Ectopic expression of the mycorrhiza-specific chitinase gene Mtchit 3-3 in Medicago truncatula root-organ cultures stimulates spore germination of glomalean fungi

• Published in: The New phytologist 2005-08, Vol.167 (2), p.557-570
• Main Authors: Elfstrand, Malin, Feddermann, Nadja, Ineichen, Kurt, Nagaraj, Vinay Jantakahalli, Wiemken, Andres, Boller, Thomas, Salzer, Peter
• Format: Article
• Language: English
• Subjects: Agrobacterium; Agronomy. Soil science and plant productions; arbuscular mycorrhiza; Base Sequence; Biological and medical sciences; chitinase; Chitinases - genetics; class III chitinase (Mtchit 3‐3); Cloning, Molecular; complementary DNA; DNA, Fungal - genetics; Economic plant physiology; Fundamental and applied biological sciences. Psychology; Fungal spores; Fungi; Fusarium solani f. sp. phaseoli; Gene Expression; Genes, Fungal; Germination; Glomus; Glomus constrictum; Glomus intraradices; Hyphae; Inoculation; Medicago truncatula; Medicago truncatula - enzymology; Medicago truncatula - genetics; Medicago truncatula - microbiology; Microbial colonization; Molecular Sequence Data; mycorrhizae; Mycorrhizae - enzymology; Mycorrhizae - genetics; Mycorrhizae - physiology; mycorrhizal fungi; nucleotide sequences; organ culture; Parasitism and symbiosis; Phylogeny; Phytophthora megasperma; Phytophthora megasperma f.sp. medicaginis; plant pathogenic fungi; Plant physiology and development; plant proteins; Plant roots; Plant Roots - enzymology; Plant Roots - genetics; Plant Roots - microbiology; Plants; Plants, Genetically Modified; Polymerase chain reaction; promoter regions; Promoter Regions, Genetic; roots; root‐organ culture; Spore germination; Spores, Fungal; Symbiosis; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); transgenes; transgenic plants
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2005.01397.x

• Expression of Mtchit 3-3, a class III chitinase gene, is specifically induced by arbuscular mycorrhizal (AM) fungi in roots of the model legume Medicago truncatula and its transcripts accumulate in cells containing arbuscules. • Agrobacterium rhizogenes-transformed roots and root-organ cultures of M. truncatula were used to study effects of Mtchit 3-3 on AM fungi. • This work provides evidence for enzymatic activity of the Mtchit 3-3 gene product and shows with promoter:gus fusions that a 2 kb fragment located 5' upstream from the translational start codon of Mtchit 3-3 is sufficient to confer arbuscule-dependent gene expression. By fusing the Mtchit 3-3 coding region to the CaMV 35S promoter the expression pattern was disrupted. Surprisingly, disruption stimulated spore germination of Glomus intraradices and Glomus constrictum, and in the case of C. intraradices resulted in a higher probability of root colonization and spore formation. However, no effect on the abundance of arbuscules within colonized roots became apparent. • These observations demonstrate that disruption of the tight arbuscule-dependent expression pattern of Mtchit 3-3 has effects on the early interaction between roots and AM fungi.