The Research Of The Role Of EDR1,EDR2 In Plant Resistance

Magnaporthe oryzae (M. oryzae), a hemibiotrophic pathogenic fungus can infect rice (Oryza sativa) and cause rice blast. The mechanisms involved in resistance of rice to blast have been studied extensively. However, it is difficult to investigate interactions between rice and M. oryzae because of the relatively large genome sequence of rice and the diversity of M. oryzae. edr1 and edr2 are mutants resistant to powdery mildews. A. thaliana plants (Col-0, pen2, edr1, edr2, pad4, sid2, nim1,jar1, ein2, edr1/pad4, edr1/sid2, edr1/nim1, edr1/jar1, edr1/ein2, edr2/pad4, edr2/sid2, edr2/nim1, edr2/jar1 and edr2/ein2) were tested for their response to M. oryzae and interaction phenotypes were assessed, which will provide theoretical basis for the mechanism of the resistance to M. oryzae in rice.4-week-old Arabidopsis plants were inoculated with M. oryzae strain Y34. There days later, injected leaves were strained by histochemical staining, so as to observe the accumulation of chemical materials in the leaves. Leaves of infected A. thaliana plants were harvested at 6 days postinoculation (dpi) and examined disease severity (DS) score. To confirm that the phenotype was caused by M. oryzae, the inoculated leaves of susceptible plants were cleared and stained with trypan blue at 7 days postinoculation (dpi).Results showed that Col-0 plants was susceptible to Y34, pen2 and edr1 were more susceptible than Col-0. The susceptibility of edr2 and other mutants in JA/ET single pathway were equivalent to Col-0. pad4 and edr1/pad4, edr2/pad4 were less susceptible than Col-0, while other mutants in SA pathway were resistant to M. oryzae. All above suggested EDR1 may mediate the resistance to M. oryzae in Arabidopsis, and the role of EDR1 may depend on SID2 and NIM1. In addition, the role of EDR2 in the resistance to M. oryzae is not obvious.Previous study showed many lesion mimic mutants displayed resistance to pathogen. EMS was used to mutate the seeds of Arabidopsis, and then some lesion mimic mutants were received. One mutant preformed expanding of disease spot, and the phenotype was similar to that of edr1 after inoculated with M. oryzae. These suggest EDR1 may relate to the mutant genein the regulation of the resistance to M. oryzae in Arabidopsis.In order to further investigate the mechanism of resistance of Arabidopsis to M. oryzae, map based cloning was used to gain the mutant gene. Result showed there was a base change in the sequence of LIN2, which caused an amino acid change. LIN2 encoded coproporphyrinogen III oxidase, a key enzyme in the biosynthetic pathway of chlorophyll and heme. And there was no report about the role of the resistance to M. oryzae. As for the mechanism of the edrl and lin2 in the resistance to M. oryzae is need further investigate.