Adult Influence on Juvenile Phenotypes by Stage-Specific Pheromone Production

Abstract

SummaryMany animal and plant species respond to population density by phenotypic plasticity. To investigate if specific age classes and/or cross-generational signaling affect density-dependent plasticity, we developed a dye-based method to differentiate co-existing nematode populations. We applied this method to Pristionchus pacificus, which develops a predatory mouth form to exploit alternative resources and kill competitors in response to high population densities. Remarkably, adult, but not juvenile, crowding induces the predatory morph in other juveniles. High-performance liquid chromatography-mass spectrometry of secreted metabolites combined with genetic mutants traced this result to the production of stage-specific pheromones. In particular, the P. pacificus-specific di-ascaroside#1 that induces the predatory morph is induced in the last juvenile stage and young adults, even though mouth forms are no longer plastic in adults. Cross-generational signaling between adults and juveniles may serve as an indication of rapidly increasing population size, arguing that age classes are an important component of phenotypic plasticity.

Influence of environmental temperature on mouth-form plasticity in Pristionchus pacificus acts through daf-11-dependent cGMP signaling

“…Our findings reveal that temperature has a strong effect on the mouth-form decision. Together with previous studies, these results indicate that P. pacificus decides which mouth-form to execute mainly in response to pheromones (Bose et al, 2012;Werner et al, 2018b), nutrient conditions (Werner et al, 2017) and temperature (this study). Thus, like dauer formation in C. elegans (Golden and Riddle, 1984) and P. pacificus (Ogawa et al, 2009), mouth-form plasticity is regulated by a set of biotic and abiotic factors.…”

“…For example, Ppa-daf-19, the RTX master transcriptional regulator of ciliogenesis has no dauer phenotype in the RS2333 background (Moreno, Lenuzzi et al, 2018). To clarify this point further, more detailed analyses of dauer formation have to be performed using the various available dauer-induction protocols in P. pacificus (Markov et al, 2016;Werner et al, 2018b) -a project which is clearly outside of the scope of the current manuscript.…”

Conserved nuclear hormone receptors controlling a novel plastic trait target fast-evolving genes expressed in a single cell

“…The wild-type P. pacificus strain PS312 preferentially forms Eu morphs in standard culture conditions on agar plates, but becomes predominantly St in liquid culture [19]. Additionally, nematode-derived modular metabolites excreted by adult animals induce the predatory Eu morph [20,21]. A forward genetic screen identified the sulfatase gene eud-1 as a developmental switch confirming long-standing predictions that plastic traits are regulated by binary switches [18].…”

Nematode biphasic ‘boom and bust’ dynamics are dependent on host bacterial load while linking dauer and mouth‐form polyphenisms

“…Furthermore, the complex NDMM dasc#1 specific to P. pacificus strongly influences mouth form (Bento et al, 2010;Bose et al, 2012). Interestingly, this molecule is produced almost exclusively by adults and induces juveniles to develop the predatory morph in a density-dependent manner (Werner et al, 2018). Future long-term studies with even more sophisticated setups are necessary to reveal the chemistry associated with these observations.…”

“…1C), that in addition to bacterial feeding, allows for predation on both fungi and other nematodes (Susoy and Sommer, 2016;Sudhaus 2010;Ragsdale et al, 2013). Like dauer, mouth form is also influenced by population density and environmental conditions, including food availability and age-class-dependent crowding effects (Sanghvi et al, 2016;Werner et al, 2017;Werner et al, 2018). Thus, the decomposing beetle carcass teeming with assorted bacteria and nematodes is an ideal system to study the intricacies of multivariate symbioses and their effects on plasticity and niche construction.…”