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Title: Distinct domains of the AVRPM3A2/F2 avirulence protein from wheat powdery mildew are involved in immune receptor recognition and putative effector function

Author
item MCNALLY, KAITLIN - University Of Zurich
item MENARDO, FABRIZIO - University Of Zurich
item LUTHI, LINDA - University Of Zurich
item PRAZ, CORALINE - University Of Zurich
item MUELLER, MARION - University Of Zurich
item KUNZ, LUKAS - University Of Zurich
item BEN-DAVID, ROI - Volcani Center (ARO)
item CHANDRASEKHAR, KOTTAKOTA - Volcani Center (ARO)
item DINOOR, AMOS - Hebrew University Of Jerusalem
item Cowger, Christina
item MYERS, EMILY - North Carolina State University
item XUE, MINFENG - Hubei Academy Of Agricultural Sciences
item ZENG, FANSONG - Hubei Academy Of Agricultural Sciences
item GONG, SHUANGJUN - Hubei Academy Of Agricultural Sciences
item YU, DAZHAO - Hubei Academy Of Agricultural Sciences
item BOURRAS, SALIM - University Of Zurich
item KELLER, BEAT - University Of Zurich

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2018
Publication Date: 3/23/2018
Citation: McNally, K., Menardo, F., Luthi, L., Praz, C., Mueller, M., Kunz, L., Ben-David, R., Chandrasekhar, K., Dinoor, A., Cowger, C., Myers, E., Xue, M., Zeng, F., Gong, S., Yu, D., Bourras, S., Keller, B. 2018. Distinct domains of the AVRPM3A2/F2 avirulence protein from wheat powdery mildew are involved in immune receptor recognition and putative effector function. New Phytologist. 218:681-695.

Interpretive Summary: Recognition of the AVRPM3A2/F2 avirulence protein from powdery mildew by the wheat PM3A/F immune receptor induces a hypersensitive response after coexpression in Nicotiana benthamiana. The molecular determinants of this interaction and how they shape natural AvrPm3a2/f2 allelic diversity are unknown. We sequenced the AvrPm3a2/f2 gene in a worldwide collection of 272 mildew isolates. Using the natural polymorphisms of AvrPm3a2/f2 as well as sequence information from related gene family members, we tested 85 single-residue altered AVRPM3A2/F2 variants with PM3A, PM3F, and PM3FL456P/Y458H (modified for improved signaling) in Nicotiana benthamiana for effects on recognition. An intact AvrPm3a2/f2 gene was found in all analyzed isolates and the protein variant recognized by PM3A/F occurred globally at high frequencies. Single-residue alterations in AVRPM3A2/F2 mostly disrupted, but occasionally enhanced the recognition response by PM3A, PM3F and PM3FL456P/Y458H. Residues enhancing hypersensitive responses constituted a protein domain separate from both naturally occurring polymorphisms and positively selected residues of the gene family. These results demonstrate the utility of using gene family sequence diversity to screen residues for their role in recognition. This approach identified a putative interaction surface in AVRPM3A2/F2 not polymorphic in natural alleles. We conclude that molecular mechanisms besides recognition drive AvrPm3a2/f2 diversification.

Technical Abstract: Recognition of the AVRPM3A2/F2 avirulence protein from powdery mildew by the wheat PM3A/F immune receptor induces a hypersensitive response after coexpression in Nicotiana benthamiana. The molecular determinants of this interaction and how they shape natural AvrPm3a2/f2 allelic diversity is unknown. We sequenced the AvrPm3a2/f2 gene in a worldwide collection of 272 mildew isolates. Using the natural polymorphisms of AvrPm3a2/f2 as well as sequence information from related gene family members, we tested 85 single-residue altered AVRPM3A2/F2 variants with PM3A, PM3F, and PM3FL456P/Y458H (modified for improved signaling) in Nicotiana benthamiana for effects on recognition. An intact AvrPm3a2/f2 gene was found in all analyzed isolates and the protein variant recognized by PM3A/F occurred globally at high frequencies. Single-residue alterations in AVRPM3A2/F2 mostly disrupted, but occasionally enhanced the recognition response by PM3A, PM3F and PM3FL456P/Y458H. Residues enhancing hypersensitive responses constituted a protein domain separate from both naturally occurring polymorphisms and positively selected residues of the gene family. These results demonstrate the utility of using gene family sequence diversity to screen residues for their role in recognition. This approach identified a putative interaction surface in AVRPM3A2/F2 not polymorphic in natural alleles. We conclude that molecular mechanisms besides recognition drive AvrPm3a2/f2 diversification.