Functional Characterization Of Two GTP Binding Protein Genes, TaRab7and TaTypA, Which Are Involved In Wheat Defense Against Stripe Rust Fungus

Wheat stripe rust fungus, Pucinia striiformis f. sp. tritici (Pst), is one of the mostdevastating pathogens of wheat, causing significant yield loss in wheat production worldwide.One of the most effective methods to control stripe rust is the use of resistant wheat cultivars.Comprehending molecular mechanisms of interactions between wheat and the stripe rustpathogen is important to the rational use of resistance genes in the improvement of cultivars.Therefore, cloning genes related to the interactions between them, along with their expressionpattern and functional analyses could help to illu minate the mechanism of host-pathogeninteractions and provide solid foundation for wheat resistance breeding and modification.GTP-binding proteins function as regulators of specific intercellular fundamentalbiological process. It controls a wide range of cellular activities, from the release of hormones,activation or repression of gene transcription to integrated cellular decisions of proliferation,differentiation, survival or death. A small GTP-binding protein Rab7gene and tyrosinephosphorylated protein A (TypA) from cDNA library of incompatible interaction betweenwheat and Pst were selected from this study. To further understand the molecular mechanismand their function in the interaction of stripe rust fungus and wheat bioinformatics andexpression analysis were performed, and conducted a preli minary characterization of thefunction by VIGS technique. The main contents and conclusions are as follows:The expression of TaRab7was induced by Pst. The expression patterns results revealedthatTaRab7was up regulated after inoculation with CYR23and CYR31. However, theinduced expression in incompatible interaction was higher than that of compatible interaction.The transcription level of TaRab7was also highly induced by environmental stress stimuli.The results of real-time PCR showed that the transcription profile of TaTypA, which wassteady in the compatible interaction; whereas in the incompatible interaction it wasdown-regulated before24h and became up-regulated in the later stage. It was speculated thatthe transcription of TaTypA, as a translational regulator of the stress-responsive proteinsinvolved in ROS, was induced in the interaction of stripe rust fungus and wheat. In addition, we conducted a preliminary functional characterization of the TaRab7andTaTypA using VIGS technique. In this study, the expression TaRab7and TaTypA in wheatwas suppressed effective. Compared with the control group, a small amount of stripe rustspores heaped at injection site,this showed that wheat resistance to stripe rust CYR23significantly weakened after TaRab7or TaTypA gene being silenced. It inferred that TaRab7and TaTypA gene play an important role in some degree of regulation during the interaction ofwheat and stripe rust fungus.