HPR1, a component of the THO/TREX complex, plays an important role in disease resistance and senescence in Arabidopsis.

ENHANCED DISEASE RESISTANCE 1 (EDR1) is a negative regulator of powdery mildew resistance, cell death and ethylene-induced senescence. To identify components involved in EDR1 signaling, we performed a forward genetic screen for edr1 suppressors. In this screen, we identified the hpr1-4 mutation, which partially suppresses edr1-mediated resistance to the powdery mildew pathogen Golovinomyces cichoracearum and mildew-induced cell death. However, the hpr1-4 mutation enhanced the ethylene-induced senescence phenotype of edr1. The hpr1-4 single mutant displayed enhanced susceptibility to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 and the oomycete pathogen Hyaloperonospora arabidopsidis Noco2. Arabidopsis HPR1 encodes a homolog of human HPR1, a component of the conserved THO/transcription export (THO/TREX) complex that is required for mRNA export in yeast and humans. HPR1 is expressed in various organs and throughout all developmental stages. HPR1 localizes to the nucleus, and, significantly, mRNA export is compromised in the hpr1-4 mutant. Taken together, these data demonstrate that HPR1 plays an important role in disease resistance in plants, and that the THO/TREX complex is functionally conserved among plants, yeast and humans. Our data indicate a general link between mRNA export, defense responses and ethylene signaling in plants.

Pan H ，Liu S ，Tang D 《-》

The THO/TREX complex functions in disease resistance in Arabidopsis.

Pan H ，Liu S ，Tang D 《-》

Suppression of edr2-mediated powdery mildew resistance, cell death and ethylene-induced senescence by mutations in ALD1 in Arabidopsis.

EDR2 is a negative regulator of the defense response and cell death in Arabidopsis. Loss-of-function of EDR2 leads to enhanced resistance to powdery mildew. To identify new components in the EDR2 signal transduction pathway, mutations that suppress edr2 resistant phenotypes were screened. Three mutants, edts5-1, edts5-2 and edts5-3 (edrtwo suppressor 5), were identified. The EDTS5 gene was identified by map-based cloning and previously was shown to encode an aminotransferase (ALD1). Therefore we renamed these three alleles ald1-10, ald1-11 and ald1-12, respectively. Mutations in ALD1 suppressed all edr2-mediated phenotypes, including powdery mildew resistance, programmed cell death and ethylene-induced senescence. Accumulation of hydrogen peroxide in edr2 was also suppressed by ald1 mutation. The expression of defense-related genes was up-regulated in the edr2 mutant, and the up-regulation of those genes in edr2 was suppressed in the edr2/ald1 double mutant. The ald1 single mutant displayed delayed ethylene-induced senescence. In addition, ald1 mutation suppressed edr1-mediated powdery mildew resistance, but could not suppress the edr1/edr2 double-mutant phenotype. These data demonstrate that ALD1 plays important roles in edr2-mediated defense responses, and senescence and revealed a crosstalk between ethylene and salicylic acid signaling mediated by ALD1 and EDR2.

Nie H ，Wu Y ，Yao C ，Tang D ... -  《Journal of Genetics and Genomics》

HYPER RECOMBINATION1 of the THO/TREX complex plays a role in controlling transcription of the REVERSION-TO-ETHYLENE SENSITIVITY1 gene in Arabidopsis.

Xu C ，Zhou X ，Wen CK 《-》

Characterization of a novel, defense-related Arabidopsis mutant, cir1, isolated by luciferase imaging.

Murray SL ，Thomson C ，Chini A ，Read ND ，Loake GJ ... -  《MOLECULAR PLANT-MICROBE INTERACTIONS》