The condensation of nuclear promyelocytic leukemia bodies, cytoplasmic P-granules, P-bodies (PBs), and stress granules is reversible and dynamic via liquid–liquid phase separation. Although each condensate comprises hundreds of proteins with promiscuous interactions, a few key scaffold proteins are required. Essential scaffold domain sequence elements, such as poly-Q, low-complexity regions, oligomerizing domains, and RNA-binding domains, have been evaluated to understand their roles in biomolecular condensation processes. However, the underlying mechanisms remain unclear. We analyzed Nst1, a PB-associated protein that can intrinsically induce PB component condensations when overexpressed. Various Nst1 domain deletion mutants with unique sequence distributions, including intrinsically disordered regions (IDRs) and aggregation-prone regions, were constructed based on structural predictions. The overexpression of Nst1 deletion mutants lacking the aggregation-prone domain (APD) significantly inhibited self-condensation, implicating APD as an oligomerizing domain promoting self-condensation. Remarkably, cells overexpressing the Nst1 deletion mutant of the polyampholyte domain (PD) in the IDR region (Nst1_∆PD) rarely accumulate endogenous enhanced green fluorescent protein (EGFP)-tagged Dcp2. However, Nst1_∆PD formed self-condensates, suggesting that Nst1 requires PD to interact with Dcp2, regardless of its self-condensation. In Nst1_∆PD-overexpressing cells treated with cycloheximide (CHX), Dcp2, Xrn1, Dhh1, and Edc3 had significantly diminished condensation compared to those in CHX-treated Nst1-overexpressing cells. These observations suggest that the PD of the IDR in Nst1 functions as a hub domain interacting with other PB components.

Aralia and Panax , two neighboring medicinal plant genera, underwent diverse genomic evolution, including genome expansion and polyploidization. Their variable genome sizes, ploidy levels, and metabolite compositions make these genera valuable genomic resources for elucidating genome evolution. However, the lack of genomic data for the Aralia genus has hindered the full exploration of genomic features and evolution in this genus. Here, we assembled a high-quality chromosome-level genome of Aralia cordata with a length of 1.06 Gbp for 24 chromosomes. Candidate gene mining suggested that the gene loss and tandem gene duplication might be associated with the species-specific secondary metabolite compositions. Comprehensive genomic analyses with related species revealed their divergence history. Ancestral karyotype reconstruction suggested the modern chromosome evolution scenario of Araliaceae. Despite being tetraploid, A. cordata had a comparable genome size to the diploid A. elata , which has species-specific LTR expansions. We also inspected the distribution of the Araliaceae family-wide common 160 bp centromeric tandem repeat (TR160). The TR160s were identified in each chromosome of the Aralia and Eleutherococcus genera but not significantly in the Panax genus. The genomic analyses in this study provided valuable insight into chromosome evolution, polyploidization, and secondary metabolite diversification in the Araliaceae family.