Interaction-dependent gene expression in Mla-specified response to barley powdery mildew.
Plant recognition of pathogen-derived molecules influences attack and counterattack strategies that affect the outcome of host-microbe interactions. To ascertain the global framework of host gene expression during biotrophic pathogen invasion, we analyzed in parallel the mRNA abundance of 22,792 host genes throughout 36 (genotype x pathogen x time) interactions between barley (Hordeum vulgare) and Blumeria graminis f. sp hordei (Bgh), the causal agent of powdery mildew disease. A split-split-plot design was used to investigate near-isogenic barley lines with introgressed Mla6, Mla13, and Mla1 coiled-coil, nucleotide binding site, Leu-rich repeat resistance alleles challenged with Bgh isolates 5874 (AvrMla6 and AvrMla1) and K1 (AvrMla13 and AvrMla1). A linear mixed model analysis was employed to identify genes with significant differential expression (P value < 0.0001) in incompatible and compatible barley-Bgh interactions across six time points after pathogen challenge. Twenty-two host genes, of which five were of unknown function, exhibited highly similar patterns of upregulation among all incompatible and compatible interactions up to 16 h after inoculation (hai), coinciding with germination of Bgh conidiospores and formation of appressoria. By contrast, significant divergent expression was observed from 16 to 32 hai, during membrane-to-membrane contact between fungal haustoria and host epidermal cells, with notable suppression of most transcripts identified as differentially expressed in compatible interactions. These findings provide a link between the recognition of general and specific pathogen-associated molecules in gene-for-gene specified resistance and support the hypothesis that host-specific resistance evolved from the recognition and prevention of the pathogen's suppression of plant basal defense.
Caldo
Rico A
RA
Department of Plant Pathology and Center for Plant Responses to Environmental Stresses, Iowa State University, Ames, Iowa 50011-1020, USA.
Nettleton
Dan
D
Wise
Roger P
RP
D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002450:Cell Communication / Q000235:genetics; D005658:Fungi / Q000472:pathogenicity*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D018745:Genome, Plant; D001467:Hordeum / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D006790:Host-Parasite Interactions / Q000235:genetics*; D007113:Immunity, Innate / Q000235:genetics*; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics; D019441:Plant Epidermis / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; C499582:Rar1 protein, Hordeum vulgare