Arabidopsis root lipid droplets are hubs for membrane homeostasis under heat stress, and triterpenoid synthesis and storage.
Authors: Scholz, P., Dabisch, J., Clews, A. C., Niemeyer, P. W., Vilchez, A. C., Lim, M. S. S., Sun, S., Hembach, L., Dreier, F., Blersch, K., Preuss, L., Bonin, M., Lesch, E., Iwai, Y., Shimada, T., Eirich, J., Finkemeier, I., Gutbrod, K., Doermann, P., Wang, Y., Mullen, R. T., Ischebeck, T.
The study examined how heat stress alters lipid droplet (LD) number and composition in Arabidopsis thaliana roots, revealing degradation of membrane lipids and accumulation of TAGs and LDs. Proteomic and lipidomic analyses of LDs from a specific Arabidopsis mutant identified novel LD-associated proteins, including triterpene biosynthetic enzymes, whose substrates and products also accumulate in LDs, indicating LDs function as both sinks and sources during stress‑induced membrane remodeling and specialized metabolism.
The study investigates the role of the Arabidopsis transcription factor AtMYB93 in sulfur (S) signaling and root development, revealing that AtMYB93 mutants exhibit altered expression of S transport and metabolism genes and increased shoot S levels, while tomato plants overexpressing SlMYB93 show reduced shoot S. Transcriptomic profiling, elemental analysis, and promoter activity assays indicate that AtMYB93 contributes to root responses to S deprivation, though functional redundancy masks clear phenotypic effects on lateral and adventitious root formation.
The study investigates the Arabidopsis ribosomal protein RPS6A and its role in auxin‑related root growth, revealing that rps6a mutants display shortened primary roots, fewer lateral roots, and defective vasculature that are not rescued by exogenous auxin. Cell biological observations and global transcriptome profiling show weakened auxin signaling and reduced levels of PIN auxin transporters in the mutant, indicating a non‑canonical function of the ribosomal subunit in auxin pathways.
The study demonstrates that knock‑down of CDP‑DAG synthase (CDS) genes in Arabidopsis thaliana enhances resistance to multiple pathogens but incurs a growth penalty, associated with elevated reactive oxygen species and MAPK activation. Integrated lipidomics, transcriptomics, and metabolomics reveal PA accumulation in cds mutants, which triggers JA and SA signaling and increases defense‑related metabolites such as serotonin.