Screening Of Magnaporthe Oryzae Lxar Effectors And Functional Study

The filamentous fungus Magnaporthe oryzae causes rice blast, is the most serious disease of cultivated rice. Which can lead to annual rice production losses around the world with the worth of over one billion. The functional analysed LXAR effectors genes of M. oryzae Among the screened effectors are providing new insight into the biological characteristic and molecular pathological mechanism of the fungi and leading to the prospects for sustainable control of rice blast.162 LXAR effectors are recently predicted in the genome of Magnaporthe oryzae by using bioinformatics analysis via computer prediction algorithms. These proteins may be required for virulence in the interaction between host and microbe. To identify whether these LXAR effectors play a role in manipulating plant immunity,45 predicted LXAR effectors are functional assayed by using a PVX-based high-throughput transient plant expression system in Nicotiana benthamiana. The results showed that 14 effectors can block the programmed cell death induced by mouse pro-apoptosis protein BAX in N. benthamiana and 2 effectors can trigger cell death in N. benthamiana, suggesting that M. oryzae LXAR effectors may play an important role in pathogenicity. Furthermore, in order to validate the function of LXAR motif, we mutated LXAR motif of effectors into AAAA, indicating that the LXAR motif is not the only element that is responsible for the effector transfering mechanism. there may be other factors or more complicated mechanism.Elicitors, a group of pathogen secred molecules which can induce host defense response through a certain signal transduction after recognized by plant-receptors on the plasmalemma, played an important role in the plant induced disease resistance. Many LXAR effectors in M. oryzae can suppress hypersensitive response (HR), however, others can trigger HR in plant cells. Here, we reported the functional identification of two elicitors (partl₅248 and part2₄474) with signal peptide and LXAR motif from M. oryzae genome. Using agroinfection with a binary Potato virus X(PVX) vector, we showed that partl₅248 and part2₄474 genes can trigger cell death in Nicotiana benthamiana, but the cell death can be blocked by effectors which can inhibit hypersensitive cell death(HCD) by BAX. Meantime, the two genes could also trigger HR in Arabidopsis thaliana. Heterogenous expression of the two genes in yeast reduced the survival rate of yeast.