Proliferacija jabuke (apple proliferation; AP) je bolest uzrokovana bakterijom ‘Candidatus Phytoplasma mali' koja je prisutna i rasprostranjena u većini europskih zemalja. Iako zaraza ne dovodi do potpunog propadanja biljke-domaćina, zbog značajnog smanjenja veličine i kvalitete plodova ekonomski gubici su značajni. Fitoplazme (rod ‘Candidatus Phytoplasma') su unutarstanični, pleomorfni biljni patogeni iz razreda Mollicutes. Smještene su u žilnom staničju zaražene biljke, a umnažaju se i žive samo unutar sitastih cijevi floema biljke i stanica kukaca. Bolest se prenosi zaraženim sadnim materijalom i kukcima – vektorima iz reda Hemiptera. Kako je još uvijek gotovo nemoguće uzgojiti čistu kulturu fitoplazmi na umjetnom mediju, za karakterizaciju se koristi metoda multigenske tipizacije. Uzročnik bolesti, ‘Candidatus Phytoplasma mali' tek je nedavno u Hrvatskoj po prvi puta identificiran molekularnim metodama. U ovom diplomskom radu glavni cilj bio je karakterizirati novootkrivene izolate bakterije 'Ca. Phytoplasma mali' iz zaraženog tkiva jabuke i kukca-vektora Cacopsylla picta analizom gena secY i imp. Fragmenti ovih gena umnoženi su metodom PCR korištenjem specifičnih početnica te su sekvencirani. Prisutnost zaraze fitoplazmom 'Ca. Phytoplasma mali' dokazana je umnažanjem i restrikcijskom analizom gena za 16S rRNA. Filogenetskom analizom dobivenih nukleotidnih sljedova dobiveni su podaci o varijabilnosti ovih gena kao i njihovoj srodnosti s izolatima iz čitavog svijeta. Rezultati analize varijabilnosti dodatnih molekularnih markera uz 16S rRNA važni su za razjašnjavanje molekularne epidemiologije, posebno stoga što se ova fitoplazma prenosi kukcima – vektorima iz roda Cacopsylla koje su prisutne u Hrvatskoj.

Apple poliferation (AP) is a disease caused by 'Candidatus Phytoplasma mali' that is present and widespread in most European countries. Although infection does not lead to the degradation of plant hosts, due to a significant reduction in the size and quality of the fruits of economic losses are significant. Phytoplasma (genus 'Candidatus Phytoplasma') are intracellular, pleomorphic plant pathogens from the class Mollicutes. They are located in the core of tissues of infected plants are propagated and live only in the phloem plant and insect cells. Disease is transmitted by infected planting material and insects - vectors of the order Hemiptera. As it is still almost impossible to obtain pure culture of phytoplasma in an artificial medium, multigene characterization in often used for their characterization. 'Ca. Phytoplasma mali' has only recently been identified in Croatia for the first time by molecular methods. This thesis main objective is to characterize the newly discovered 'Ca. Phytoplasma mali' isolates from infected tissue apples and insect-vector Cacopsylla picta analysis of gene secY and imp. The presence of phytoplasma infection 'Ca. Phytoplasma mali' was demonstrated by amplification and restriction analysis of 16S rRNA.Fragments of these genes were amplified by PCR using specific primers and sequenced. Phylogenetic analysis of the nucleotide sequences obtained provided information on the variability of these genes as well as their relatedness to already described isolates. Results of the analysis of variability of additional molecular markers to the 16S rRNA are important for elucidating the molecular epidemiology, especially because this phytoplasma is transmitted by insects of the genus Cacopsylla that are present in Croatia.