Kosma, D. K. | bioRxiv Science

bioRxiv2025

Dehydration promotes intracellular lipid synthesis and accumulation

Lipids can be considered a water reservoir used to offset dehydration stress as their oxidation by the mitochondria generates water. However, whether dehydration and the ensuing hypertonic stress directly regulate lipid synthesis is unknown. We found that hypertonic stress decreases cellular oxygen consumption, increases intracellular lipid synthesis, and favors glutamine oxidation as a carbon precursor for lipid synthesis via remodeling mitochondrial metabolism. These findings provide a mechanism whereby cellular dehydration leads to intracellular lipid accumulation, functionally linking water availability to lipid storage.

physiology↗

bioRxiv2022

The last missing piece of the Triangle of U: the evolution of the tetraploid Brassica carinata genome

Ethiopian mustard (Brassica carinata) is an ancient crop with significant potential for expanded cultivation as a biodiesel feedstock. The remarkable stress resilience of B. carinata and desirable seed fatty acid profile addresses the ongoing food vs. fuel debate as the crop is productive on marginal lands otherwise not suitable for even closely related species. B. carinata is one of six key Brassica spp. that share three major genomes: three diploid species (AA, BB, CC) that spontaneously hybridized in a pairwise manner, forming three allotetraploid species (AABB, AACC, and BBCC). Each of these genomes has been researched extensively, except for that of B. carinata. In the present study, we report a high-quality, 1.31 Gbp genome with 156.9-fold sequencing coverage for B. carinata var. Gomenzer, completing and confirming the classic Triangle of U, a theory of the evolutionary relationships among these six species that arose almost a century ago. Our assembly provides insights into the genomic features that give rise to B. carinatas superior agronomic traits for developing more climate-resilient Brassica crops with excellent oil production. Notably, we identified an expansion of transcription factor networks and agronomically-important gene families. Completing the Triangle of U comparative genomics platform allowed us to examine the dynamics of polyploid evolution and the role of subgenome dominance in domestication and agronomical improvement.

genetics↗

bioRxiv2020

Extracellular lipids of Camelina sativa: Characterization of cutin and suberin reveals typical polyester monomers and novel functionalized dicarboxylic fatty acids

Camelina sativa is relatively drought tolerant and requires less fertilizer than other oilseed crops. Various lipid- and phenolic-based extracellular barriers of plants help to protect them against biotic and abiotic stresses. These barriers, which consist of solvent-insoluble polymeric frameworks and solvent-extractable waxes, include the cuticle of aerial plant surfaces and suberized cell walls found, for example, in periderms and seed coat. Cutin, the polymeric matrix of the cuticle, and the aliphatic domain of suberin are fatty acid- and glycerol-based polyesters. These polyesters were investigated by base-catalyzed transesterification of C. sativa aerial and underground delipidated tissues followed by gas chromatographic analysis of the released monomer mixtures. Seed coat and root suberin had similar compositions, with 18-hydroxyoctadecenoic and 1,18-octadecenedioic fatty acids being the dominant species. Root suberin presented a typical lamellar ultrastructure, but seed coats showed almost imperceptible, faint dark bands. Leaf and stem lipid polyesters were composed of fatty acids (FA), dicarboxylic acids (DCA), {omega}-hydroxy fatty acids (OHFA) and hydroxycinnamic acid derivatives (HCA). Dihydroxypalmitate (DHP) and caffeic acid were the major constituents of leaf cutin, whereas stem cutin presented similar molar proportions in several monomers across the four classes. Unlike the leaf cuticle, the C. sativa stem cuticle presented lamellar structure by transmission electron microscopy. Flower cutin was dominated by DHP and did not contain aromatics. We found striking differences between the lipid polyester monomer compositions of aerial tissues of C. sativa and that of its close relatives Arabidopsis thaliana and Brassica napus. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=96 SRC="FIGDIR/small/163436v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@1d9f07eorg.highwire.dtl.DTLVardef@13c1ca4org.highwire.dtl.DTLVardef@17c6f50org.highwire.dtl.DTLVardef@7013e7_HPS_FORMAT_FIGEXP M_FIG C_FIG Camelina sativa leaf and stem cutin is dominated by 16:0 dihydroxy fatty acid and aromatics, with dicarboxylic fatty acids representing 20-30 % of the monomers. Suberin of root and seed coat is largely composed of 18:1 dicarboxylic and {omega}-hydroxy fatty acids. Highlight bullet pointsO_LICamelina sativa is an oil crop tolerant to biotic and abiotic stresses C_LIO_LIExtracellular lipid polyesters may in part confer these attributes C_LIO_LIDihydroxypalmitate and caffeic acid were major components of C. sativa leaf cutin C_LIO_LIFlower cutin lacked aromatics and contained monomers not previously reported C_LIO_LIRoot and seed coat suberin was dominated by 18:1 {omega}-hydroxy and dicarboxylic fatty acids C_LIO_LIC18 monounsaturated photo-oxidation products were found in leaf cutin and suberin C_LI

plant biology↗