Manipulation of Plant Defense Responses by the Tomato Psyllid (Bactericerca cockerelli) and Its Associated Endosymbiont Candidatus Liberibacter Psyllaurous

Some plant pathogens form obligate relationships with their insect vector and are vertically transmitted via eggs analogous to insect endosymbionts. Whether insect endosymbionts manipulate plant defenses to benefit their insect host remains unclear. The tomato psyllid, Bactericerca cockerelli (Sulc), vectors the endosymbiont “Candidatus Liberibacter psyllaurous” (Lps) during feeding on tomato (Solanum lycopersicum L.). Lps titer in psyllids varied relative to the psyllid developmental stage with younger psyllids harboring smaller Lps populations compared to older psyllids. In the present study, feeding by different life stages of B. cockerelli infected with Lps, resulted in distinct tomato transcript profiles. Feeding by young psyllid nymphs, with lower Lps levels, induced tomato genes regulated by jasmonic acid (JA) and salicylic acid (SA) (Allene oxide synthase, Proteinase inhibitor 2, Phenylalanine ammonia-lyase 5, Pathogenesis-related protein 1) compared to feeding by older nymphs and adults, where higher Lps titers were found. In addition, inoculation of Lps without insect hosts suppressed accumulation of these defense transcripts. Collectively, these data suggest that the endosymbiont-like pathogen Lps manipulates plant signaling and defensive responses to benefit themselves and the success of their obligate insect vector on their host plant

Antiviral efficacy of nanoparticulate vacuolar ATPase inhibitors against influenza virus infection

Che-Ming Jack Hu,1,2,* You-Ting Chen,3,* Zih-Syun Fang,1,3 Wei-Shan Chang,3 Hui-Wen Chen2,3 1Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan; 2Research Center for Nanotechnology and Infectious Diseases, Taipei, Taiwan; 3Department of Veterinary Medicine, National Taiwan University, Taipei, Taiwan *These authors contributed equally to this work Background: Influenza virus infections are a major public health concern worldwide. Conventional treatments against the disease are designed to target viral proteins. However, the emergence of viral variants carrying drug-resistant mutations can outpace the development of pathogen-targeting antivirals. Diphyllin and bafilomycin are potent vacuolar ATPase (V-ATPase) inhibitors previously shown to have broad-spectrum antiviral activity. However, their poor water solubility and potential off-target effect limit their clinical application. Methods: In this study, we report that nanoparticle encapsulation of diphyllin and bafilomycin improves the drugs’ anti-influenza applicability. Results: Using PEG-PLGA diblock copolymers, sub-200 nm diphyllin and bafilomycin nanoparticles were prepared, with encapsulation efficiency of 42% and 100%, respectively. The drug-loaded nanoparticles have sustained drug release kinetics beyond 72 hours and facilitate intracellular drug delivery to two different influenza virus-permissive cell lines. As compared to free drugs, the nanoparticulate V-ATPase inhibitors exhibited lower cytotoxicity and greater in vitro antiviral activity, improving the therapeutic index of diphyllin and bafilomycin by approximately 3 and 5-fold, respectively. In a mouse model of sublethal influenza challenge, treatment with diphyllin nanoparticles resulted in reduced body weight loss and viral titer in the lungs. In addition, following a lethal influenza viral challenge, diphyllin nanoparticle treatment conferred a survival advantage of 33%. Conclusions: These results demonstrate the potential of the nanoparticulate V-ATPase inhibitors for host-targeted treatment against influenza. Keywords: influenza virus, vacuolar ATPase inhibitor, diphyllin, bafilomycin, nanoparticle

How plants might recognize rhizospheric bacterial volatiles

In contrast to animals, plants possess neither olfactory organs nor a central nervous system. However, they do perceive and systemically react to volatile stimuli. Such function serves in monitoring the immediate and remote environments and translates into optimized responses to biotic and abiotic stresses. While the ecological relevance of volatile-mediated plant–plant and plant–insect interactions is today unquestioned, both above- and below-ground plant–microbe communication through VOCs has only gained attention recently. The common metabolic origins that yield the vast chemical diversity of plant and microbes allow for a substantial overlap between plant and microbial volatile species. Hence, it remains unclear if plants recognize and/or distinguish plant-like from foreign cues. The identities of the cellular components ensuring such recognition are even more obscure. Easy-to-score plant outputs in response to microbial VOCs elicitation, like plant growth promotion and innate immunity stimulation, will be instrumental to pinpointing VOCs-sensing proteins. Several major phytohormones have a gaseous nature and dedicated perception machineries that could serve as a basis to envisage how volatile semiochemicals might be sensed by plants. If volatile-mediated communication represents an ancestral cellular feature, VOCs perception and signalling might rely on basal protein families and define a universal chemical language