Biološka kontrola skladišnih fitopatogenih gljiva

The intensive use of fungicides has resulted in accumulation of toxic compounds potentially hazardous to humans and environment, and also in the build up of resistance of the pathogens. The development and application of biological agents is one of the alternative measures. Screening is a critical step in the development of biological control agents. The success of all subsequent stages depends on the ability of a screening procedure to identify an appropriate candidat. In the last two decades a large number of studies have shown that antagonistic migroorganisms from the genus Trichoderma, Gliocladium, Bacillus and Streptomyces able to reduce the activity of postharvest fungal pathogens.Intenzivna primena fungicida dovela je do nagomilavanja toksičnih jedinjenja, potencijalno opasnih po zdravlje ljudi i životnu sredinu, i razvoja rezistentnosti patogena. Razvoj i primena bioloških agenasa je jedna od alternativnih mera. Skrining je kritičan korak u razvoju bioloških agenasa. Uspeh u svim kasnijim fazama zavisi od postupka skrininga i identifikacije odgovarajućeg antagoniste. U toku poslednje dve decenije mnogobrojna istraživanja su pokazala da biološki agensi iz roda Trichoderma, Gliocladium, Bacillus i Streptomyces imaju sposobnost redukcije skladišnih fitopatogenih gljiva

Erwinia amylovora – prouzrokovač nekroze korenovog vrata stabla jabuke

A large-scale outbreak of fire blight symptoms caused by Erwinia amylovora was recorded in pome fruit trees during 2007. In addition to fruit necrosis and shoot blight as the typical disease symptoms, dark purple necrosis was observed in the root collar area girdling the trunk just above the ground and thus withering the whole apple tree. Since similar symptoms on apple trees could be caused by E. amylovora or one of several phytopathogenic fungi of the genera Phomopsis and Phytophthora, an investigation was conducted to identify the causal agent of this disease. Levan-producing, nonfluorescent bacteria were isolated from diseased samples. The isolated strains produced HR in tobacco leaves and necrosis of artificially inoculated, immature pear fruits, followed by oozing of bacterial exudate, a characterisitic of E. amylovora. Based on the results of pathogenicity tests, biochemical characteristics, ELISA test and PCR analysis, it was confirmed that the investigated strains belonged to E. amylovora, causing the root collar necrosis of apple trees as an atypical symptom of this bacterium in Serbia. The explanation of this symptom may be that the vegetative rootstocks were infected with E. amylovora. Therefore, the development of diagnostic protocols for detection of E. amylovora in apple rootstock is very important for health inspections of planting materials.Tokom 2007. godine zabeležena je masovna pojava bakteriozne plamenjače jabučastih voćaka prouzrokovana bakterijom Erwinia amylovora. Pored nekroze plodova i plamenjače mladara, tipičnih simptoma bolesti, našu pažnju je privukla pojava nekroze mrkoljubičaste boje u zoni korenovog vrata, koja prstenasto zahvata prizemni deo i prouzrokuje izumiranje stabala jabuke. S obzirom na to da uzrok ovakvih patoloških promena može da bude E. amylovora, ali i fitopatogene gljive iz rodova Phomopsis i Phytophthora, preduzeta su istraživanja sa ciljem da se utvrdi etiologija ovog oboljenja jabuke. Iz obolelih uzoraka izolovane su bakterije koje stvaraju levan, ali ne i fluorescentni pigment. Proučavani sojevi prouzrokovali su HR na listovima duvana i nekrozu inokulisanih, nesazrelih plodova kruške, uz obilno stvaranje bakterijskog eksudata, što je karakterističan znak E. amylovora. Na osnovu rezultata dobijenih pri testovima provere patogenosti, ali i rezultata biohemijskih odlika, ELISA testa i molekularnih metoda (PCR), potvrđeno je da proučavani izolati pripadaju bakteriji E. amylovora, koja je uzročnik simptoma nekroze korenovog vrata stabala jabuke, prvi put zabeleženih u Srbiji. Moguće objašnjenje ove pojave je da su vegetativne podloge za kalemljenje bile inficirane ovom bakterijom. Zbog toga je veoma bitno razvijati dijagnostičke protokole za utvrđivanje prisustva E. amylovora u podlogama za kalemljenje jabuke, tokom procesa kontrole zdravstvene ispravnosti sadnog materijala

Karakteristike sojeva bakterija roda Pseudomonas izolovanih iz obolelih grana šljive

