Transcript-based cloning of RRP46, a regulator of rRNA processing and R gene-independent cell death in barley-powdery mildew interactions.
Programmed cell death (PCD) plays a pivotal role in plant development and defense. To investigate the interaction between PCD and R gene-mediated defense, we used the 22K Barley1 GeneChip to compare and contrast time-course expression profiles of Blumeria graminis f. sp hordei (Bgh) challenged barley (Hordeum vulgare) cultivar C.I. 16151 (harboring the Mla6 powdery mildew resistance allele) and its fast neutron-derived Bgh-induced tip cell death1 mutant, bcd1. Mixed linear model analysis identified genes associated with the cell death phenotype as opposed to R gene-mediated resistance. One-hundred fifty genes were found at the threshold P value < 0.0001 and a false discovery rate <0.6%. Of these, 124 were constitutively overexpressed in the bcd1 mutant. Gene Ontology and rice (Oryza sativa) alignment-based annotation indicated that 68 of the 124 overexpressed genes encode ribosomal proteins. A deletion harboring six genes on chromosome 5H cosegregates with bcd1-specified cell death and is associated with misprocessing of rRNAs but segregates independent of R gene-mediated resistance. Barley stripe mosaic virus-induced gene silencing of one of the six deleted genes, RRP46 (rRNA-processing protein 46), phenocopied bcd1-mediated tip cell death. These findings suggest that RRP46, a critical component of the exosome core, mediates RNA processing and degradation involved in cell death initiation as a result of attempted penetration by Bgh during the barley-powdery mildew interaction but is independent of gene-for-gene resistance.
Department of Plant Pathology and Center for Plant Responses to Environmental Stresses, Iowa State University, Ames, Iowa 50011-1020, USA.
Liu
L
Xi
Matthew J
MJ
Moscou
Yan
Y
Meng
Weihui
W
Xu
Rico A
RA
Caldo
Miranda
M
Shaver
Dan
D
Nettleton
Roger P
RP
Wise
D001203:Ascomycota / Q000502:physiology*; D016923:Cell Death / Q000235:genetics / Q000502:physiology*; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D020459:Genes, rRNA / Q000235:genetics / Q000502:physiology*; D001467:Hordeum / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D010940:Plant Proteins; D012335:RNA, Ribosomal