Transcriptional changes in response to arbuscular mycorrhiza development in the model plant Medicago truncatula.
Significant changes in root morphology and physiology during arbuscular mycorrhiza (AM) development are likely to be controlled by specific gene expression pattern in the host plant. Until now, little was known about transcriptional changes which occur AM-exclusively; that is, they do not occur during other root-microbe associations, nor are they induced by improved phosphate nutrition. In order to identify such AM-exclusive gene inductions of Medicago truncatula, we used a pool of different RNA samples as subtractor population in a suppressive subtractive hybridization (SSH) experiment. This approach resulted in the identification of a number of new AM-regulated genes. None of these genes were expressed in nonmycorrhiza roots or leaves. Electronic data obtained by comparison of the cDNA sequences to expressed sequence tag (EST) sequences from a wide range of cDNA libraries in the M. truncatula EST database (Gene Index, MtGI) support the mycorrhiza specificity of the corresponding genes, because sequences in the MtGI that were found to match the identified SSH-cDNA sequences originated exclusively from AM cDNA libraries. The promoter of one of those genes, MtGst1, showing similarities to plant glutathione-S-transferase (GST) encoding genes, was cloned and used in reporter gene studies. In contrast to studies with the potato GST gene PRP, MtGst 1 promoter activity was detected in all zones of the root cortex colonized by Glomus intraradices, but nowhere else.
Department of Molecular Genetics, University Hannover, Herrenhaeuser Str. 2, 30419 Hannover, Germany.
Anne
A
Wulf
Katja
K
Manthey
Jasmin
J
Doll
Andreas M
AM
Perlick
Burkhard
B
Linke
Thomas
T
Bekel
Folker
F
Meyer
Philipp
P
Franken
Helge
H
Küster
Franziska
F
Krajinski
D001483:Base Sequence; D017931:DNA Primers; D018506:Gene Expression Regulation, Plant; D029902:Medicago / Q000235:genetics* / Q000382:microbiology / Q000502:physiology; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000254:growth & development / Q000502:physiology*; D018517:Plant Roots / Q000502:physiology; D016133:Polymerase Chain Reaction; D018749:RNA, Plant / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013559:Symbiosis; D014158:Transcription, Genetic
D017931:DNA Primers; D018749:RNA, Plant