Characteristics of Pseudomonas syringae strains isolated from diseased plum trees are presented is this paper. Based on pathogenic, biochemical and physiological characteristics, isolated starins were divided into two groups: First group of strains, isolated from diseased plum branches with symptoms of suden decay, was simillar to Pseudomonas syringae pv. syringae; second group of strains, isolated from necrotic flower buds on plum trees, exhibited characteristics simillar to Pseudomonas syringae pv. morsprunorum. In addition, phytopathogenic fungi belonging to genera Phomopsis, Botryosphaeria and Leucostoma, were also isolated from diseased plum trees. Further study of these pathogens and their role in the epidemiology of suden plum trees decay is in progress.U radu su prikazane karakteristike sojeva bakterije Pseudomonas syringae izolovanih iz nekrozom zahvaćenih tkiva šljive. Na osnovu patogenih i biohemijsko-fizioloških odlika proučavane izolate smo svrstali u dve grupe: I grupa sojeva izolovana je iz obolelih grana šljive sa simptomima sušenja i oni su prema svojim odlikama slični Pseudomonas syringae pv. syringae; II grupa sojeva izolovana je iz nekrotičnih cvetnih pupoljaka šljive i oni ispoljavaju karakteristike tipične za Pseudomonas syringae pv. morsprunorum. Iz obolelih grana šljive, pored ovih bakterija, izolovane su i gljive rodova Phomopsis, Botryosphaeria i Leucostoma. Dalja proučavanja ovih patogena i njihova uloga u pojavi iznenadnog sušenja mladih stabala šljive su u toku

Značaj prognozno-izveštajne službe u suzbijanju štetnih organizama u poljoprivredi

Према подацима ФАО светска производња пестици- да, од половине прошлог века, увећава се по стопи од око 11% годишње, од 0,2 милиона тона 50-их година прошлог века до више од 5 милиона тона до 2000. године. Овако велика производња и промет пестицида у најразвијени- јим деловима света последица је интензивирања пољопривредне производње и све већих потреба за храном. Свакако да је овај ниво потрошње пестици- да и резултат деловања биоагенаса у биљној производњи, односно све веће опасности од потенцијалних штета које могу изазвати проузроковачи биљ- них болести и штеточине пољопривредног биља. Међутим, често је употреба пестицида против штетних организама у биљној производњи прекомерна и неадекватна, па су последице које због тога настају, са здравственог, еколо- шког и економског аспекта, веома значајне. Због свега поменутог, прогноза појаве штетних организама у биљној производњи, као један од најважнијих сегмената заштите биља, још више добија на значају јер доприноси правовре- меној, адекватној и рационалној употреби хемијских средстава. Значајан део активности у овој области је у функцији проучавања биологије и екологије штетних организама и све то у циљу њиховог успешног, ефикасног и, што је могуће рационалнијег, сузбијања

Sorbus domestica i S.torminalis novi domaćini Erwinia amylovora u Srbiji

U radu su prikazani rezultati proučavnja izolovanih sojeva bakterije iz plamenjačom zahvaćenih mladara ukrasnih biljka Sorbus domestica i Sorbus torminalis. Proučavani sojevi su Gram negativni, ne stvaraju fluorescentni pigment na King-ovoj podlozi B, a glukozu metabolišu i oksidativno i fermentativno. Prouzrokuju HR duvana i nekrozu nesazrelih, inokulisanih plodova kruške (viljamova) praćenu obilnom produkcijom bakterijskog eksudata.. Prvi simptomi na inokulisanim mladarima biljaka domaćina u očavaju se posle 2-3 dana, ispoljavaju se u vidu vlažnih pega koje se vremenom šire zhavatjući ga u celosti Na osnovu patogenih, biohemijskih i seroloških odlika (ELISA) proučavanih izolata zaključeno je da patološke promene na ukrasnim biljkama Sorbus domestica i Sorbus torminalis prouzrokuje Erwinia amylovora. To je potvrđeno i primenom molekularne metode (PCR) korišćenjem specifičnog prajmera za bakteriju E. amylovora. Ovo je prvi nalaz E. amylovora na ukrsnim biljkama roda Sorbus u Srbij

Penicillium expansum as a postharvest pathogen of tomato fruit in Serbia

Tomato (Solanum lycopersicum, L.) is one of the most widely cultivated crops with high content of vitamins and antioxidant lycopene, which are very important for human health. During the growing season and postharvest storage tomato is susceptible to various diseases caused by pathogenic fungi. In July 2019, tomato (cv. Balkan) with symptoms of blue mold decay were collected from market in Belgrade, Serbia. Macroscopic morphology of three obtained monosporic isolates were observed after growth on Czapek yeast autolysate agar (CYA), creatine sucrose agar (CREA), and malt extract agar (MEA) for seven days at 25ºC. Also, selected isolates were incubated at 5, 25, and 37°C for one week on CYA to monitor the effect of different temperature incubation conditions. Colony characteristics and micromorphology of the fungi agreed with the literature descriptions of Penicillium expansum. The conidiophores of isolates were hyaline, mainly terverticillate; stipes usually smooth-walled; metulae and phialides cylindrical; conidia ellipsoidal (3-3,86-4 × 3-3,13-4 μm), greenish, smooth-walled. Total DNA was extracted using DNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and partial β-tubulin (BenA) sequence was amplified with primers Bt2a/Bt2b. BenA sequence of representative isolate ParP/1 was deposited in NCBI GenBank (Accession No. ON186699). Phylogenetic analysis clustered our isolate with other isolates of P. expansum. Pathogenicity test was conducted on symptomless, detached tomato fruits. All tested isolates caused typical blue mold symptoms on tomato fruits after seven days of incubation. To our knowledge, this is the first report of P. expansum causing postharvest fruit decay on tomato in Serbia

