The Arabidopsis Thaliana AtPAE11 Encoding Pectin Acetyl Esteraseisinvolved In Nonhost Resistance To Phytophthora Sojae

Phytophthora sojae, a notorious oomycete pathogen of soybean, is a eukaryotic microorganism evolutionally distant from true fungi. Nonhost resistance is a common natural phenomenon, which is definedas resistance shown by an entire plant species to a specific parasite or pathogen. It is potentially wide-spectrum and durable.In this study, P. sojae and its nonhost Arabidopsis thaliana were employed to investigate the involvement of AtPAE11 in nonhost resistance. AtPAE11 encodes a pectin acetyl esterase which is predicted to be secreted protein. By creation of RNA silencing transformants, pathogenicity assays of additional T-DNA insertional mutants,and qRT-PCR assays, we aimed at understanding nonhost resistance in plants against oomycetes. Based on the confirmation of a susceptible mutant 1822 in the early stage of the laboratory, pathogenicity assays of additional T-DNA insertional A. thalianamutantsindicated that AtPAE11 mediates nonhost resistance to P. sojae. Genetic complementation assays with the AtPAE11 mutant 1822 showed recovered nonhost resistance to P. sojae through over-expression of AtPAE11.RNA silencing assays of AtPAE11 significantly reduced resistance to P. sojae, further confirming its role in mediating nonhost resistance.qRT-PCR assays showed thatAtMPK3( mitogen-activated protein kinase 3)was down-regulated in AtPAE11 mutant 1822 and RNA silencing-transformants.DAB staining showed that ROS burst is involved in AtPAE11-mediated nonhost resistance.Taken together, AtPAE11 is likely involved in the nonhost resistance in A. thaliana to the oomycete pathogen P. sojae, through AtMPK3-regulated ROS burst.