Publications

4476

AbstractPhytoplasmas are specialized small bacteria restricted to the phloem tissue and spread by hemipterans feeding on plant sieve tube elements. As for many other plant pathogens, it is known that phytoplasmas alter the chemistry of their hosts. Most research on phytoplasma-plant interactions focused on the induction of plant volatiles and phytohormones. Little is known about the influence of phytoplasma infections on the nutritional composition of phloem and consequences on vector behavior and development. The plum psyllidCacopsylla prunitransmits ‘CandidatusPhytoplasma prunorum’, the causing agent of European Stone Fruit Yellows (ESFY). While severalPrunusspecies are susceptible for psyllid feeding, they show different responses to the pathogen. We studied the possible modulation of plant-insect interactions by bacteria-induced changes in phloem sap chemistry. Therefore, we sampled phloem sap from phytoplasma-infected and non-infectedPrunus persicaandPrunus insititiaplants, which differ in their susceptibility to ESFY and psyllid feeding. Furthermore, the feeding behavior and development ofC. pruninymphs was compared on infected and non-infectedP. persicaandP. insititiaplants. Phytoplasma infection did not affect phloem consumption byC. pruninymphs nor their development time. In contrast, the study revealed significant differences betweenP. insititiaandP. persicain terms of both phloem chemistry and feeding behavior ofC. pruninymphs.Phloem feeding phases were four times longer onP. insititiathan onP. persica, resulting in a decreased development time and higher mortality of vector insects onP. persicaplants. These findings explain the low infestation rates of peach cultivars with plum psyllids commonly found in field surveys.

AbstractAnaplasmataceae agents are obligatory intracellular Gram-negative α-proteobacteria that are transmitted mostly by arthropod vectors. Although mammals of the Superorder Xenarthra (sloths, anteaters, and armadillos) have been implicated as reservoirs for several zoonotic agents, only few studies have sought to detect Anaplasmataceae agents in this group of mammals. This study aimed to investigate the occurrence and genetic diversity ofAnaplasmaspp. andEhrlichiaspp. in blood and spleen samples of free-living Xenarthra from four different states in Brazil (São Paulo, Mato Grosso do Sul, Rondônia, and Pará). Nested and conventional PCR screening assays were performed to detect therrsanddsbgenes ofAnaplasmaspp. andEhrlichiaspp., respectively. The assays were positive in 27.57% (91/330) of theAnaplasmaspp. and 24.54% (81/330) of theEhrlichiaspp. Of the 91 positiveAnaplasmaspp. samples, 56.04% were positive in a conventional PCR assay targeting the 23S–5S intergenic region. Phylogenetic and distance analyses based on therrsgene allocatedAnaplasmasequences from sloths captured in Rondônia and Pará states in a single clade, which was closely related to theA. marginale,A. ovis,andA. capraclades. The sequences detected in southern anteaters from São Paulo were allocated in a clade closely related to sequences ofAnaplasmaspp. detected inNasua nasua,Leopardus pardalis, andCerdocyon thousin Brazil. These sequences were positioned close toA. odocoileisequences. Genotype analysis corroborated previous findings and demonstrated the circulation of two distinctAnaplasmagenotypes in animals from north and southeast Brazil. The first genotype was new. The second was previously detected inN. nasuain Mato Grosso do Sul state. The intergenic region analyses also demonstrated two distinct genotypes ofAnaplasma. The sequences detected in Xenarthra from Pará and Rondônia states were closely related to those inA. marginale,A. ovis,andA. capra.Anaplasmaspp. sequences detected in Xenarthra from São Paulo and were allocated close to those inA. phagocytophilum. The analyses based on thedsbgene grouped theEhrlichiaspp. sequences with sequences ofE. canis(São Paulo, Mato Grosso do Sul, and Pará) andE. minasensis(Rondônia and Pará). The data indicate the occurrence ofE. canisandE. minasensisand two possible newCandidatusspecies ofAnaplasmaspp. in free-living mammals of the Superorder Xenarthra in Brazil.

‘Candidatus Liberibacter asiaticus’ (CLas) is a major causal agent of citrus Huanglongbing (HLB), which is transmitted by Asian citrus psyllid (ACP), Diaphorina citri, causing severe losses in various regions of the world. Vector efficiency is higher when acquisition occurs by ACP immature stages and over longer feeding periods. In this context, our goal was to evaluate the progression of CLas population and infection rate over four ACP generations that continuously developed on infected citrus plants. We showed that the frequency of CLas-positive adult samples increased from 42% in the parental generation to 100% in the fourth generation developing on CLas-infected citrus. The bacterial population in the vector also increased over generations. This information reinforces the importance of HLB management strategies, such as vector control and eradication of diseased citrus trees, to avoid the development of CLas-infected ACP generations with higher bacterial loads and, likely, a higher probability of spreading the pathogen in citrus orchards.

Abstract This protocol describes a rapid protein extraction method for the archaeon Candidatus Vulcanisaeta moutnovskia, which can be also implemented for other archaea. The utilization of two different methods for protein extraction constitute the main step of the protocol. Method I involves the extraction with a multi-chaotropic lysis buffer containing a non-denaturing zwitterionic detergent, most efficient for extracting cytosolic proteins. Method II involves a denaturing anionic detergent allowing total disruption of the membranes and capable of extracting both membrane (hydrophobic) and non-membrane (water-soluble, hydrophilic) proteins. The big advantage of the methods is to use general laboratory chemicals to make powerful extraction buffers, resulting in high quality and quantity of proteins. The methods probably are usable for any other archaea or microbial cells, and takes about 14-22 h. Following extraction and further protein digestion, 1D-nano Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometric (LC ESI-MSMS) analysis with Triple TOF 5600 and Orbitrap technologies were used for protein identification and further quantification.

AbstractScientific exploration of phototrophic bacteria over nearly 200 years has revealed large phylogenetic gaps between known phototrophic groups that limit understanding of how phototrophy evolved and diversified. Through Boreal Shield lake water incubations, we cultivated an anoxygenic phototrophic bacterium from a previously unknown order within theChloroflexotaphylum that represents a highly novel transition form in the evolution of photosynthesis. Unlike all other known phototrophs, this bacterium uses a Type I reaction center (RCI) for light energy conversion yet belongs to the same bacterial phylum as organisms that use a Type II reaction center (RCII) for phototrophy. Using physiological, phylogenomic, and environmental metatranscriptomic data, we demonstrate active RCI-utilizing metabolism by the strain alongside usage of chlorosomes and bacteriochlorophylls related to those of RCII-utilizingChloroflexotamembers. Despite using different reaction centers, our phylogenomic data provide strong evidence that RCI- and RCII-utilizingChloroflexiamembers inherited phototrophy from a most recent common phototrophic ancestor that used RCI, RCII, or both reaction center classes, substantially revising our view of the diversity and evolution of phototrophic life. TheChloroflexotaphylum preserves an evolutionary record of interaction between RCI and RCII among anoxygenic phototrophs that gives new context for exploring the origins of phototrophy on Earth.