Ispitivanje kvaliteta semena ozime pšenice u periodu 2000-2005. godine

U radu su prikazani rezultati ispitivanja kvaliteta semena jedanaest sorti ozime pšenice: Pobeda, Evropa 90, NS Rana 5, Renesansa, Pesma, Proteinka, Balkan, KG-56, KG-100, Gruža i Takovčanka. Analizirano je 120 uzoraka semena ozime pšenice u prometu u periodu od 2000 do 2005 godine. Ocenjivani su sledeći parametri: procenat čistoće semena, masa 1000 semena, energija klijavosti, ukupna klijavost, vlažnost semena i broj zrna korova u 1000 grama semena. Seme je pripadalo kategoriji prve sortne reprodukcije. Rezultati su pokazali da je prosečna čistoća bila 99,3%, masa 1000 semena 41,4 g, energija klijanja 89%, ukupna klijavost 93%, vlažnost semena 11,9%, broj zrna korova u uzorcima je 0,5 i zdravstveno stanje ispravno, što zadovoljava zakonom propisane vrednosti

EPS-SJ exopolisaccharide produced by the strain Lactobacillus paracasei subsp. paracasei BGSJ2-8 is involved in adhesion to epithelial intestinal cells and decrease on E. coli association to Caco-2 cells

The aim of this study was to determine the role of an exopolysaccharide produced by natural dairy isolate Lactobacillus paracasei subsp. paracasei BGSJ2-8, in the adhesion to intestinal epithelial cells and a decrease in Escherichia coli's association with Caco-2 cells. Annotation of the BGSJ2-8 genome showed the presence of a gene cluster, epsSJ, which encodes the biosynthesis of the strain-specific exopolysaccharide EPS-SJ, detected as two fractions (P1 and P2) by size exclusion chromatography (SEC) coupled with multi-angle laser light scattering (MALLS) detection. SEC-MALLS analysis revealed that an EPS-SJ- mutant (EPS7, obtained by insertion mutagenesis of the glps_2198 gene encoding primary glycosyltransferase) does not produce the P2 fraction of EPS-SJ. Transmission electron microscopy showed that EPS7 mutant has a thinner cell wall compared to the EPS-SJ strain BGSJ2-83 (a plasmid free-derivative of BGSJ2-8). Interestingly, strain BGSJ2-83 showed higher adhesion to Caco-2 epithelial intestinal cell line than the EPS7 mutant. Accordingly, BGSJ2-83 effectively reduced E. coli ATCC25922's association with Caco-2 cells, while EPS7 did not show statistically significant differences. In addition, the effect of EPS-SJ on the proliferation of lymphocytes in gastrointestinal associated lymphoid tissue (GALT) was tested and the results showed that the reduction of GALT lymphocyte proliferation was higher by BGSJ2-83 than by the mutant. To the best of our knowledge this is the first report indicating that the presence of EPS (EPS-SJ) on the surface of lactobacilli can improve communication between bacteria and intestinal epithelium*Implying its possible role in gut colonization.Peer Reviewe

Uticaj ugljenika i azota na porast izolata Colletotrichum spp

In Serbia, the occurrence of anthracnose on pear, apple, sour cherry, and tomato fruits has been recorded during the last several years. Colletotrichum spp. were isolated from all diseased fruits. Twenty monoconidial isolates were selected for comparative studies, and the reference strains of C. acutatum (CBS 294.67) and C. gloeosporioides (CBS 516.97) were used as a control. The physiological studies have included the investigation of the effect of different sources of carbon and nitrogen on growth of C. acutatum and C. gloeosporioides. The results indicated that carboxymethyl cellulose was the most appropriate source of carbon for the growth of isolates of Colletottrichum spp. Of the three nitrogen sources studied, the best growth of all tested fungi was recorded on the media with casein hydrolysate

Comparative analysis of pseudomonas population in oil-contaminated soils in Serbia and plant - pathogenic pseudomonas

Pseudomonas species are remarkable for their capacity to colonize almost all terrestrial and aquatic ecological niches. This genus includes species of ecological, economic and health-related importance. Although they are globally active in aerobic decomposition and biodegradation, Pseudomonas includes species pathogenic for humans, domestic animals and cultivated plants. The aim of this study was to identify members of the Pseudomonas species from oil-polluted soil, investigate their diversity and compare it to phytopatogenic strains isolated from host-plants near marked site. Isolates were described phenotypically according to carbon assimilation, fluorescence on King B medium and susceptibility patterns to 5 different heavy metals. In addition, they were characterized genotypically using plasmid profile and fingerprints obtained with the (GTG)5 primer. We have observed high heterogeneity within the Pseudomonas strains collected from oil- contaminated soils. Phenotyping and (GTG)5 pattern showed that similarities between strains ranged from 55% to 94%, with some strains showing high level of similarity with plant-pathogens