Disease relevance of RPP8

• RCY1, an Arabidopsis thaliana RPP8/HRT family resistance gene, conferring resistance to cucumber mosaic virus requires salicylic acid, ethylene and a novel signal transduction mechanism [1].

High impact information on RPP8

• Hence, the HRT/RPP8 family provides molecular evidence that sequence changes between closely related members of multigene families can generate novel specificities for radically different pathogens [2].
• HRT is a member of the class of resistance (R) genes that contain a leucine zipper, a nucleotide binding site, and leucine-rich repeats [2].
• Turnip crinkle virus (TCV) inoculation onto TCV-resistant Arabidopsis leads to a hypersensitive response (HR) controlled by the dominant gene HRT [2].
• The RPP8 haplotype in Ler-0 contains the functional RPP8-Ler gene and a nonfunctional homolog, RPH8A [3].
• Smaller blocks of synteny were identified between soyA2 and Arabidopsis chromosomes IV and V (near the RPP5 and RPP8 genes) and between soyA2 and Arabidopsis chromosomes I and V (near the PhyA and PhyC genes) [4].

Biological context of RPP8

• A similar SA dependence was observed for the P. parasitica TIR and CC-class R genes RPP5 and RPP8, respectively [5].
• To understand these changes, we generated a whole genome transcript profile for RCY1-mediated resistance to cucumber mosaic virus strain Y (CMV-Y) in Arabidopsis [6].
• We propose that antagonistic interactions between the SA and JA signaling mechanisms modulate defense gene expression and the activation of RCY1-conferred gene-for-gene resistance to CMV(Y) [7].
• The RCY1 locus was mapped between two CAPS markers, DFR and T43968, which were located in the region containing genetically defined disease resistance genes and their homologues [8].

Anatomical context of RPP8

• We also demonstrate that a variety of resistance-associated phenomena, including the TCV-induced accumulation of salicylic acid, camalexin and autofluorescent cell-wall material, correlate with the HR, suggesting the possibility that HRT is required for their activation [9].

Associations of RPP8 with chemical compounds

• However, the absence of light did not affect either TCV-induced elevated levels of free SA or the expression of HRT [10].

Other interactions of RPP8

• High levels of SA upregulate HRT expression via a PAD4-dependent pathway [11].
• Here, we demonstrate that unlike most CC-NBS-LRR R genes, HRT/rrt-mediated resistance is dependent on EDS1 and independent of NDR1 [11].

References