Diverzitet kompleksa vrste Fusarium graminearum patogena strnih žita i kukuruza u Srbiji

Abstract

Za proučavanje diverziteta vrste F. graminearum odabran je 101 izolat iz kolekcije Laboratorije za fitopatologiju Instituta za kukuruz "Zemun Polje" koji su prethodno identifikovani konvencionalnim metodama na osnovu makroskopskih i mikroskopskih svojstava. Izolati su prikupljeni u periodu od 1993. do 2015. godine, a poreklom iz uzoraka pšenice (42), kukuruza (37) i ječma (22) iz 41 lokaliteta na teritoriji Srbije. Sa ciljem da se dobije uvid o rasprostranjenosti, prisustvu i diverzitetu vrsta Fusarium graminearum kompleksa (Fg) kao i o trihotecenskim hemotipovima u Srbiji, obavljena su proučavanja morfoloških, patogenih, toksigenih i filogenetskih svojstava odabranih izolata. Na osnovu svih proučenih svojstava utvrđeno je prisustvo tri vrste u okviru Fg kompleksa: Fusarium graminearum sensu stricto, Fusarium boothii i Fusarium vorosii. Po prvi put u Srbiji, detektovano je prisustvo F. boothii i F. vorosii patogena strnih žita i kukuruza u našoj zemlji. Na osnovu morfoloških, patogenih i toksigenih svojstava uočen je veliki diverzitet ispitivanih izolata. Rezultati analize morfoloških svojstava izolata F. graminearum ss, F. boothii i F. vorosii, ukazuju da ne postoje razlike među njima. Izolati vrste F. boothii i F. vorosii ispoljili su generalno slabiju patogenost u poređenju sa ostalim izolatima. Analiza potencijala produkcije mikotoksina deoksinivalenola i zearalenona ELISA i HPLC metodom ukazala je na varijabilnost između ispitivanih izolata. Određivanjem trihotecenskih hemotipova hemijskom analizom utvrđeno je da u Srbiji postoje dva hemotipa - 15ADON (dominantan) i 3ADON. Za razliku od hemijskih, molekularnim analizama na osnovu TRI3 i TRI12 gena, utvrđeno je prisustvo samo 15ADON hemotipa. Dobijeni rezultati o biodiverzitetu hemotipova su prvi nalaz u agroekološkim uslovima Srbije. Analiza nukleotidnih sekvenci tri genomska regiona (TEF−1α, β−tubulin i histon H3), pokazala je da postoje različiti potencijali za razdvajanje vrsta u okviru Fg kompleksa. Rezultati ove disertacije ukazali su na postojanje dve vrste u okviru Fg kompleksa (F. boothii i F. vorosii), koje do sada nisu identifikovane na teritoriji Srbije. Sekvenciranje ovih genomskih regiona odabranih izolata i njihovo poređenje sa referentnim izolatima kao i poređenje sa izolatima Fg kompleksa u svetu doprinelo je boljem poznavanju biodiverziteta ovih vrsta u Srbiji.

One hundred and one isolates of the F. graminearum species have been isolated from the collection of the Laboratory of Phytopathology of the Maize Research Institute, Zemun Polje to study the species diversity. These isolates had been previously identified using conventional methods based on macroscopic and microscopic properties. Isolates, originating from samples of wheat (42), maize (37) and barley (22), were collected from 41 locations in Serbia in the period from 1993 to 2015. In order to gain insight into the distribution, presence and diversity of the Fusarium graminearum species complex (Fg), as well as into thrichotecene chemotypes in Serbia, studies of the morphological, pathogenic, toxigenic and phylogenetic properties of the selected isolates were carried out. According to all observed properties, the presence of the three following species was determined within the Fg complex: Fusarium graminearum sensu stricto, Fusarium boothii and Fusarium vorosii. F. boothii and F. vorosii, pathogens of small grains and maize in our country, were detected for the first time in Serbia. Based on morphological, pathogenic and toxigenic properties, a great diversity of analysed isolates was observed. Results of analyses of morphological properties of the isolates of F. graminearum ss, F. boothii and F. vorosii, pointed out that there had been no differences among them. Isolates of F. boothii and F. vorosii species exhibited generally less pathogenicity than remaining isolates. The analysis of the potential for the production of mycotoxins deoxynivalenol and zearalenone by the ELISA and the HPLC method pointed out to the variability among analysed isolates. The determination of trichothecene chemotypes done by chemical analyses confirmed the presence of two chemotypes in Serbia- 15ADON (dominant) and 3ADON. In contrast to chemical analyses, the molecular analyses, based on the TRI3 and TRI12 genes, established the presence of only 15ADON chemotype. The obtained results on the biodiversity of chemotypes are the first finding under agroecological conditions of Serbia. The analysis of nucleotide sequences of the three genomic regions (TEF−1α, β−tubulin and histone H3), showed the existence of different potentials for separation of species within the Fg complex. The results presented in this PhD thesis point out to the existence of two species (F. boothii and F. vorosii) within the Fg complex, which have not yet been identified in the territory of Serbia. Sequencing these portions of the genome of the selected isolates and their comparison with the reference isolates, as well as, the comparison with the Fg complex isolates in the world contributed to a better knowledge of the biodiversity of these species in Serbia.