Phenotype Analysis Of Mpk9 And Construction Of Mpk9/mpk17 Double Mutant In Arabidopsis Thaliana

Mitogen-activated protein kinases (MAPKs) are the serine/threonine protein kinases in eukaryotes. MAPKs are components of the MAPK cascades and involved in the transduction of extracellular signals to intracellular targets and regulation of special genes expression. MAPK cascades are regulated by different extracellular stimuli and are implicated in a wide variety of biological processes. It mediates the signal transduction involved in plant hormones, biotic and abiotic stresses, such as an important factor directly involved in signaling and regulation of cells in various metabolic processes and ultimately affect plant growth and development. But these two important signaling mechanisms of the interaction are not clear. Therefore, study on how plant MAP kinases are involved in signal transduction and gene expression will be beneficial to understanding and controlling plant growth and development.Currently several identified MPKs belong to TEY subtype; the TDY subtypes are reported rarely in Arabidopsis thaliana. Our laboratory has worked on a TDY subtype's transposon insertion mutant mpkl7 and carried out a series of hormonal treatment, but the phenotype showed no significant difference between mutant and wild-type. This might be that homologous genes are complementary with MPK17 gene in function or MPK17 gene is redundancy, since the sequences of MPK9 and MPK17 gene are highly homologous. To this end, the current study carried out follow experiments, one was to identify the phenotype of mpk9 under different conditions to explore the physiological function of MPK9 gene; another one was to construct mpk9lmpkl7 double mutant by means of hybridization to explore the function of MPK9 and MPK17 genes. The main results obtained are as follows:1. Antibiotic resistance, PCR and RT-PCR methods were successfully used to screened and identified mpk.9 and mpkl7 T-DNA insertion homozygous mutant. 2. mpk9 mutant in plant hormones, abiotic stress and light treatments. Under IAA, NAA,2,4-D and TIBA treatment, root length of Col and mpk9 changes with the concentration of reagents, but no significant differences between wild type and the mutant. Under abiotic stress treatment, low salt promoted root growth, but high salt inhibited the growth of root length, and no difference between Col and mpk9. Under starvation treatment, it showed significant difference between Col and mpk9, and mpk9 showed resistance to starvation. Dark treatment inhibited root length elongation of Col and mpk9, but no difference between Col and mpk9; under red light treatment, root length of mpk9 showed longer than Col, but no difference between Col and mpk9; under blue light treatment it showed significant difference between Col and mpk9, and mpk9 was more resistance to blue light.3. mpk9/mpk17 double mutant was acquired by hybriding T-DNA inserted mutants mpk17 with mpk9 and PCR was used to identify the homozygous double mutant. The phenotype analysis and gene function studies of the constructed double mutant are in progress.