Identification of a cDNA from the arbuscular mycorrhizal fungus Glomus intraradices that is expressed during mycorrhizal symbiosis and up-regulated by N fertilization.
A cDNA library was constructed with RNA from Glomus intraradices-colonized lettuce roots and used for differential screening. This allowed the identification of a cDNA (Gi-1) that was expressed only in mycorrhizal roots and was of fungal origin. The function of the gene product is unknown, because Gi-1 contained a complete open reading frame that was predicted to encode a protein of 157 amino acids which only showed little homology with glutamine synthetase from Helicobacter pylori. The time-course analysis of gene expression during the fungal life cycle showed that Gi-1 was expressed only during the mycorrhizal symbiosis and was not detected in dormant or germinating spores of G. intraradices. P fertilization did not significantly change the pattern of Gi-1 expression compared with that in the unfertilized treatment, whereas N fertilization (alone or in combination with P) considerably enhanced the Gi-1 transcript accumulation. This increase in gene expression correlated with plant N status and growth under such conditions. The possible role of the Gi-1 gene product in intermediary N metabolism of arbuscular mycorrhizal symbiosis is further discussed.
Ruiz-Lozano
Juan M
JM
Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (CSIC), Granada, Spain. juanmanuel.ruiz@eez.csis.es
Collados
Carlos
C
Porcel
Rosa
R
Azcón
Rosario
R
Barea
José M
JM
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D020369:Bradyrhizobium / Q000187:drug effects / Q000254:growth & development; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005308:Fertilizers; D005658:Fungi / Q000235:genetics* / Q000254:growth & development; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000494:pharmacology; D010758:Phosphorus / Q000494:pharmacology; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013025:Glycine max / Q000235:genetics / Q000382:microbiology; D013559:Symbiosis; D015854:Up-Regulation / Q000187:drug effects; D014867:Water / Q000494:pharmacology / Q000502:physiology
D018076:DNA, Complementary; D005308:Fertilizers; D014867:Water; D010758:Phosphorus; D009584:Nitrogen