Cutin and suberin are hydrophobic lipid biopolyester components of the cell walls of specialized plant tissue and cell-types, where they facilitate adaptation to terrestrial habitats. Many steps in ...their biosynthetic pathways have been characterized, but the basis of their spatial deposition and precursor trafficking is not well understood. Members of the GDSL lipase/esterase family catalyze cutin polymerization, and candidate proteins have been proposed to mediate interactions between cutin or suberin and other wall components. Comparative genomic studies of charophyte algae and early diverging land plants, combined with knowledge of the biosynthesis, trafficking and assembly mechanisms, suggests an origin for the capacity to secrete waxes, as well as aliphatic and phenolic compounds before the first colonization of true terrestrial habitats.
Assembly of tomato fruit cuticles Philippe, Glenn; Geneix, Nathalie; Petit, Johann ...
The New phytologist,
20/May , Letnik:
226, Številka:
3
Journal Article
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• The cuticle is an essential and ubiquitous biological polymer composite covering aerial plant organs, whose structural component is the cutin polyester entangled with cell wall polysaccharides. The ...nature of the cutin-embedded polysaccharides (CEPs) and their association with cutin polyester are still unresolved
• Using tomato fruit as a model, chemical and enzymatic pretreatments combined with biochemical and biophysical methods were developed to compare the fine structure of CEPs with that of the noncutinized polysaccharides (NCPs). In addition, we used tomato fruits from cutin-deficient transgenic lines cus1 (cutin synthase 1) to study the impact of cutin polymerization on the fine structure of CEPs.
• Cutin-embedded polysaccharides exhibit specific structural features including a high degree of esterification (i.e. methylation and acetylation), a low ramification of rhamnogalacturonan (RGI), and a high crystallinity of cellulose. In addition to decreasing cutin deposition and polymerization, cus1 silencing induced a specific modification of CEPs, especially on pectin content, while NCPs were not affected.
• This new evidence of the structural specificities of CEPs and of the cross-talk between cutin polymerization and polysaccharides provides new hypotheses concerning the formation of these complex lipopolysaccharide edifices.
Hemp (Cannabis sativa L.) is an emerging dioecious crop grown primarily for grain, fiber, and cannabinoids. There is good evidence for medicinal benefits of the most abundant cannabinoid in hemp, ...cannabidiol (CBD). For CBD production, female plants producing CBD but not tetrahydrocannabinol (THC) are desired. We developed and validated high‐throughput PACE (PCR Allele Competitive Extension) assays for C. sativa plant sex and cannabinoid chemotype. The sex assay was validated across a wide range of germplasm and resolved male plants from female and monoecious plants. The cannabinoid chemotype assay revealed segregation in hemp populations, and resolved plants producing predominantly THC, predominantly CBD, and roughly equal amounts of THC and CBD. Cultivar populations that were thought to be stabilized for CBD production were found to be segregating phenotypically and genotypically. Many plants predominantly producing CBD accumulated more than the current US legal limit of 0.3% THC by dry weight. These assays and data provide potentially useful tools for breeding and early selection of hemp.
The largest market for hemp in the US today is for cannabidiol (CBD). For CBD production, growers desire female plants producing minimal tetrahydrocannabinol (THC). We developed and validated high‐throughput molecular assays to distinguish male from female plants, as well as the cannabinoid chemotype (mostly THC, about equal THC and CBD, or mostly CBD). We found that in all three groups there was the potential to exceed the US legal limit of 0.3% THC, and that there was little effect of environment or cultivar per se on CBD:THC ratio. These assays and data will be useful in hemp breeding and production.
Hemp (Cannabis sativa) is a burgeoning crop, but research‐based information about genetic and environmental effects of cannabinoid production is limited and will be essential for expanded ...cultivation. There are limited data available about the effect of environmental stressors on cannabinoid content, particularly for tetrahydrocannabinol (THC) in high‐cannabidiol (CBD) hemp. To address this, five stress treatments were applied in a replicated field trial with three high‐CBD hemp cultivars and cannabinoid content was assayed over a 3‐week time‐course spanning floral maturation. Cannabinoid production in terminal inflorescence shoot tip samples of three cultivars was measured under stress imposed by flooding, ethephon, powdery mildew, herbicide, and physical wounding in a split plot design. The treatments had limited effects on cannabinoid levels, with the exception of herbicide treatment which resulted in decreased cannabinoid content. Notably, there was no evidence that any of these stresses caused THC concentration or the ratio of THC to CBD to increase at harvest.
