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The Magnaporthe oryzae Avirulence Gene AvrPiz-t Encodes a Predicted Secreted Protein That Triggers the Immunity in Rice Mediated by the Blast Resistance Gene Piz-t

2009; American Phytopathological Society; Volume: 22; Issue: 4 Linguagem: Inglês

10.1094/mpmi-22-4-0411

1943-7706

Wei Li, Baohua Wang, Jun Wu, Guodong Lu, Yajun Hu, Xing Zhang, Zhengguang Zhang, Qiang Zhao, Qi Feng, Hongyan Zhang, Zhengyi Wang, Guo‐Liang Wang, Bin Han, Zonghua Wang, Bo Zhou,

Plant Pathogens and Fungal Diseases

The Magnaporthe oryzae avirulence gene AvrPiz-t activates immunity in a gene-for-gene fashion to rice mediated by the blast resistance gene Piz-t. To dissect the molecular mechanism underlying their recognition, we initiated the cloning of AvrPiz-t using a map-based cloning strategy. The AvrPiz-t gene was delimited to an approximately 21-kb genomic fragment, in which six genes were predicted. Complementation tests of each of these six candidate genes led to the final identification of AvrPiz-t, which encodes a 108-amino-acid predicted secreted protein with unknown function and no homologues in M. oryzae or in other sequenced fungi. We found that AvrPiz-t is present in the virulent isolate GUY11 but contains a Pot3 insertion at a position 462 bp upstream from the start codon. Complementation tests of AvrPiz-t genes driven by promoters of varying length revealed that a promoter larger than 462 bp is essential to maintain the AvrPiz-t function. These results suggest that a Pot3 insertion in GUY11 might interfere with the proper function of AvrPiz-t. Additionally, we found that AvrPiz-t can suppress the programmed cell death triggered by mouse BAX protein in Nicotiana benthamiana, identifying a mechanism by which AvrPiz-t may contribute virulence of M. oryzae.