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

Abstract

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: Cakile maritima, Matthiola tricuspidata, and Crithmum maritimum. In the present study, the potential of these isolates to improve crop adaptations to various stresses was investigated, using both in vitro and in-planta approaches. Endophytic isolates were identified by their 16S rRNA gene sequence and evaluated for their ability to: grow in vitro in high levels of NaCl; inhibit the growth of the economically important phytopathogens Verticillium dahliae, Ralstonia solanacearum, and Clavibacter michiganensis and the human pathogen Aspergillus fumigatus; provide salt tolerance in-planta; and provide growth promoting effect in-planta. 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 in-planta suppression of Verticillium growth. Furthermore, representatives of three novel species were identified: two Pseudomonas species and one Arthrobacter. 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.

Bacterial Endophyte Community Dynamics in Apple (Malus domestica Borkh.) Germplasm and Their Evaluation for Scab Management Strategies

“…Liu et al, [41] reported that the endophyte community-shaping in apple is being determined by the type of tissue, the sampling site, and cultivar, which in turn have a prominent impact on the number of potential antifungal biota strains present. The plant endosymbiosiomes have been widely used to isolate microflora with biocontrol ability [42] and the studies on such entities have revealed their abilities to contribute in conferring resistance to crops against various phytopathogens, including other substantial benefits on the host such as nutrient acquisition, enhanced growth, and improved resistance to heat, drought, and other stresses [43]. The present study revealed that there is an abundant diversity of bacterial microflora across the Himalayan apple germplasm with respect to their antifungal behavior against V. inaequalis.…”

The Marine Endophytic Polyamine-Producing Streptomyces mutabilis UAE1 Isolated From Extreme Niches in the Arabian Gulf Promotes the Performance of Mangrove (Avicennia marina) Seedlings Under Greenhouse Conditions

“…Endophytes, microorganisms that naturally reside in tissues of living plants, are potential sources of novel natural products for exploitation in agriculture, industry, and medicine (Hallmann et al, 1997;El-Tarabily et al, 2009. Bacterial endophytes confer profound impacts on their host plants through promoting growth, increasing tolerance to pathogens, and improving phytoremediation (Ma et al, 2016;Christakis et al, 2021;Faria et al, 2021). In addition, they have the ability to produce a plethora of bioactive secondary metabolites to protect plants against environmental stresses (Khare et al, 2018;Kushwaha et al, 2020).…”

“…Direct mechanisms may enhance growth through fixation of nitrogen (N), solubilization of phosphorus (P), sequestration of iron (Fe), and production of plant growth regulators (PGRs), such as auxins, cytokinins (CKs), gibberellins (GA 3 ), ethylene (ET), and abscisic acid (ABA) (Olanrewaju et al, 2017;Gouda et al, 2018). Indirect growth promotion occurs when PGPB reduce the deleterious effects of pathogens on plant growth (Khare et al, 2018;Bektas and Kusek, 2021;Christakis et al, 2021).…”

Plant-Microbe Interaction in Sustainable Agriculture: The Factors That May Influence the Efficacy of PGPM Application

“…The Halophytic environment is also interesting to isolate useful microbes [261]. In an exhaustive study by Christakis et al [85], a total of 115 endophytic isolates were identified from three crop wild relative (CWR) halophytes: Cakile maritima, Matthiola tricuspidata, and Crithmum maritimum. From this selection, many strains showed antagonistic activity against the plant pathogens Verticillium dahliae, Ralstonia solanacearum, and Clavibacter michiganensis and the human pathogen Aspergillus fumigatus.…”