Defense genes are differentially induced by a mycorrhizal fungus and Rhizobium sp. in wild-type and symbiosis-defective pea genotypes

• Published in: Molecular plant-microbe interactions Vol. 12; no. 11; pp. 976 - 984
• Main Authors: Ruiz-Lozano, J.M, Roussel, H, Gianinazzi, S, Gianinazzi-Pearson, V
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01.11.1999; The American Phytopathological Society
• Subjects: Agronomy. Soil science and plant productions; appressoria; Biological and medical sciences; defense mechanisms; Economic plant physiology; Fundamental and applied biological sciences. Psychology; gene expression; genetic regulation; Genetics and breeding of economic plants; genotype; Glomus mosseae; inoculation; messenger RNA; mutants; nodulation; nodule symbioses; Pest resistance; Pisum sativum; Plant pathogens; Rhizobium leguminosarum; roots; symbiosis; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); Varietal selection. Specialized plant breeding, plant breeding aims; Aphanomyces euteiches; Plant pathogen; Phycomycetes; Glomus mosseae; Plant nodule; Induced resistance; Fungi; Gene; Dicotyledones; Angiospermae; Bacteria; Thallophyta; Symbiosis; Root; Vegetal microorganism relation; Gene expression; Rhizobium leguminosarum; Fungus resistance; Grain legume; Endomycorrhiza; Leguminosae; Pisum sativum; Mycorrhiza; Defense mechanism; Spermatophyta; Rhizobiaceae
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI.1999.12.11.976

Mycorrhiza-resistant and non-nodulating pea mutants provide a model system for identifying common genes regulated during the early events in mycorrhiza and nodule establishment. Inoculation of pea roots with Glomus mosseae or Rhizobium leguminosarum can induce overexpression of seven defense-related genes (pI 206, pI 49, pI 176, PR 10, basic A1-chitinase, transcinnamic acid 4-hydroxylase, chalcone isomerase), depending on the plant genotype and the time point of interaction between the plant and the microsymbiont. Expression of the pI 206 gene is closely correlated with appressorium formation by the mycorrhizal fungus on both mutant and wild-type pea roots. The gene is also induced by the pathogen Aphanomyces euteiches. Transcript accumulation was higher in mutant than in wild-type genotypes for five and six of the studied genes during early stages of root interactions with G. mosseae and R. leguminosarum, respectively, and this is discussed in relation to the symbiotic-defective phenotype of Myc-1Nod- pea. The early induction of similar plant defense genes in response to arbuscular mycorrhizal fungi and rhizobia reinforces the hypothesis of common regulatory steps in both root symbioses.