Submitted to: Federation of European Microbiological Societies Microbiology Letters
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/22/2003
Publication Date: 5/21/2003
Citation: DAVID-SCHWARTZ, R., GADKAR, V., NAGAHASHI, G., DOUDS, D.D., WININGER, S., KAPULNIK, Y. ROOT EXUDATE OF PMI TOMATO MUTANT M161 REDUCES AM FUNGAL PROLIFERATION IN VITRO. FEDERATION OF EUROPEAN MICROBIOLOGICAL SOCIETIES MICROBIOL LETTERS. v. 223. p. 193-198. 2003 Interpretive Summary: Arbuscular mycorrhizal [AM] fungi are naturally-occurring, beneficial soil fungi that colonize the roots of crop plants and increase their ability to take up nutrients from the soil. Some varieties of crop plants, which normally become colonized, do not and are called "mycorrhiza deficient mutants." These mutants block the colonization of roots by the fungus at different stages in the process. Studying these mutants helps us learn about those different stages. This research paper describes experiments in which we studied a mutant of tomato. We found that its roots released chemical compounds that inhibited the growth of AM fungi before they would reach the root. This was the first example of this type of mutant yet demonstrated and will help us understand the early stages of interaction between the root and fungus.
Technical Abstract: Soluble factors released from roots of the pre-mycorrhizal infection (pmi) Myc- tomato mutant M161 were analyzed. This mutant resists colonization by arbuscular mycorrhizal [AM] fungi. Aseptic whole exudates from the M161 mutant retarded the proliferation of Glomus intraradices in vitro. When the whole exudate was further fractionated on a C18 SEPAK cartridge, the 50/70% methanol fraction showed an activity against hyphal tip growth of Gigaspora gigantea and G. intraradices. Preliminary characterization of the exudate suggests that the inhibitory moietie(s) are heat labile, bind to PVPP (poly vinyl polypyrrolidone), and are not volatile. This is the first incidence of the inhibition mechanism of a Myc- plant being ascribed to inhibitory component(s) released in root exudate.