Hemp (Cannabis sativa) is widely grown for cannabidiol (CBD) production, and some sources suggest that environmental stress causes unwanted “spikes” in tetrahydrocannabinol (THC). To test this theory, we applied various stresses to three hemp cultivars and looked at CBD and THC production. These stresses included powdery mildew, ethephon, flooding, herbicide, and physical wounding. We found that compared to a control, the only significant difference in CBD or THC was a decrease in the herbicide treated plants at harvest, with no difference in the CBD:THC ratio for any treatment. This suggests that environmental stress is not a factor in THC “spikes”.
Given the dramatic rise in high‐cannabinoid hemp (Cannabis sativa L.) production in the last decade, there is an increasingly urgent need to characterize available germplasm and develop knowledge to ...accelerate the breeding of uniform and stable cultivars. Despite persistent cultivation of hemp cultivars for grain and or fiber around the world, the diversity and genetic underpinning of key traits for breeding and cultivation are poorly understood. For 30 high‐cannabidiol hemp cultivars replicated on two field sites, we sought to evaluate yield, agronomic performance, and disease resistance while also conducting a detailed study of cannabinoid accumulation over the course of floral maturation. We observed significant variation in both within and among cultivars. During the growing season, the plants clustered into five groups by growth rate and varied in flowering time from photoperiod insensitive to photoperiod sensitive with very short critical photoperiods. Based on the observed ratio of total potential cannabidiol (CBD) to total potential tetrahydrocannabinol (THC), there was segregation for cannabinoid chemotype in some seeded cultivar populations. Analysis of cannabichromene (CBC) production revealed that some cultivars had a discretely lower CBD:CBC ratio than the others. There was a continuous range of powdery mildew severity by cultivar, with one that had little to no observed powdery mildew suggesting it might have genetic resistance. Biomass production at harvest was strongly influenced by location and cultivar, and there was variation by cultivar in the relative cannabinoid production in shoot tip samples compared with whole plant samples. While our results provide preliminary guidance regarding relative performance of current cultivars, our analyses indicate a need for additional hemp breeding to provide stable, uniform, and legally compliant cultivars with improved disease resistance and flowering times optimized for the latitudes of different growing locations.
There is an increasingly urgent need to evaluate hemp cultivars, especially those selected for cannabinoid production, and develop knowledge to accelerate the breeding of uniform and stable cultivars. This paper describes extensive characterization of 30 high‐cannabinoid hemp cultivars replicated on two sites. We describe variation for growth, flowering time, and cannabinoid production that will inform breeding programs and cultivar selection.
Cuticle function is closely related to the structure of the cutin polymer. However, the structure and formation of this hydrophobic polyester of glycerol and hydroxy/epoxy fatty acids has not been ...fully resolved. An apoplastic GDSL-lipase known as CUTIN SYNTHASE1 (CUS1) is required for cutin deposition in tomato (Solanum lycopersicum) fruit exocarp. In vitro, CUS1 catalyzes the self-transesterification of 2-monoacylglycerol of 9(10),16-dihydroxyhexadecanoic acid, the major tomato cutin monomer. This reaction releases glycerol and leads to the formation of oligomers with the secondary hydroxyl group remaining nonesterified. To check this mechanism in planta, a benzyl etherification of nonesterified hydroxyl groups of glycerol and hydroxy fatty acids was performed within cutin. Remarkably, in addition to a significant decrease in cutin deposition, mid-chain hydroxyl esterification of the dihydroxyhexadecanoic acid was affected in tomato RNA interference and ethyl methanesulfonate-cus1 mutants. Furthermore, in these mutants, the esterification of both sn-1,3 and sn-2 positions of glycerol was impacted, and their cutin contained a higher molar glycerol-to-dihydroxyhexadecanoic acid ratio. Therefore, in planta, CUS1 can catalyze the esterification of both primary and secondary alcohol groups of cutin monomers, and another enzymatic or nonenzymatic mechanism of polymerization may coexist with CUS1-catalyzed polymerization. This mechanism is poorly efficient with secondary alcohol groups and produces polyesters with lower molecular size. Confocal Raman imaging of benzyl etherified cutins showed that the polymerization is heterogenous at the fruit surface. Finally, by comparing tomato mutants either affected or not in cutin polymerization, we concluded that the level of cutin cross-linking had no significant impact on water permeance.
