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Turgeman T, Lubinsky O, Roth-Bejerano N, Kagan-Zur V, Kapulnik Y, Koltai H, Zaady E, Ben-Shabat S, Guy O, Lewinsohn E, Sitrit Y. The role of pre-symbiotic auxin signaling in ectendomycorrhiza formation between the desert truffle Terfezia boudieri and Helianthemum sessiliflorum. Mycorrhiza 2016; 26:287-297. [PMID: 26563200 DOI: 10.1007/s00572-015-0667-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 10/26/2015] [Indexed: 06/05/2023]
Abstract
The ectendomycorrhizal fungus Terfezia boudieri is known to secrete auxin. While some of the effects of fungal auxin on the plant root system have been described, a comprehensive understanding is still lacking. A dual culture system to study pre mycorrhizal signal exchange revealed previously unrecognized root-fungus interaction mediated by the fungal auxin. The secreted fungal auxin induced negative taproot gravitropism, attenuated taproot growth rate, and inhibited initial host development. Auxin also induced expression of Arabidopsis carriers AUX1 and PIN1, both of which are involved in the gravitropic response. Exogenous application of auxin led to a root phenotype, which fully mimicked that induced by ectomycorrhizal fungi. Co-cultivation of Arabidopsis auxin receptor mutants tir1-1, tir1-1 afb2-3, tir1-1 afb1-3 afb2-3, and tir1-1 afb2-3 afb3-4 with Terfezia confirmed that auxin induces the observed root phenotype. The finding that auxin both induces taproot deviation from the gravity axis and coordinates growth rate is new. We propose a model in which the fungal auxin induces horizontal root development, as well as the coordination of growth rates between partners, along with the known auxin effect on lateral root induction that increases the availability of accessible sites for colonization at the soil plane of fungal spore abundance. Thus, the newly observed responses described here of the root to Terfezia contribute to a successful encounter between symbionts.
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Affiliation(s)
- Tidhar Turgeman
- The Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel
| | - Olga Lubinsky
- Life Sciences Department, Ben-Gurion University of the Negev, 84105, Beer-Sheva, Israel
| | - Nurit Roth-Bejerano
- Life Sciences Department, Ben-Gurion University of the Negev, 84105, Beer-Sheva, Israel
| | - Varda Kagan-Zur
- Life Sciences Department, Ben-Gurion University of the Negev, 84105, Beer-Sheva, Israel
| | - Yoram Kapulnik
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Bet-Dagan, 50250, Israel
| | - Hinanit Koltai
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Bet-Dagan, 50250, Israel
| | - Eli Zaady
- Agricultural Research Organization, Gilat Research Center, 85280, Beer-Sheva, Israel
| | - Shimon Ben-Shabat
- Department of Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105, Beer-Sheva, Israel
| | - Ofer Guy
- Desert Agro-Research Center, Ramat-Negev R & D, D.N, 85515, Halutza, Israel
| | - Efraim Lewinsohn
- Department of Vegetable Crops, Newe Yaár Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay, Israel
| | - Yaron Sitrit
- The Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel.
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