AUTHOR=Christakis Christos A. , Daskalogiannis Georgia , Chatzaki Anastasia , Markakis Emmanouil A. , Mermigka Glykeria , Sagia Angeliki , Rizzo Giulio Flavio , Catara Vittoria , Lagkouvardos Ilias , Studholme David J. , Sarris Panagiotis F. 

TITLE=Endophytic Bacterial Isolates From Halophytes Demonstrate Phytopathogen Biocontrol and Plant Growth Promotion Under High Salinity

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.681567

DOI=10.3389/fmicb.2021.681567

ISSN=1664-302X

ABSTRACT=<p>Halophytic endophytes potentially contribute to the host’s adaptation to adverse environments, improving its tolerance against various biotic and abiotic stresses. Here, we identified the culturable endophytic bacteria of three crop wild relative (CWR) halophytes: <italic>Cakile maritima</italic>, <italic>Matthiola tricuspidata</italic>, and <italic>Crithmum maritimum</italic>. In the present study, the potential of these isolates to improve crop adaptations to various stresses was investigated, using both <italic>in vitro</italic> and <italic>in-planta</italic> approaches. Endophytic isolates were identified by their 16S rRNA gene sequence and evaluated for their ability to: grow <italic>in vitro</italic> in high levels of NaCl; inhibit the growth of the economically important phytopathogens <italic>Verticillium dahliae</italic>, <italic>Ralstonia solanacearum</italic>, and <italic>Clavibacter michiganensis</italic> and the human pathogen <italic>Aspergillus fumigatus;</italic> provide salt tolerance <italic>in-planta</italic>; and provide growth promoting effect <italic>in-planta</italic>. Genomes of selected isolates were sequenced. In total, 115 endophytic isolates were identified. At least 16 isolates demonstrated growth under increased salinity, plant growth promotion and phytopathogen antagonistic activity. Three showed <italic>in-planta</italic> suppression of <italic>Verticillium</italic> growth. Furthermore, representatives of three novel species were identified: two <italic>Pseudomonas</italic> species and one <italic>Arthrobacter</italic>. This study provides proof-of-concept that the endophytes from CWR halophytes can be used as “bio-inoculants,” for the enhancement of growth and stress tolerance in crops, including the high-salinity stress.</p>