Cuticles are specialized cell wall structures that form at the surface of terrestrial plant organs. They are largely comprised lipidic compounds and are deposited in the apoplast, external to the ...polysaccharide-rich primary wall, creating a barrier to diffusion of water and solutes, as well as to environmental factors. The predominant cuticle component is cutin, a polyester that is assembled as a complex matrix, within and on the surface of which aliphatic and aromatic wax molecules accumulate, further modifying its properties. To reach the point of cuticle assembly the different acyl lipid-containing components are first exported from the cell across the plasma membrane and then traffic across the polysaccharide wall. The export of cutin precursors and waxes from the cell is known to involve plasma membrane-localized ATP-binding cassette (ABC) transporters; however, other secretion mechanisms may also contribute. Indeed, extracellular vesiculo-tubular structures have recently been reported in
(Arabidopsis) to be associated with the deposition of suberin, a polyester that is structurally closely related to cutin. Intriguingly, similar membranous structures have been observed in leaves and petals of Arabidopsis, although in lower numbers, but no close association with cutin formation has been identified. The possibility of multiple export mechanisms for cuticular components acting in parallel will be discussed, together with proposals for how cuticle precursors may traverse the polysaccharide cell wall before their assimilation into the cuticle macromolecular architecture.
The cutin polymers of different fruit cuticles (tomato, apple, nectarine) were examined using matrix‐assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) after in situ release ...of the lipid monomers by alkaline hydrolysis. The mass spectra were acquired from each coordinate with a lateral spatial resolution of approximately 100 μm. Specific monomers were released at their original location in the tissue, suggesting that post‐hydrolysis diffusion can be neglected. Relative quantification of the species was achieved by introducing an internal standard, and the collection of data was subjected to non‐supervised and supervised statistical treatments. The molecular images obtained showed a specific distribution of ions that could unambiguously be ascribed to cutinized and suberized regions observed at the surface of fruit cuticles, thus demonstrating that the method is able to probe some structural changes that affect hydrophobic cuticle polymers. Subsequent chemical assignment of the differentiating ions was performed, and all of these ions could be matched to cutin and suberin molecular markers. Therefore, this MALDI‐MSI procedure provides a powerful tool for probing the surface heterogeneity of plant lipid polymers. This method should facilitate rapid investigation of the relationships between cuticle phenotypes and the structure of cutin within a large population of mutants.
Cannabis sativa is cultivated for multiple uses including the production of cannabinoids. In developing improved production systems for high‐cannabinoid cultivars, scientists and cultivators must ...consider the optimization of complex and interacting sets of morphological, phenological, and biochemical traits, which have historically been shaped by natural and anthropogenic selection. Determining factors that modulate cannabinoid variation within and among genotypes is fundamental to developing efficient production systems and understanding the ecological significance of cannabinoids. Thirty‐two high‐cannabinoid hemp cultivars were characterized for traits including flowering date and shoot‐tip cannabinoid concentration. Additionally, a set of plant architecture traits, as well as wet, dry, and stripped inflorescence biomass were measured at harvest. One plant per plot was partitioned post‐harvest to quantify intra‐plant variation in inflorescence biomass production and cannabinoid concentration. Some cultivars showed intra‐plant variation in cannabinoid concentration, while many had a consistent concentration regardless of canopy position. There was both intra‐ and inter‐cultivar variation in architecture that correlated with intra‐plant distribution of inflorescence biomass, and concentration of cannabinoids sampled from various positions within a plant. These relationships among morphological and biochemical traits will inform future decisions by cultivators, regulators, and plant breeders.
The evolutionary features and molecular innovations that enabled plants to first colonize land are not well understood. Here, insights are provided through our report of the genome sequence of the ...unicellular alga Penium margaritaceum, a member of the Zygnematophyceae, the sister lineage to land plants. The genome has a high proportion of repeat sequences that are associated with massive segmental gene duplications, likely facilitating neofunctionalization. Compared with representatives of earlier diverging algal lineages, P. margaritaceum has expanded repertoires of gene families, signaling networks, and adaptive responses that highlight the evolutionary trajectory toward terrestrialization. These encompass a broad range of physiological processes and protective cellular features, such as flavonoid compounds and large families of modifying enzymes involved in cell wall biosynthesis, assembly, and remodeling. Transcriptome profiling further elucidated adaptations, responses, and selective pressures associated with the semi-terrestrial ecosystems of P. margaritaceum, where a simple body plan would be an advantage.
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•The genome and responses of a charophyte alga uncover terrestrialization mechanisms•Paradoxical presence of protective UV-absorbing flavonoid pigments•Evolutionary origins of plant hydrophobic polymer classes that limit water loss•Expanded repertoire of genes for polysaccharide cell wall biosynthesis and remodeling
The genome sequence of Penium margaritaceum reveals that this freshwater algal species and member of the sister lineage to land plants contains several advantageous features for life on land, including an expanded repertoire of genes for cell wall biosynthesis, traces of pathways to form hydrophobic polymer classes that limit water loss, and flavonoid pigments that protect against UV radiation.
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