A Cyst Nematode Effector Regulates Plant Gene Expressions Through Epigenetic Modifications
P. VIJAYAPALANI (1), T. Hewezi (2), M. Mitchum (3), T. Baum (1) (1) Iowa State University, U.S.A.; (2) University of Tennessee, U.S.A.; (3) University of Missouri, U.S.A.

Cyst nematodes secrete an array of effector proteins into host cells to manipulate host gene expressions and defense responses. A subset of effectors is actively imported into the host nucleus. The sugar beet cyst nematode Heterodera schachtii effector 32E03 is one such protein that targets the host nucleus. The effector 32E03 has no known homologs or functional domains. We determined that this effector physically interacts and co-localizes with Arabidopsis thaliana proteins AtHD and AtIMM, which have been shown to transcriptionally repress rDNA gene expression. In H. schachtii-infected A. thaliana, expression of both AtHD and AtIMM was significantly upregulated. In planta expression of 32E03 reduced total histone deacetylase activity, which lead to an enhanced acetylation at histone 3 lysine 9 along the ribosomal DNA (rDNA). As a consequence, there was a transcription derepression along the rDNA resulting in an enhanced bidirectional transcription along intergenic spacers. Consequently, there was an increased accumulation of processed siRNAs, leading to de novo methylation of DNA. These data demonstrate extensive modulation of plant gene expressions by a nematode effector through chromatin remodeling. 

Abstract Number: P9-318
Session Type: Poster