Symbiosis-Related Plant Genes Modulate Molecular Responses in an Arbuscular Mycorrhizal Fungus During Early Root Interactions

• Published in: Molecular plant-microbe interactions Vol. 22; no. 3; pp. 341 - 351
• Main Authors: Seddas, Pascale M.A, Arias, Cecilia M, Arnould, Christine, Tuinen, Diederik van, Godfroy, Olivier, Benhassou, Hassan Ait, Gouzy, Jerome, Morandi, Dominique, Dessaint, Fabrice, Gianinazzi-Pearson, Vivienne
• Format: Journal Article
• Language: English
• Published: St. Paul, MN APS Press 01-03-2009; American Phytopathological Society; The American Phytopathological Society
• Subjects: Agronomy. Soil science and plant productions; appressoria; Biochemistry, Molecular Biology; Biological and medical sciences; cell wall components; Economic plant physiology; forage crops; forage legumes; Fundamental and applied biological sciences. Psychology; gene expression; Gene Expression Regulation, Plant - physiology; Genes, Plant; genome; Glomus intraradices; host plants; Life Sciences; Medicago truncatula; Medicago truncatula - metabolism; Medicago truncatula - microbiology; messenger RNA; microbial colonization; mutants; Mycorrhizae - metabolism; Phytopathology. Animal pests. Plant and forest protection; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Root Nodulation - physiology; Plant Roots - metabolism; Plant Roots - microbiology; root exudates; spore germination; symbionts; symbiosis; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); Symbiosis - physiology; transcription (genetics); vesicular arbuscular mycorrhizae; Symbiosis; Plant; Endomycorrhiza; Gene; Microbiology; Root; Mycorrhiza; Symbiont; ARBUSCULAR MYCORRHIZAL FUNGUS
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI-22-3-0341

To gain further insight into the role of the plant genome in arbuscular mycorrhiza (AM) establishment, we investigated whether symbiosis-related plant genes affect fungal gene expression in germinating spores and at the appressoria stage of root interactions. Glomus intraradices genes were identified in expressed sequence tag libraries of mycorrhizal Medicago truncatula roots by in silico expression analyses. Transcripts of a subset of genes, with predicted functions in transcription, protein synthesis, primary or secondary metabolism, or of unknown function, were monitored in spores and germinating spores and during interactions with roots of wild-type or mycorrhiza-defective (Myc-) mutants of M. truncatula. Not all the fungal genes were active in quiescent spores but all were expressed when G. intraradices spores germinated in wild-type M. truncatula root exudates or when appressoria or arbuscules were formed in association with wild-type M. truncatula roots. Most of the fungal genes were upregulated or induced at the stage of appressorium development. Inactivation of the M. truncatula genes DMI1, DMI2/MtSYM2, or DMI3/MtSYM13 was associated with altered fungal gene expression (nonactivation or inhibition), modified appressorium structure, and plant cell wall responses, providing first evidence that cell processes modified by symbiosis-related plant genes impact on root interactions by directly modulating AM fungal activity.