Karakterizacija i biološka kontrola Xanthomonas campestris pv. campestris sa ozime uljane repice (Brassica napus l.)

Abstract

Bakterija Xanthomonas campestris pv. campestris je nedavno opisana kao patogen ozime uljane repice u Srbiji. Istraživanja u ovom radu su sprovedena na kolekciji od 65 izolata dobijenih sa različitih genotipova ozime uljane repice tokom 2014., 2016. i 2018. godine sa 10 lokaliteta u Vojvodini. Postojanje intraspecijskog genetičkog diverziteta populacije je utvrđeno korišćenjem rep-PCR i MLST/MLSA metodologije. Rezultati su ukazali na postojanje sedam genetički različitih grupa kod testiranih izolata i postojanje pet tipova sekvenci (ST3, ST5, ST9, ST26 i ST47) na osnovu kombinacije determinisanih alelskih profila, među kojima je ST47 najzastupljeniji. Svi proučavani izolati su bili patogeni na uljanoj repici i utvrđena je osetljivost kod svih 50 testiranih linija, sorti i hibrida uljane repice kao i kod 6 testiranih Brassica oleracea (kupus, kelj, keleraba, brokoli, raštan, karfiol) domaćina. Rezultati patogenosti su ukazali na postojanje tri grupe izolata, visoke, srednje i slabe virulentnosti. Metabarkoding analiza uticaja bakterije X. campestris pv. campestris na sastav autohtonih mikrobijalnih zajednica filosfere i rizosfere uljane repice pokazala je da je kod obolelih biljaka dolazilo do smanjenja bakterijskog diverziteta filosfere i zastupljenosti potencijalno korisnih bakterijskih rodova. Izolacijom tri biokontrolna agensa (Bacillus velezensis izolat X5-2, Bacillus megaterium izolat X6-3 i Pseudomonas orientalis izolat X2-1P) poreklom sa filosfere zdravih i zaraženih biljaka uljane repice sprovedena su istraživanja mogućnosti suzbijanja bakterije X. campestris pv. campestris u in vitro i in vivo uslovima. Takođe, u radu je dokazan genetički potencijal ovih izolata za produkciju lipopeptida i antibiotika, što je potvrđeno i hemijskom analizom njihovih ekstrakata

Xanthomonas campestris pv. campestris was described recently as a pathogen of winter oilseed rape in Serbia. This research was performed on a collection of 65 isolates obtained from different winter oilseed rape genotypes during 2014, 2016, and 2018 from 10 localities in Vojvodina. Intraspecies genetic diversity within the population was determined using rep-PCR and MLST/MLSA. Results indicated the existence of seven genetically distinct groups of tested isolates and five sequence types (ST3, ST5, ST9, ST26, and ST47) based on a combination of determined allelic profiles, with ST47 being the most common. All tested isolates were pathogenic on oilseed rape. All 50 tested lines, varieties, and hybrids of oilseed rape, as well as six tested Brassica oleracea (cabbage, kale, kohlrabi, broccoli, collard greens, cauliflower) hosts were susceptible to the tested isolates. The pathogenicity results indicated the existence of three groups of isolates showing high, medium, and low virulence. Metabarcoding analysis of the influence of the bacterium X. campestris pv. campestris on the composition of indigenous microbial communities of the oilseed rape phyllosphere and rhizosphere showed the reduction of bacterial diversity and abundance of potentially beneficial bacterial genera in the phyllosphere of diseased plants. By isolation of three biocontrol agents (Bacillus velezensis X5-2, Bacillus megaterium X6-3, and Pseudomonas orientalis X2-1P) from the phyllosphere of healthy and diseased oilseed rape plants, their possibility to control X. campestris pv. campestris was tested in vitro and in vivo. Within this work, the genetic potential of these isolates to produce lipopeptides and antibiotics was proven and confirmed by the chemical analysis of their extracts.