J S
JS
Vance
C P
CP
D020413:3' Untranslated Regions / Q000235:genetics; D020121:5' Untranslated Regions / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006801:Humans; D007438:Introns; D000455:Medicago sativa / Q000201:enzymology / Q000235:genetics*; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins; D018517:Plant Roots; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D015183:Restriction Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D010940:Plant Proteins; D011994:Recombinant Proteins; C101691:MMK4 protein, Medicago sativa; D020928:Mitogen-Activated Protein Kinases