Serratia symbiotica Enhances Fatty Acid Metabolism of Pea Aphid to Promote Host Development

Abstract

Bacterial symbionts associated with insects are often involved in host development and ecological adaptation. Serratia symbiotica, a common facultative endosymbiont harbored in pea aphids, improves host fitness and heat tolerance, but studies concerning the nutritional metabolism and impact on the aphid host associated with carrying Serratia are limited. In the current study, we showed that Serratia-infected aphids had a shorter nymphal developmental time and higher body weight than Serratia-free aphids when fed on detached leaves. Genes connecting to fatty acid biosynthesis and elongation were up-regulated in Serratia-infected aphids. Specifically, elevated expression of fatty acid synthase 1 (FASN1) and diacylglycerol-o-acyltransferase 2 (DGAT2) could result in accumulation of myristic acid, palmitic acid, linoleic acid, and arachidic acid in fat bodies. Impairing fatty acid synthesis in Serratia-infected pea aphids either by a pharmacological inhibitor or through silencing FASN1 and DGAT2 expression prolonged the nymphal growth period and decreased the aphid body weight. Conversely, supplementation of myristic acid (C14:0) to these aphids restored their normal development and weight gain. Our results indicated that Serratia promoted development and growth of its aphid host through enhancing fatty acid biosynthesis. Our discovery has shed more light on nutritional effects underlying the symbiosis between aphids and facultative endosymbionts.

Effects of Host Plant and Insect Generation on Shaping of the Gut Microbiota in the Rice Leaffolder, Cnaphalocrocis medinalis

“…Enterobacteriaceae is one of the important dominant taxa in the gut microbiota of many insects ( Wang et al, 2014 ; Yun et al, 2018 ; Raza et al, 2020 ). Enterobacteriaceae are involved in insect metabolism ( Pers and Hansen, 2021 ; Zhou et al, 2021 ), insect resistance or susceptibility to parasites, and pathogens and insecticides ( Oliver et al, 2003 ; Álvarez-Lagazzi et al, 2021 ; Polenogova et al, 2021 ) and play an important role in the host adaptability and reproduction of insects ( Shi et al, 2012 ; Wang et al, 2020b ). Pectobacterium , a clade of Enterobacteriaceae , is known as a function of nitrogen fixation ( Behar et al, 2005 , 2008 ).…”

The Key Role of Fatty Acid Synthase in Lipid Metabolism and Metamorphic Development in a Destructive Insect Pest, Spodoptera litura (Lepidoptera: Noctuidae)

“…For example, the level of triglyceride was severely decreased after knocking down FAS1 in the mosquito Aedes aegypti [ 11 ]. In Serratia-infected Acyrthosiphon pisum , the triglyceride content was reduced by feeding with dsFASN1 compared with the control [ 29 ]. Therefore, the present study demonstrates that FAS is not only responsible for fatty acid synthesis, but also affects the lipid dynamic in insects.…”

Cross-Talk Between Intestinal Microbiota and Host Gene Expression in Gilthead Sea Bream (Sparus aurata) Juveniles: Insights in Fish Feeds for Increased Circularity and Resource Utilization

“…Here, this can be exemplified by the lipogenic scd1a and scd1b enzymes, which becomes especially interesting in the case of scd1a given that a recent study revealed reliable epigenetic mechanisms (changes in DNA methylation rates of the scd1a promoter) by which the nutrition of parents can shape the s cd1a gene expression in the gilthead sea bream offspring (Perera et al, 2020 ). The extent to which this can be favored by changes in the gut microbiota remains unknown, but interestingly, the up-regulation of scd1 genes in the fish fed with the non-PAP diet was associated with OTUs assigned to Serratia nematodiphila (NoPAP, 1.02%) and Brevinema andersonii (NoPAP 0.1%; CTRL and PAP <0.01%), giving these taxa a role as intestinal SCFA producers in humans (Parada Venegas et al, 2019 ) and enhancers of fatty acid metabolism in insects (Zhou et al, 2021 ). The case of B. andersonii merits further attention, as this species belongs to Spirochaetesphylum, which colonizes the gut gilthead sea bream microbiome to a large extent with advancing age (11% in 4-year-old individuals) (Piazzon et al, 2019 ).…”