The Molecular Characterization And Function Analysis In Resisting Stresses Of Kinase Gene TaMAPK2B;1and TaMAPK4in Wheat

Mitogen-activated protein kinase (MAPK) cascades are signaling components to beubiquitous and evolutionally conserved in eukaryotes, with typical motif of serine/threonine protein kinase domains. Recent studies have found that MAPK cascadepathway (MAPKKK-MAPKK-MAPK) plays critical roles in transmiting signals bysequentially phosphorylation, thus to be involved in plant growth and development aswell as in a variety of biotic and abiotic stress signaling transduction processes. In thisstudy, using six MAP kinase kinase kinase genes, two MAP kinase kinase genes, and11MAP kinase genes in wheat obtained by bioinformatic technique, their molecularcharacterization and expression patterns under various stress conditions wereinvestigated. By the Agrobacterium–tumefaciens mediated genetic transformationapproach, TaMAPK2B;1and TaMAPK4, two members of the MAPK cascade that areresponse to low-Pi stress, were transformed tobacco. The functions of TaMAPK4inresponding to phosphorus deprivation, nitrogen deprivation, and high salinity wasdetermined by expressing in tobacco. The main results are as follows:1．Based on sequencing the clones in a wheat root subtrative cDNA library thatenriches low-Pi stress responsive genes, one gene referred to TaMAPK1a-1, wasidentified. Homologous analysis was perfromed to identify six wheat MAPKKK genes,two wheat MAPKK genes, and12wheat MAPK genes. The molecular characterizationand expression paterns of above-mentioned genes was analyzed.2．Among the20tested wheat MAPK cascade pathway genes,11membersincluding TaMAPKKK1, TaMAPKKK7, TaMAPK2B;1, TaMAPK3, TaMAPK4,TaMAPK6, TaMAPK9, TaMAPK12, TaMAPK12;1, TaMAPK14, TaMAPK16andTaMAPK17were to be low-Pi responses. Five members including TaMAPKKK;A3,TaMAPK6, TaMAPK12;1, TaMAPK14and TaMAPK16were to be nitrogen deprivationresponses. TaMAPK1, TaMAPK4, TaMAPK6, TaMAPK16and TaMAPK17wereresponses to high salt stress. TaMAPK6, TaMAPK12;1and TaMAPK16were responsesto drought stress. 3．Using the recombinant DNA technology, the binary plasmids fused the sense andanti-sense sequence of TaMAPK2B;1and TaMAPK4were constructed. Transgenictobacco plants that fused the sense and anti-sense sequence of TaMAPK2B;1andTaMAPK4were generated by Agrobacterium–tumefaciens mediated genetictransformation approach.4．With transgenic tobacco lines with sense and anti-sense expressions of TaMAPK4and wild type tobacco plants as materials, the functions of TaMAPK4in mediating plantsto resist stresses such as low-Pi, low-N and high salinity stress were analyzed. Comparedwith the control (wild type) plants, the transgenic lines with sense sense and anti-senseexpression of TaMAPK4showed dramatically variations in plant phenotypic tratis, plantgrowth, fresh and dry weights above stress conditions. Of which, the plants with senseexpression of TaMAPK4showed significantly improvement of growth traits, showingmuch stronger, more fresh and dry weight, and higher ability to scavenge reactionoxygen species (ROS). By contrast, the plants with anti-sense expression of TaMAPK4showed poor growth traits, exhabiting much weaker, less fresh and dry weights, andlower ability to scavenge ROS under above conditions. The results in this current studyclearly demonstrated that TaMAPK4is acting as a key signaling component in resistingstresses of low-Pi, low-N and salt stress and can be used an useful gene resource ingenerating crop germplasm with strong tolerance to aforementioned abiotic stresses.