Analyses of the oil content, fatty acid composition, and antioxidant activity in seeds of Thlaspi arvense L. from different provenances and correlations with environmental factors

Background Pennycress (Thlaspi arvense L.) is an annual herbaceous plant of the Cruciferae family that has attracted attention as an oil crop and interseeded cover crop. We collected seeds of pennycress from five provenances in Northeast China, compared their characteristics, i.e. oil content, fatty acid composition, physical, chemical and antioxidant properties, their correlations with environmental factors were also analysed. Results There were significant differences in the seed characteristics, oil content, quality indicators and composition among different provenances (P < 0.05). The 1000-seed weight ranged from 0.80 to 1.03 g; seed oil content from 28.89 to 42.57%; iodine from 79.19 to 99.09; saponification value from 186.51 to 199.60; peroxide value from 0.07 to 10.60; and acid value from 0.97 to 13.02. The range of seed oil colours were 66.53–78.78 (L*), 4.51–10.29 (a*), and 105.68–121.35 (b*). Erucic acid (C22:1) was the fatty acids with the highest content in pennycress seed oils (31.12–35.31%), followed by linoleic acid (C18:2 16.92–18.95%) and α-linolenic acid (C18:3 14.05–15.34%). The fatty acid 8,11,14-eicosatrienoic acid (C20:3) was detected for the first time in seed oils from Beian city, Panshi city and Kedong county, with contents of 1.13%, 0.84% and 1.03%, respectively. We compare and report for the first time on the radical-scavenging activity of the seed oils of pennycress. The EC50 values of the DPPH radical-scavenging activity and ABTS+ radical-scavenging activity of the seed oils from different provenances were 8.65–19.21 mg/mL and 6.82–10.61 mg/mL, respectively. The ferric ion reduction antioxidant capacity (FRAP) ranged from 0.11 to 0.30 mmol Fe2+/g, which is equivalent to 4 mg/mL FeSO4 of pennycress seed oils. Conclusions There was a significant correlation between seed characteristics and changes in geographical factors. With increasing longitude, the thickness of seeds, 1000-seed weight, and seed oil content increased, while the acid and peroxide values of the seed oil decreased. As the latitude increased, the 1000-seed weight and seed oil content increased, while the seed oil peroxide value decreased. Furthermore, mean annual temperature and annual rainfall are the two key environmental factors affecting the quality of pennycress. Graphical Abstract

A cultivar of brown mustard Alisa

Brown mustard is one of the valuable oil crops which allows increasing the production of edible vegetable oil. In the conditions of insufficient moisture in the Rostov region, new cultivars of brown mustard are being developed, which combine yield, early maturity with high product quality and are resistant to stress factors. A new cultivar of brown mustard Alisa was bred by the method of individual selection from the hybrid population G-2384 (G-2319 × 50041). According to the results of competitive trials for 2017–2019, the cultivar Alisa exceeded the standard cultivar Lux by seed yield by 0.31 t per ha, seed oil content – by 0.8%. The brown mustard cultivar Alisa is characterized by a lower plant height, increased tolerance to major pathogens, and greater resistance to lodging. Plants are well uniformed in height, blooming and maturity. The cultivar was registered in 2020 in the State Register of breeding achievements approved for production. It is recommended for cultivation for grain in all regions of the Russian Federation.

An integrated omics analysis reveals the gene expression profiles of rapeseed, castor bean, and maize for seed oil biosynthesis

