Analysis of plant and fungal gene expression during a functioning arbuscular mycorrhizal symbiosis

Arbuscular mycorrhizal fungi (AMF) (Order Glomales) form mutualistic symbioses with approximately 80% of terrestrial flowering plants. The beneficial effect of the AMF symbiosis on plant growth and development occurs as a result of a complex molecular dialogue between the two symbiotic partners. Identifying the molecules and genes involved in the dialogue is a prerequisite for a greater understanding of the symbiosis. Experimentally, differential RNA display by PCR was utilised to simultaneously compare the gene expression between a mycorrhizal and non-mycorrhizal root system during an established symbiotic state. Differentially expressed fragments were isolated, cloned and screened for authenticity. Full length mRNA transcripts have also been isolated and sequenced. One of the isolated cDNA’s corresponds to an AMF phosphoglycerate kinase (PGK) gene while a second corresponds to a ferrochelatase which is suppressed during mycorrhization. The PGK proteins shows high identity to those PGK’s of other fungi and the similarity to other isolated PGK’s will be illustrated. The results of these analyses, the importance and role in a functioning symbiosis of the PGK gene and the ferrochelatase gene transcript will be presented.
The authors are grateful to M. Shepherd for her technical assistance. This work was financially supported by SOAEFD.