The MAP kinase kinase NtMEK2 is involved in tobacco pollen germination.
The tobacco ntf4 mitogen-activated protein (MAP) kinase gene (and its encoded protein p45(Ntf4)) is expressed at later stages of pollen maturation. We have found that the highly related MAP kinase SIPK is also expressed in pollen and, like p45(Ntf4), is activated upon pollen hydration. The MAP kinase kinase NtMEK2 activates SIPK, and here we show that it can also activate p45(Ntf4). In an attempt to inhibit the function of both MAP kinases simultaneously we constructed a loss-of-function mutant version of NtMEK2, which, in transient transformation assays, led to an inhibition of germination in the transformed pollen grains. These data indicate that NtMEK2, and by inference its substrates p45(Ntf4) and/or SIPK, are involved in pollen germination.
University Departments at the Vienna Biocenter, Institute of Microbiology and Genetics, University of Vienna, A-1030 Vienna, Austria.
Viktor
V
Voronin
Tatiana
T
Aionesei
Apinun
A
Limmongkon
Ioulia
I
Barinova
Alisher
A
Touraev
Christiane
C
Laurière
María-José
MJ
Coronado
Pilar S
PS
Testillano
Maria-Carmen
MC
Risueño
Erwin
E
Heberle-Bors
Cathal
C
Wilson
D019943:Amino Acid Substitution; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018525:Germination; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D011058:Pollen / Q000201:enzymology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics; D014867:Water / Q000378:metabolism
D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D014867:Water; D049452:Green Fluorescent Proteins; D005982:Glutathione Transferase; D020929:Mitogen-Activated Protein Kinase Kinases