engleski

QUEST FOR PUTATIVE EFFECTORS OF 'CANDIDATUS PHYTOPLASMA SOLANI': TOWARDS UNDERSTANDING OF A SUCCESSFULL AND ADAPTABLE PATHOGEN

During the co-evolution of microbial pathogens and their hosts, pathogens developed a wide array of effectors – powerful molecular weapons increasing their virulence by disturbing hosts’ developmental processes and immune system. The term effector usually denotes a small secreted protein interacting with host cell ; however, effectors can include toxins, elicitors, analogues of (phyto)hormones and different enzymes. Phytoplasmas (genus ‘Candidatus Phytoplasma’) are endocellular wall-less bacteria with small genomes affecting numerous plant species and causing significant damage in agriculture worldwide. They have a dual parasitic cycle colonizing plant phloem and insect cells. Due to the inability of obtaining a pure culture in vitro, studies related to their pathogenicity mechanisms are still hindered. However, the ascent of metagenomic era and new technologies delivered new tools and possibilities for finding potential effectors. ‘Ca. P. solani’ is a cosmopolitan pathogen with a broad host range transmitted by many insect species and one of the most important phytoplasmas in Croatia. The aim this study was to sequence two ‘Ca. P. solani’ strains in order to get insight into their pathogenic potential and the repertoire of putative effectors. Whole plant samples of periwinkle infected with ‘Ca. P. solani’ were used for generation of libraries sequenced on Illumina MiSeq and MinION nanopore sequencing platforms. Raw reads were mapped to the reference genome and reads originating from periwinkle were filtered out. De novo assembly was performed as well as whole genome alignment and comparative analyses. Two draft genomes were generated with total size of 647, 316 bp (ST19) and 668, 749 bp (STOL) and longest contigs of 140, 634 bp and 158, 078 bp, respectively. Whole genome alignment with reference SA-1 revealed synteny and conserved gene order. Prediction and search for putative effectors showed the presence of homologues of SAP11 and SAP54 effectors as well as some putative effectors that were strain specific. Nonetheless, sequencing and comparative genome analyses of ‘Ca. P. solani’ genomes confirmed their highly repetitive nature and the presence of diverse putative effectors as a mechanism for successful adaptation and pathogenicity of this versatile pathogen.

effectors, phytoplasma, HTS, NGS, genome, sequencing

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