|Samac, Deborah - Debby|
Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 8/2/1997
Publication Date: N/A
Technical Abstract: Mitogen-activated protein (MAP) kinases are protein serine-threonine kinases occupying the third step in a conserved cascade of protein phosphorylation mediating signal transduction in eukaryotes. Induction and activation of plant MAP kinases have been demonstrated in response to stress, mechanical wounding, and growth regulators. We have cloned from an alfalfa genomic library a gene encoding a MAP kinase homologue. Comparison of the genomic nucleotide sequence with corresponding cDNA clones shows the gene to comprise ten exons spanning approximately 5.5 kilobases. The single major open reading frame predicts a polypeptide of 608 amino acids with a molecular mass of 68.9 kilodaltons, significantly larger than other known plant MAP kinases. RNA message from this gene, TDY1, has a size of approximately 2.3 kb, which is in accordance with the size of the predicted protein. Though the RNA message can be detected in all plant organs tested, ,it is most prevalent in shoot and root meristems and root nodules. Fusion of a 1.8 kilobase region upstream from the putative transcriptional start to the beta GUS reporter gene directs beta GUS expression to the root tip and secondary root primordia, to the nodule meristem and cortex, and to leaf axils and shoot meristems. This is the fifth MAP kinase homologue reported in alfalfa. Although its specific role remains to be determined, its expression pattern in nodule and root meristems is suggestive of a role in cell proliferation. This research is supported in part by NSF grant IBN 9206890.