Publications

4424

Abstract“Candidatus Liberibacter solanacearum” (Lso) are phloem‐restricted and unculturable Gram‐negative bacteria. Presently five haplotypes have been identified worldwide; but only haplotypes A and B are associated with the vector Bactericera cockerelli (Šulc.) in the Americas. Previous studies showed that Lso‐infection reduces B. cockerelli reproductive output and that Lso haplotype B is more pathogenic than Lso haplotype A. To understand the interaction of Lso haplotype B and B. cockerelli, the fitness of Lso‐free and Lso B‐infected insects, and the expression of vitellogenin (BcVg1‐like), a gene involved directly in the insect reproduction were analyzed. Statistical differences in the number of eggs oviposited, and the total number of progeny nymphs and adults were found among crosses of insects with or without Lso. Significant differences in sex proportions were found between Lso B‐infected and Lso‐free crosses: a higher proportion of F1 adult females were obtained from Lso B‐infected mothers. A significant reduction of BcVg1‐like was observed in crosses performed with Lso B‐infected females compared to the Lso‐free insects. In female cohorts of different age, a significant reduction of BcVg1‐like expression was measured in 7‐d‐old Lso B‐infected females (virgin and mated) compared with 7‐d‐old Lso‐free females (virgin and mated), respectively. The reduction of BcVg1‐like transcript was associated with a lower number of developing oocytes observed in female's reproductive systems. Overall, this study represents the first step to understand the interaction of Lso B with B. cockerelli, highlighting the effect of Lso B infection on egg production, BcVg1‐like expression, and oocyte development.

AbstractA previously unknown haplotype of the plant pathogen ‘CandidatusLiberibacter solanacearum’ (Lso) was found in cultivated carrots and parsnips in eastern Finland. That same haplotype was found in western Finland, over 300 km away, in the family Polygonaceae, the speciesFallopia convolvulus(wild buckwheat) andPersicaria lapathifolia(pale persicaria) growing as weeds within carrot and parsnip fields. The infected plants, both apiaceous and polygonaceous, showed symptoms of foliar discolouration. This is the first report of Lso bacteria in plants of the family Polygonaceae. The finding that the polygonaceous plants infected with a previously unknown haplotype of Lso were growing among the apiaceous plants infected with Lso haplotype C suggests that these two haplotypes might be transmitted by different vectors. Phylogenetic analyses showed that the new haplotype, called haplotype H, is distinct from the previously characterized haplotypes and appears to have diverged early from their common ancestor. Multi-locus sequence analysis revealed four different sequence types (strains) within the haplotype H. These findings suggest that the haplotype H is likely to be endemic in northern Europe and that the genetic diversity within the Lso species is higher than previously assumed.

Chain elongation by medium-chain fatty acid (MCFA)-producing microbiomes offers an opportunity to produce valuable chemicals from organic streams that would otherwise be considered waste. However, the physiology and energetics of chain elongation are only beginning to be studied, and many of these organisms remain uncultured. We analyzed MCFA production by two uncultured organisms that were identified as the main MCFA producers in a microbial community enriched from an anaerobic digester; this characterization, which is based on meta-multi-omic analysis, complements the knowledge that has been acquired from pure-culture studies. The analysis revealed previously unreported features of the metabolism of MCFA-producing organisms.

AbstractHolospora-like bacteria are obligate intracellularAlphaproteobacteria, inhabiting nuclei ofParameciumciliates and other protists.Alphaproteobacteriahave drawn significant attention, as both closest existing relatives of bacteria that gave rise to mitochondria, as well as a class of intracellular bacteria with numerous important pathogens.HLB clade includes two genera –Holospora(Hafkine 1980) andcandidatusGortzia (Boscaro 2013). These bacteria have a peculiar life cycle with two morphological forms, a strict specificity to the host species and the type of nucleus they inhabit.Here we describe a new species of HLB –candidatusGortzia yakutica sp. nov., a symbiont from macronucleus ofParamecium putrinum, the first known HLB for thisParameciumspecies. The new symbiont shows morphological similarities with other HLB. The phylogenetic analysis of SSU rDNA gene places it intocandidatusGortzia clade.