Effects Of Cytokinin On The OsAUX1 Regulating Root Development Of Rice (Oryza Sativa L.)

Efficient development of plants is sustained by a root stem that is optimally developed for acquiring water and nutrients. The specification of the root tissues that are responsible for cell proliferation and differentiation is determined by cross-talk between different plate hormones. In recent years, it has been reported the cross-talk between cytokinin and auxin. The researches about the relationship between cytokinin and auxin polar transport are mainly concentrated on how cytokinin regulating the PINs in Arabidopsis. There are little reports about the effection of cytokinin on the auxin polar transporters in rice. We use the osauxl mutants, overexpression materials and other transgene materials which our labotary already have to research the phenotype of the OsAUX1 mutant under the cytokinin treatment.The results are summarized as follows:(1) Under the 0.01μM 6-BA treatment, the primary root length, the root hair length of wild type Dongjin and overexpression line O1 were significantly changed comparing with the mutant. These results show that the OsAUX1 mutants are not sensitive to cytokinin.(2) The transgenitc rice OsAUXlp::GUS and qRT-PCR show that the cytokinin can reduce the expression level of OsAUXs which include OsAUXl.(3) Cytokinin can also downregulate the expression of DR5::GUS and OsCyCB1;1 of wild type and mutants. It implies the phenotype of OsAUX1 mutants under the cytokinin treatment may be related to the auxin level and cell cycle.(4) We analyze the expression level of cytokinin signaling related genes in the osauxl-1 mutant and Dongjin. The cytokinin receptors OsHKs were downregulated in the osaux1-1 mutant comparing with the wild type. After 6-BA treatment, in the osaux1-1 mutant seedlings, OsAHPs, the positive elements in cytokinin signaling were significantly downregulated. And the expression level of type-A OsRRs were not significantly changed comparing with the wild type.(5) We analyze the cytokinin response elements of OsAUXl. OsAUX1 has no cytokinin response elements. It suggests that CRFs do not directly regulate OsAUX1.In conclusion, cytokinin affects the root development via OsAUX1. And there is a potential interaction between OsAUXl and cytokinin signalling components.