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Genomic insights into plant-growth-promoting potentialities of the genus Frankia

Lookup NU author(s): Dr Imen Nouioui, Carlos Cortes, Emeritus Professor Hans-Peter Klenk, Professor Michael Goodfellow



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Copyright © 2019 Nouioui, Cortés-albayay, Carro, Castro, Gtari, Ghodhbane-Gtari, Klenk, Tisa, Sangal and Goodfellow. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.This study was designed to determine the plant growth promoting (PGP) potential of members of the genus Frankia. To this end, the genomes of 21 representative strains were examined for genes associated directly or indirectly with plant growth. All of the Frankia genomes contained genes that encoded for products associated with the biosynthesis of auxins [indole-3-glycerol phosphate synthases, anthranilate phosphoribosyltransferases (trpD), anthranilate synthases, and aminases (trpA and B)], cytokinins (11 well-conserved genes within the predicted biosynthetic gene cluster), siderophores, and nitrogenases (nif operon except for atypical Frankia) as well as genes that modulate the effects of biotic and abiotic environmental stress (e.g., alkyl hydroperoxide reductases, aquaporin Z, heat shock proteins). In contrast, other genes were associated with strains assigned to one or more of four host-specific clusters. The genes encoding for phosphate solubilization (e.g., low-affinity inorganic phosphate transporters) and lytic enzymes (e.g., cellulases) were found in Frankia cluster 1 genomes, while other genes were found only in cluster 3 genomes (e.g., alkaline phosphatases, extracellular endoglucanases, pectate lyases) or cluster 4 and subcluster 1c genomes (e.g., NAD(P) transhydrogenase genes). Genes encoding for chitinases were found only in the genomes of the type strains of Frankia casuarinae, F. inefficax, F. irregularis, and F. saprophytica. In short, these in silico genome analyses provide an insight into the PGP abilities of Frankia strains of known taxonomic provenance. This is the first study designed to establish the underlying genetic basis of cytokinin production in Frankia strains. Also, the discovery of additional genes in the biosynthetic gene cluster involved in cytokinin production opens up the prospect that Frankia may have novel molecular mechanisms for cytokinin biosynthesis.

Publication metadata

Author(s): Nouioui I, Cortes-Albayay C, Carro L, Castro JF, Gtari M, Ghodhbane-Gtari F, Klenk H-P, Tisa LS, Sangal V, Goodfellow M

Publication type: Article

Publication status: Published

Journal: Frontiers in Microbiology

Year: 2019

Volume: 10

Online publication date: 04/07/2019

Acceptance date: 11/06/2019

Date deposited: 05/08/2019

ISSN (electronic): 1664-302X

Publisher: Frontiers Media S.A.


DOI: 10.3389/fmicb.2019.01457


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