The present study was conducted to assess the antifungal activity of essential oils of medicinal plants Mentha piperita (peppermint), Foeniculum vulgare, Satureja hortensis (Savory), Ferula asafoetida and Cuminum cyminum against Alternaria sp., Bipolaris sorokiniana and Acremonium sclerotigenum. The antifungal activity was evaluated by Broth Microdilution Method. Minimum Inhibitory Concentration (MICs) and Minimum Fungicidal Concentration (MFCs) of the essential oils were compared with Amphotricin B and Captan as standard drug. MIC values for all essential oils were between 1 to 8 mg/mL. MIC value of Fennel essential oil was comparable to MFC value obtained from fungicide Captan. Peppermint essential oil exhibited maximum inhibitory and fungicide activity in concentrations of 2 mg/ml and 4 mg/ml against Alternaria sp. The essential oil was more effective than Fennel against Bipolaris, but MFC values of both essential oils were 4 mg/ml. C. cyminum displayed less susceptibility against all of the fungi. Regarding our finding, peppermint and Fennel oil seem to be a promising solution to control plant diseases.

In this study, we explored the pathogenicity and phylogenetic position of Agrobacterium spp. strains isolated from crown gall tissues on annual, perennial, and ornamental plants in Iran. Of the 43 strains studied, 10 strains were identified as Allorhizobium vitis (formerly Agrobacterium vitis) using the species-specific primer pair PGF/PGR. Thirty-three remaining strains were studied using multilocus sequence analysis of four housekeeping genes (i.e., atpD, gyrB, recA, and rpoB), from which seven strains were identified as A. larrymoorei and one strain was identified as A. rubi (Rer); the remaining 25 strains were scattered within the A. tumefaciens species complex. Two strains were identified as genomospecies 1 (G1), seven strains were identified as A. radiobacter (G4), seven strains were identified as A. deltaense (G7), two strains were identified as A. nepotum (G14), and one strain was identified as “A. viscosum” (G15). The strains Rnr, Rnw, and Rew as well as the two strains OT33 and R13 all isolated from rose and the strain Ap1 isolated from apple were clustered in three atypical clades within the A. tumefaciens species complex. All but eight strains (i.e., Nec10, Ph38, Ph49, fic9, Fic72, R13, OT33, and Ap1) were pathogenic on tomato and sunflower seedlings in greenhouse conditions, whereas all but three strains (i.e., fic9, Fic72, and OT33) showed tumorigenicity on carrot root discs. The phylogenetic analysis and nucleotide diversity statistics suggested the existence of two novel genomospecies within the A. tumefaciens species complex, which we named “G19” and “G20.” Hence, we propose the strains Rew, Rnw, and Rnr as the members of “G19” and the strains R13 and OT33 as the members of G20, whereas the phylogenetic status of the atypical strain Ap1 remains undetermined.

The genus Xanthomonas contains a set of diverse bacterial strains, most of which are known for their pathogenicity on annual crops and fruit trees causing economically important plant diseases. Recently, five Xanthomonas strains were isolated from Agrobacterium -induced crown gall tissues of amaranth (Amaranthus sp.) and weeping fig (Ficus benjamina) plants in Iran. Phenotypic characteristics (i.e. biochemical tests and pathogenicity features) and whole genome sequence-based core-genome phylogeny followed by average nucleotide identity and digital DNA–DNA hybridization calculations suggested that these gall-associated strains belong to two new species within the genus Xanthomonas . In this study, we provide a formal species description for these new species where Xanthomonas bonasiae sp. nov. is proposed for the strains isolated from weeping fig with FX4T (=CFBP 8703T=DSM 112530T) as type strain. The name Xanthomonas youngii sp. nov. is proposed for the strains isolated from amaranth with AmX2T (=CFBP 8902T=DSM 112529T) as type strain.

Tumorigenic agrobacteria—members of the bacterial family Rhizobiaceae —cause crown gall and hairy root diseases on a broad range of plant species. These bacteria are responsible for economic losses in nurseries of important fruit trees and ornamental plants.