| Plants have a very complex mechanism of signal transduction, which can perceive different stress signals from their surroundings, transduce them and activate a diverse set of physiological, metabolic and defense systems to survive and to sustain growth. Protein kinases play very important roles in signal transduction, regulateing the growth, development, and gene expression.Protein kinases have been found in majority of eukaryote and procaryotic organism. The catalytic domains of eukaryotic protein kinases are 250~300 amino acids and the protein kinases have 11 conserved subdomains. Based on the substrate specificity, all identified protein kinases have been divided into two major classes: Ser/Thr protein kinases, and tyrosine protein kinases, and a third one have dual specificity for Ser/Thr/tyrosine protein kinases. In addition, Hanks and Hunter have classified protein kinases into five subgroups: the"AGC"group, the"CaMK"group, the"CMGC"group, the"conventional PTK"group and the"other"group. We isolated two protein kinases MAPK1 and W55a, which were cloned from drought-induced Triticum aestivum. (Xiao Baimai) cDNA library. The two protein kinases are all never be reported before. The MAPK1 belongs to the"CMGC"group, while the W55a belongs to the"CaMK"group. The study is to investigate the expression pattern of the new protein kinase genes, MAPK1 and W55a responsive to different stresses through RT-PCR. And to investigate the resistance of two protein kinase genes, we introduced the two genes into tobacco and Arabidopsis, responsively.(1) Analysis of expression pattern: To investigate the expression pattern of MAPK1 and W55a and a internal USP gene W1 responsive to different stresses, total RNA were extracted and purified from T. aestivum which were subjected to various stress treatments (eg. drought, low temperature, high salinity, abscisci acid (ABA), salicylic acid (SA), methyl jasmonate (MeJA) and ethelene (ET)) for different time. The results of RT-PCR analysis indicated that MAPK1 could be induced by drought, low temperature, high salinity, ABA, SA, MeJA and ET, and the W55a could be induced by drought, high salinity, ABA, SA, MeJA and ET except low temperature; the internal gene W1 could be induced by drought, low temperature, ABA, SA and ET except salinity and MeJA. But the expression mode was different. The results showed that MAPK1, W55a and W1 may play different role in different signaling pathways, and the two genes may function as an integrator among multiple defense signaling molecules.(2) Achievement of transgenic tobacco and resistance of salinity: The MAPK1 gene was introduced into tobacco through agrobacterium-mediated transformation, and the leaves of the T0 MAPK1 transgenic tobacco lines were treated in salt stress. The results showed that the MAPK1 gene improved the salt tolerance of transgenic tobacco.(3) Achievement of transgenic tobacco and resistance of drought: The W55a gene was introduced into Arabidopsis through agrobacterium-mediated transformation, and the T3 W55a transgenic Arabidopsis lines were treated in mock drought stress. The results showed that the W55a gene improved the drought tolerance of transgenic Arabidopsis.(4) The yeast two-hybrid experiment of protein kinse MAPK1 and transcription factor W17: Based on the function domains of the transcription factor W17, we constructed a set of bait carrier. The results indicated that the domain of the W17 gene which interact with MAPK1 and prove MAPK1 could interact with W17.In this study, we analyzed the character and function of MAPK1 and W55a. The results indicated that MAPK1, W55a were induced by abiotic stresses and exogenous hormone treatments. Transgenic tobacco overexpressing MAPK1 could improve the transgenic tobacco tolerance in salt stress; Transgenic Arabidopsis overexpressing W55a could improve the transgenic Arabidopsis tolerance in mock drought stress. These provide good candidate gene resources for improving crop tolerance to adverse environmental conditions using gene engineering.
|
PDF Full Text Request