Genetic Analysis Of Nonhost Resistance In Rice And Functional Analysis Of Wheat Gene TaMPK6

Wheat stripe rust caused by Puccinia striiformis f. sp. tritici is one of the major diseasesof wheat. Due to this disease, the yield of wheat has been severely impaired many times since1950and has become an important disease restricting wheat production in China. Theresistant cultivar is the primary means to control wheat stripe rust. But the rapid generation ofnew physiological races leads to the loss of resistance in many resistant cultivars and becomea major problem for the control of wheat stripe rust. Therefore, it is important to breed newwheat cultivars with broad-spectrum resistance.In the research, we study the mechanism of nonhost resistance of rice to wheat stripe rustfrom Histology and Genetics. We also located the nonhost resistance related genes so that wecan clone these genes. Through the function analysis of the gene TaMPK6in wheat, we knowthe importance of TaMPK6in wheat to wheat stripe rust. In all, we discussedthe mechanismof plants to Puccinia striiformis f. sp. tritici in two aspects, which provided the molecularbasis to breed new wheat cultivars which had broad spectrum disease resistance.(1) It is difficult to identify the rice stomata for wheat stripe rust, and a few of the sporescan form substomatal vesicle, or with morphologically abnormal infection structures. Themicroscopy results showed that stripe rust could infect rice mutants and produced all theinfection structures necessary for plant colonization, including haustoria. Some rust infectionsites are remarkably large and many plant cells are colonized, but the number of haustoria wasless than that of wheat. It also produce the hypersensitive response andreactive oxygen by theinfection of Puccinia striiformis f. sp. tritici.;(2) The Nipponbare is resistant to wheat stripe rust and the9311is relatively susceptible.Hybridized the two varieties to construction a genetic group to analysis the QTL genes relatedthe nonhost resistance of rice to wheat stripe rust. Initially located the QTL on the thirdchromosome in rice, which between RM14541and RP135;(3) TaMPK6gene (1217bp), contained a1127bp complete ORF encoding376aminoacids. TaMPK6gene possesses multiple conserved domains with a high homology to barley,Brachypodium, rice, sorghum, corn and other monocots sequence. Phylogenetic analysis alsoshows that TaMPK6in wheat is closer to barley, Brachypodium, rice and other monocots thanArabidopsis, potato. This gene could be induced by low temperature, drought, salt stress, ABA and the infection of the stripe rust in wheat. It proves that TaMPK6may be related tothe resistance to stripe rust、the environment stress, the growth and development in wheat.The gene may regulate the level of JA andET, thereby affecting the resistance responsemediated by these signaling molecules;(4)The TaMPK6silenced wheat could produce spores after inoculated by wheat striperust，and the infection hyphae area are larger than that in control. These results infered that itcouldweaken the resistance of wheat to stripe rust after silencing TaMPK6, which confirmedthat the gene is related to plant disease resistance.