ANNEXIN 8 negatively regulates RPW8.1-mediated cell death and disease resistance in Arabidopsis.


Zhao ZX(1), Xu YJ(1), Lei Y(1), Li Q(1), Zhao JQ(1), Li Y(1), Fan J(1), Xiao S(2), Wang WM(1).
Author information:
(1)Rice Research Institute and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China.
(2)Institute for Bioscience and Biotechnology Research & Department of Plant Science and Landscape Architecture, University of Maryland, Rockville, Maryland, 20850, USA.


Study on the regulation of broad-spectrum resistance is an active area in plant biology. RESISTANCE TO POWDERY MILDEW 8.1 (RPW8.1) is one of a few broad-spectrum resistance genes triggering the hypersensitive response (HR) to restrict multiple pathogenic infections. To address the question how RPW8.1 signaling is regulated, we performed a genetic screen and tried to identify mutations enhancing RPW8.1-mediated HR. Here, we provided evidence to connect an annexin protein with RPW8.1-mediated resistance in Arabidopsis against powdery mildew. We isolated and characterized Arabidopsis b7-6 mutant. A point mutation in b7-6 at the At5g12380 locus resulted in an amino acid substitution in ANNEXIN 8 (AtANN8). Loss-of-function or RNA-silencing of AtANN8 led to enhanced expression of RPW8.1, RPW8.1-dependent necrotic lesions in leaves, and defense against powdery mildew. Conversely, over-expression of AtANN8 compromised RPW8.1-mediated disease resistance and cell death. Interestingly, the mutation in AtANN8 enhanced RPW8.1-triggered H2 O2 . In addition, mutation in AtANN8 led to hypersensitivity to salt stress. Together, our data indicate that AtANN8 is involved in multiple stress signaling pathways and negatively regulates RPW8.1-mediated resistance against powdery mildew and cell death, thus linking ANNEXIN's function with plant immunity.