The Medicago truncatula Vacuolar iron Transporter-Like proteins VTL4 and VTL8 deliver iron to symbiotic bacteria at different stages of the infection process.

Autor: Walton JH; Department of Biological Chemistry, John Innes Centre, Norwich, NR4 7UH, UK.; School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK., Kontra-Kováts G; Agricultural Biotechnology Institute, NARIC, Gödöllő, 2100, Hungary., Green RT; Department of Biological Chemistry, John Innes Centre, Norwich, NR4 7UH, UK., Domonkos Á; Agricultural Biotechnology Institute, NARIC, Gödöllő, 2100, Hungary., Horváth B; Agricultural Biotechnology Institute, NARIC, Gödöllő, 2100, Hungary., Brear EM; School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia., Franceschetti M; Department of Biological Chemistry, John Innes Centre, Norwich, NR4 7UH, UK., Kaló P; Agricultural Biotechnology Institute, NARIC, Gödöllő, 2100, Hungary.; Institute of Plant Biology, Biological Research Centre, Szeged, 6726, Hungary., Balk J; Department of Biological Chemistry, John Innes Centre, Norwich, NR4 7UH, UK.; School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK.
Jazyk: angličtina
Zdroj: The New phytologist [New Phytol] 2020 Oct; Vol. 228 (2), pp. 651-666. Date of Electronic Publication: 2020 Jul 16.
DOI: 10.1111/nph.16735
Abstrakt: The symbiotic relationship between legumes and rhizobium bacteria in root nodules has a high demand for iron, and questions remain regarding which transporters are involved. Here, we characterize two nodule-specific Vacuolar iron Transporter-Like (VTL) proteins in Medicago truncatula. Localization of fluorescent fusion proteins and mutant studies were carried out to correlate with existing RNA-seq data showing differential expression of VTL4 and VTL8 during early and late infection, respectively. The vtl4 insertion lines showed decreased nitrogen fixation capacity associated with more immature nodules and less elongated bacteroids. A mutant line lacking the tandemly-arranged VTL4-VTL8 genes, named 13U, was unable to develop functional nodules and failed to fix nitrogen, which was almost fully restored by expression of VTL8 alone. Using a newly developed lux reporter to monitor iron status of the bacteroids, a moderate decrease in luminescence signal was observed in vtl4 mutant nodules and a strong decrease in 13U nodules. Iron transport capability of VTL4 and VTL8 was shown by yeast complementation. These data indicate that VTL8, the closest homologue of SEN1 in Lotus japonicus, is the main route for delivering iron to symbiotic rhizobia. We propose that a failure in iron protein maturation leads to early senescence of the bacteroids.
(© 2020 The Authors. New Phytologist © 2020 New Phytologist Trust.)
Databáze: MEDLINE
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