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Research Project: Genetic Analysis of Complex Traits in Maize

Location: Plant Science Research

Title: Cytoplasmic and nuclear localizations are important for the hypersensitive response conferred by maize autoactive Rp1-D21 protein

item WANG, GUAN-FENG - North Carolina State University
item Balint-Kurti, Peter

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2015
Publication Date: 9/1/2015
Citation: Wang, G., Balint Kurti, P.J. 2015. Cytoplasmic and nuclear localizations are important for the hypersensitive response conferred by maize autoactive Rp1-D21 protein. Molecular Plant-Microbe Interactions. 28:1023-1031.

Interpretive Summary: In this paper we look at a protein that confers an autoactive defense (a kind of autoimmunity) response in maize (or corn). We show that the protein can be located both inside the nucleus of the cell and outside it in the cytoplasm. It turns out that the protein needs to be present in both the nucleus and the cytoplasm in order to confer the autoimmune phenotype. Furthermore our evidence strongly suggests that the protein has to move freely between these two compartments in order to function as expected.

Technical Abstract: Disease resistance (R-) genes have been isolated from many plant species. Most encode nucleotide binding leucine-rich-repeat (NLR) proteins that trigger a rapid localized programmed cell death termed the hypersensitive response (HR) upon pathogen recognition. Despite their structural similarities, different NLRs are distributed in a range of subcellular locations and analogous domains play diverse functional roles. The autoactive maize NLR gene Rp1-D21 derives from an intergenic recombination between two NLR genes, Rp1-D and Rp1-dp2 and confers an HR independent of the presence of a pathogen. Rp1-D21 and its N-terminal coiled coil (CC) domain (CCD21) confer autoactive HR when transiently expressed in Nicotiana benthamiana. Rp1-D21 was predominantly localized in cytoplasm with a small amount in the nucleus, while CCD21 was localized in both nucleus and cytoplasm. Targeting of Rp1-D21 or CCD21 exclusively to either the nucleus or the cytoplasm abolished HR-inducing activity. Co-expression of Rp1-D21 or CCD21 constructs confined, respectively, to the nucleus and cytoplasm, did not rescue full activity, suggesting nucleocytoplasmic movement was important for HR induction. Rp1-dp2 was localized in both soluble and plasma membrane fractions. The autoactive Rp1-dp2(D517V) mutant in the highly-conserved MHD motif abolished membrane localization, while the further introduction of the K225R P-loop mutation in Rp1-dp2(K225R/D517V) restored membrane distribution and abolished autoactivity. This work emphasizes the diverse structural and subcellular localization requirements for activity found among plant NLR R-genes.