Characterisation of early transcriptional changes involving multiple signalling pathways in the Mla13 barley interaction with powdery mildew ( Blumeria graminis f. sp. hordei).
Suppression subtractive hybridisation was used to isolate 21 cDNAs ( bmi1- bmi21) up-regulated 1-5 h post-inoculation (hpi) in a barley ( Hordeum vulgare L. cv. Pallas) near-isogenic line (NIL) P11 ( Mla13) challenged with either avirulent or virulent isolates of Blumeria graminis f. sp. hordei. Transcriptional changes at these time-points are crucial for the Mla-mediated hypersensitive response [W.R. Bushnell and Z. Liu (1994) Physiol Mol Plant Pathol 44:389-402]. Seven sequences were up-regulated by 1 hpi, when the pathogen has formed only the primary germ tube. Some transcripts were similar to genes with a role in regulating programmed cell death in animals, including NF kappaB and oxysterol-binding protein. Moreover, bmi7, similar to rice resistance gene Xa21, was rapidly up-regulated in both compatible and incompatible interactions, but was then down-regulated by 5 hpi in the virulent interaction. Only nine of the transcripts were up-regulated in mlo5 resistance in cv. Pallas NIL P22, confirming differential pathway induction between Mla13 and mlo5. However, eight sequences up-regulated in the Mla13 response in P11 were already highly elevated in uninoculated mlo5 mutant P22, suggesting that they may be negatively regulated by wild-type Mlo. Regulation of bmi sequences was investigated using salicylic acid, methyl jasmonate, ethylene, H(2)O(2), abscisic acid, wounding and a glucan elicitor. No single stimulus up-regulated all genes, suggesting either combinations of these stimuli, or additional stimuli, are involved in early Mla13 and mlo5 resistances. Whereas H(2)O(2) up- or down-regulated 17 of the transcripts detected in Northern analyses, salicylic acid stimulated only down-regulation of 5 transcripts.
Hein
Ingo
I
Plant-Pathogen Interactions Programme, Scottish Crop Research Institute, Invergowrie, DD2 5DA, Dundee, UK.
Campbell
Edward I
EI
Woodhead
Mary
M
Hedley
Peter E
PE
Young
Vanessa
V
Morris
Wayne L
WL
Ramsay
Luke
L
Stockhaus
Joerg
J
Lyon
Gary D
GD
Newton
Adrian C
AC
Birch
Paul R J
PR
D000040:Abscisic Acid / Q000494:pharmacology; D000085:Acetates / Q000494:pharmacology; D017209:Apoptosis; D001203:Ascomycota / Q000254:growth & development*; D015152:Blotting, Northern; D003517:Cyclopentanes / Q000494:pharmacology; D018076:DNA, Complementary; D005030:Ethylenes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005936:Glucans / Q000494:pharmacology; D001467:Hordeum / Q000235:genetics* / Q000382:microbiology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007113:Immunity, Innate / Q000187:drug effects / Q000235:genetics; D054883:Oxylipins; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics*; D013314:Stress, Mechanical; D015533:Transcriptional Activation
D000085:Acetates; D003517:Cyclopentanes; D018076:DNA, Complementary; D005030:Ethylenes; D005936:Glucans; C104922:MLO protein, Hordeum vulgare; D054883:Oxylipins; D010940:Plant Proteins; D000040:Abscisic Acid; C072239:methyl jasmonate; C036216:ethylene; D006861:Hydrogen Peroxide; D020156:Salicylic Acid