Isolation and Characterization of Putative Endophytic Bacteria Antagonistic to Phoma tracheiphila and Verticillium albo-atrum

Abstract

A collection of 200 bacterial isolates recovered from citrus plants (Citrus limon, Citrus sinensis, and Citrus reticulata), Medicago truncatula and Laurus nobilis, was established. In vitro screening indicated that 28 isolates exhibited an inhibitory activity against the vascular pathogens Phoma tracheiphila and Verticillium albo-atrum. Isolates were screened according to their hydrolytic activities, plant growth-promoting bacteria (PGPB) abilities, as well as for the presence of nonribosomal peptide synthetase (NRPS) genes responsible of the lipopeptide biosynthesis. The results were positive for 16 isolates which exhibited at least two PGPB activities and a single NRPS gene. Genetic diversity of the selected isolates was studied using random amplified polymorphic DNA (RAPD) and repetitive element PCR (REP) tools that showed clustering of strains into three major groups (I, II, and III) (i, ii, and iii), respectively. Clustering was further confirmed by the 16S rDNA sequencing that assigned nine isolates to Bacillus velezensis, four isolates to Bacillus methyltrophicus, one isolate to Bacillus amyloliquefaciens, and two isolates to Bacillus mojavensis. Organ-bacterial genotype interaction as well as positive correlation with NRPS genes are discussed.

Biocontrol of Fusarium Wilt and Growth Promotion of Tomato Plants Using Endophytic Bacteria Isolated from Solanum elaeagnifolium Stems

“…This is in agreement partly with Kalai‐Grami et al. () findings where endophytic Bacillus spp. ( B. velezensis , B. mojavensis , B .…”

Endophytic Bacteria from Datura stramonium for Fusarium Wilt Suppression and Tomato Growth Promotion

“…S40. Similar findings were reported for endophytic several B. velezensis, B. mojavensis, and B. methylotrophicus strains [6] but B. subtilis subsp. subtilis str.…”

“…In fact, as reported in previous studies, endophytic bacteria may exhibit antifungal potential directly toward fungal pathogens and may act indirectly through the promotion of plant growth [45]. Similar growth enhancements were also achieved using B. mojavensis for treatment of maize plants grown in presence of F. verticillioides pathogenic isolates [6]. PGPB potential was also investigated by using endophytic B. amyloliquefaciens, isolated from soybean roots, leading to enhanced soybean yield [46].…”

“…Endophytic Bacillus spp. (B. mojavensis, B. subtilis, B. pumilis, B. amyloliquefaciens) are commonly known as lipopeptide antibiotics [59] and/or hydrolytic enzymes producing strains [6]. Furthermore, the production of HCN is involved in the effective inhibition of pathogen.…”

“…Given the endogenous progress of the pathogen within plant tissues, the use of endophytic microorganisms (fungi or bacteria) could better limit the disease [6,7].…”