Cloning and expression analysis of cDNAs corresponding to genes activated in cucumber showing systemic acquired resistance after BTH treatment.
BACKGROUND
Infection of plants by necrotizing pathogens can lead to the rapid and localized induction of a complex set of defense responses resulting in a restriction of pathogen growth and spread. Subsequently, an increase of plant resistance against a broad spectrum of pathogens is observed systemically. This plant immunity is known as Systemic Acquired Resistance. To identify components of the transduction pathway, we cloned and analysed the expression pattern of several mRNAs accumulating in cucumber plants after induction of Systemic Acquired Resistance.


RESULTS
We tested on cucumber different compounds known to induce systemic acquired resistance. Among these, BTH (benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester) proved to be very effective. mRNA RT-PCR differential display was used to identify mRNA sequences induced 24 hours after the application of 10 microM BTH to cucumber plants. A cDNA library constructed from cucumber plants sprayed with 10 microM BTH was screened to get corresponding full length cDNAs. Among the identified cDNAs were those coding for a putative ras-related GTP-binding protein, a putative beta-1,4-N-Acetylglucosaminyltranferase III and a putative pathogenesis related protein. The time course of accumulation of the three corresponding mRNAs was analysed by northern blotting in plants treated by BTH or in plants infected by Colletotrichum lagenarium.


CONCLUSIONS
The mRNA RT-PCR differential display technique allowed the identification of three genes possibly involved in Systemic Acquired Resistance in cucumber. Pathogenesis-related proteins are known to be involved in plant defence against pathogens. GTP-binding protein and N-acetylglucosaminyltranferase III have been reported to be components of signal transduction pathways in mammals and plants.
Bovie
Catherine
C
Laboratoire de Biologie Moléculaire et de Biotechnologie Végétales, Département des Sciences de la Vie, B22, Université de Liège, B-4000 Liège/Sart Tilman, Belgium. Catherine.Bovie@ulg.ac.be
Ongena
Marc
M
Thonart
Philippe
P
Dommes
Jacques
J
D015152:Blotting, Northern; D003001:Cloning, Molecular; D020231:Colletotrichum / Q000254:growth & development; D018553:Cucumis sativus / Q000187:drug effects / Q000235:genetics* / Q000382:microbiology; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000187:drug effects / Q000235:genetics; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics; D010454:Peptide Termination Factors / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013830:Thiadiazoles / Q000494:pharmacology*; D013997:Time Factors
D018076:DNA, Complementary; D010454:Peptide Termination Factors; D010940:Plant Proteins; D012333:RNA, Messenger; D013830:Thiadiazoles; C053376:pathogenesis-related proteins, plant; C041460:peptide chain termination release factor 2; C099403:S-methyl benzo(1,2,3)thiadiazole-7-carbothioate; D017351:N-Acetylglucosaminyltransferases; C054599:beta-1,4-mannosyl-glycoprotein beta-1,4-N-acetylglucosaminyltransferase; D020559:Monomeric GTP-Binding Proteins