Isolation of non-pathogenic Agrobacterium spp. biovar 1 from agricultural soils in Slovenia

The disease crown gall, which causes damage on perennial agricultural crops, is economically important in many countries. We therefore explored the presence of Agrobacterium spp. in a variety of agricultural soils where fruit trees are grown. Most samples were collected in four regions of Slovenia where a majority of fruit tree plantations are situated. Crown gall-affected plants were not observed on any of the sampling sites. Members of Agrobacterium spp. biovar 1 were isolated from 63 of the 72 soil samples (88%), but none from forest soil. All isolates of this Agrobacterium species complex were determined to be non-pathogenic by biotests and were assigned to genomic species based on a recA allele sequence analysis. Fourty-three isolates were allocated into genomic species G1 and 26 isolates into G4. Among both genomic species, new alleles of the recA gene were recognized: seven new alleles in G1 (denominated G1-15 to G1-21) and four in G4 (G4-7 to G4-10). Two alleles predominated among the Slovenian strains, recA-G1-15 and recA-G4-2. Different colony morphologies were observed between strains of G1 and G4 on KB medium

The Antibacterial Effect of Selected Essential Oils and Their Bioactive Constituents on <i>Pseudomonas savastanoi</i> pv. <i>savastanoi</i>: Phytotoxic Properties and Potential for Future Olive Disease Control

Plant pathogenic bacteria pose a significant threat to olive cultivation, leading to substantial economic losses and reduced yield. The efficacy of antimicrobial agents against these pathogens is of great interest for sustainable disease management strategies. As such, the management of olive knot disease is one of the major challenges in olive protection. In the presented study, through a series of in vitro assays, we investigated the antimicrobial effect of six essential oils (EOs) and their most concentrated constituents against causative agent of olive knot disease—Pseudomonas savastanoi pv. savastanoi, highlighting the high potential of Origanum compactum EO and its constituent carvacrol. Carvacrol exhibited the highest potential for practical application, demonstrating membrane disruption as its mechanism of action even at the lowest concentration. The bactericidal effect of antimicrobials was confirmed in a time–kill assay, where concentrations of MIC, 2× MIC, and 4× MIC were evaluated. Some of the applied treatments resulted in inhibition equal or higher than copper-based treatment. Additionally, we assessed the phytotoxicity of carvacrol by foliar application on olive cv. Leccino. The appearance of phytotoxic injuries majorly occurred on the young leaves of olive plants, with the highest proportion of damaged canopy observed when the 2× MIC concentration was applied. Due to its great efficiency against P. savastanoi pv. savastanoi in vitro, these findings highlight the potential of carvacrol as a molecule of interest for the development of environmentally friendly biopesticides. This study also contributes to the advancement of disease management practices in olive cultivation, leading to enhanced crop protection

Obvladovanje hruševega ožiga (Erwinia amylovora (Burrill) Winslow et al.)

Prvi pojav hruševega ožiga pri nas je uradno zabeležen leta 2001. Prvi večji izbruh bolezni v Sloveniji je bil v letu 2003, ko se je hrušev ožig razširil po celotni Gorenjski in v okolici Maribora. Ob drugem večjem izbruhu, ki se je zgodil leta 2007, se je bolezen razširila tudi proti jugu in vzhodu države. Hrušev ožig se je ustalil na Gorenjskem, Koroškem, na območju Maribora in na Notranjskem. Kasneje sta bili iz varovanega (neokuženega) območja izločeni še občini Lendava ter Renče-Vogrsko (južno od avtoceste H4)

Properties of bacterial cellulose produced using white and red grape bagasse as a nutrient source

The purpose of the study is to investigate the possibility of using wine industry wastes, such as red and white grape bagasse, to produce bacterial cellulose (BC) instead of using a costly commercial medium. BC was produced using grape bagasse as a carbon source replacement and the sole nutrient in the medium. The BC films were evaluated for their productivity and waterholding capacity. The BC films were also investigated for their morphology using scanning electron microscopy (SEM), their viscoelastic properties using dynamic mechanical analysis (DMA), and their chemical composition using Fourier-transform infrared spectroscopy (FTIR). Although the use of grape bagasse as the sole nutrient was successful in the preparation of BC, the BC films had inferior viscoelastic properties to other produced BC films. White grape bagasse proved to be an excellent carbon substitute as the production of BC and its water-holding capacity were five times higher and the produced BC films were up to 72% more flexible than the bacterial cellulose produced using standard HS medium

Primerjava diagnostičnih metod spremljanja pojava raka (Agrobacterium vitis Ophel & Kerr) žlahtne vinske trte (Vitis vinifera L.) v Sloveniji

Agrobacterium vitis causes common grape vine (Vitis vinifera L.) crown gall disease that destroyed a lot of Slovenian vineyards more than a decade ago. Eighty isolates of Agrobacterium spp. collected during monitoring in 2006 were identified as A. vitis and A. tumefacies by pehA and multiplex PCR method. Tumor-inducing capacity of these strains was assessed on test plants and with PCR methods for detection of the Ti plasmid responsible for tumor induction. With VCF3/VCR3 primer pair six false negatives and no false positives were detected. The high genetic diversity of pathogenic Agrobacterium spp. strains affects the performance of molecular methods, thus biological test should be performed where results from molecular methods are doubtful

Comparative study of diagnostic methods used for monitoring of common grape vine (Vitis vinifera L.) crown gall (Agrobacterium vitis Ophel & Kerr) in Slovenia

Agrobacterium vitis causes common grape vine (Vitis vinifera L.) crown gall disease that destroyed a lot of Slovenian vineyards more than a decade ago. Eighty isolates of Agrobacterium spp. collected during monitoring in 2006 were identified as A. vitis and A. tumefacies by pehA and multiplex PCR method. Tumor-inducing capacity of these strains was assessed on test plants and with PCR methods for detection of the Ti plasmid responsible for tumor induction. With VCF3/VCR3 primer pair six false negatives and no false positives were detected. The high genetic diversity of pathogenic Agrobacterium spp. strains affects the performance of molecular methods, thus biological test should be performed where results from molecular methods are doubtful