The Preliminary Study Of The Function And Expression Of The Rice MPIC Gene

The gene for gene resistance is an important resistance mechanism for plant to resist path-ogen infection. Rice blast resistance genes Pi2and Pi9have broad spectrum of resistance. The Pi2and Pi9proteins belong to NBS-LRR family. In our early research work, we fused Pi2’s NBS domain and Pi9’s LRR domain by domain swapping and constructed the chimeric gene Pi2/Pi9. The Pi2/Pi9gene activates plant autoimmunity, but the Pi9gene does not. So, we named Pi2/Pi9as MPIC (modifier of Pi9, constitutively).To study the molecular mechanism underlying the autoimmunity activated by MPIC, we did the following studies:(1) Analyzed and compared the rice blast resistance spectra and other phenotypes in MPIC and Pi9transgenic plants;(2) Observed the MPIC and Pi9proteins sub-cellular localization in rice cells;(3) Screened and analyzed the downstream genes activated by the MPIC gene;(4) Cloned and functionally analyzed promoters of several downstream genes.In these studies, we obtained the following results:(1) The MPIC rice plants grow lag and weak. Roots turn black. Leaf sheaths are almost engulfed and are spotted with some lesion mimics;(2) The level of SA and peroxide are elevated in MPIC transgenic plants;(3) The rice blast resistance spectra of MPIC and Pi9rice plants are the same;(4) The MPIC protein is lo-cated predominantly in the nucleus zone whereas the Pi9protein is dispersed overall the cell;(5) A total of13genes specifically expressed in MPIC rice plant were identified. The promoters of six of these13genes were cloned and were further used for the construction of the LUC-fused vectors for transient assay. These results are valuable for further studying the molecular mecha-nism underlying the autoimmunity activated by MPIC.