Background Seed storage lipids are valuable for human diet and for the sustainable development of mankind. In recent decades, many lipid metabolism genes and pathways have been identified, but the molecular mechanisms that underlie species differences in seed oil biosynthesis are not fully understood. Results To investigate the molecular mechanisms of seed oil accumulation in different species, we performed comparative genome and transcriptome analyses of rapeseed and castor bean, which have high seed oil contents, and maize, which has a low seed oil content. The results uncovered the molecular mechanism of the low and high seed oil content in maize and castor bean, respectively. Transcriptome analyses showed that more than 61% of the lipid- and carbohydrate-related genes were regulated in rapeseed and castor bean, but only 20.1% of the lipid-related genes and 22.5% of the carbohydrate-related genes were regulated in maize. Compared to rapeseed and castor bean, fewer lipid biosynthesis genes but more lipid metabolism genes were regulated in the maize embryo. More importantly, most maize genes encoding lipid-related transcription factors, triacylglycerol (TAG) biosynthetic enzymes, pentose phosphate pathway (PPP) and Calvin Cycle proteins were not regulated during seed oil synthesis, despite the presence of many homologs in the maize genome. These results revealed the molecular underpinnings of the low seed oil content in maize. In castor bean, we observed differential regulation of vital oil biosynthetic enzymes and extremely high expression levels of oil biosynthetic genes, which were consistent with the rapid accumulation of oil in castor bean developing seeds. Conclusions Compared to oil seed (rapeseed and castor bean), less oil biosynthetic genes were regulated during the seed development in non-oil seed (maize). These results shed light on molecular mechanisms of lipid biosynthesis in rapeseed, castor bean, and maize. They can provide information on key target genes that may be useful for future experimental manipulation of oil production in oilseed crops.

Genome-wide identification and analysis of Oleosin gene family in four cotton species and its involvement in oil accumulation and germination

Background Cotton is not only a major textile fiber crop but also a vital oilseed, industrial, and forage crop. Oleosins are the structural proteins of oil bodies, influencing their size and the oil content in seeds. In addition, the degradation of oleosins is involved in the mobilization of lipid and oil bodies during seed germination. However, comprehensive identification and the systematic analysis of the Oleosin gene (OLEOs) family have not been conducted in cotton. Results An in-depth analysis has enabled us to identify 25 and 24 OLEOs in tetraploid cotton species G. hirsutum and G. barbadense, respectively, while 12 and 13 OLEOs were identified in diploid species G. arboreum and G. raimondii, respectively. The 74 OLEOs were further clustered into three lineages according to the phylogenetic tree. Synteny analysis revealed that most of the OLEOs were conserved and that WGD or segmental duplications might drive their expansion. The transmembrane helices in GhOLEO proteins were predicted, and three transmembrane models were summarized, in which two were newly proposed. A total of 24 candidate miRNAs targeting GhOLEOs were predicted. Three highly expressed oil-related OLEOs, GH_A07G0501 (SL), GH_D10G0941 (SH), and GH_D01G1686 (U), were cloned, and their subcellular localization and function were analyzed. Their overexpression in Arabidopsis increased seed oil content and decreased seed germination rates. Conclusion We identified OLEO gene family in four cotton species and performed comparative analyses of their relationships, conserved structure, synteny, and gene duplication. The subcellular localization and function of three highly expressed oil-related OLEOs were detected. These results lay the foundation for further functional characterization of OLEOs and improving seed oil content.

Integrated Transcriptomic and Bioinformatics Analyses Reveal the Molecular Mechanisms for the Differences in Seed Oil and Starch Content Between Glycine max and Cicer arietinum

The seed oil and starch content of soybean are significantly different from that of chickpea. However, there are limited studies on its molecular mechanisms. To address this issue, we conducted integrated transcriptomic and bioinformatics analyses for species-specific genes and acyl-lipid-, starch-, and carbon metabolism-related genes. Among seven expressional patterns of soybean-specific genes, four were highly expressed at the middle- and late oil accumulation stages; these genes significantly enriched fatty acid synthesis and carbon metabolism, and along with common acetyl CoA carboxylase (ACCase) highly expressed at soybean middle seed development stage, common starch-degrading enzyme beta-amylase-5 (BAM5) was highly expressed at soybean early seed development stage and oil synthesis-related genes ACCase, KAS, KAR, ACP, and long-chain acyl-CoA synthetase (LACS) were co-expressed with WRI1, which may result in high seed oil content and low seed starch content in soybean. The common ADP-glucose pyrophosphorylase (AGPase) was highly expressed at chickpea middle seed development stage, along with more starch biosynthesis genes co-expressed with four-transcription-factor homologous genes in chickpea than in soybean, and the common WRI1 was not co-expressed with oil synthesis genes in chickpea, which may result in high seed starch content and low seed oil content in chickpea. The above results may be used to improve chickpea seed oil content in two ways. One is to edit CaWRI1 to co-express with oil synthesis-related genes, which may increase carbon metabolites flowing to oil synthesis, and another is to increase the expression levels of miRNA159 and miRNA319 to inhibit the expression of MYB33, which may downregulate starch synthesis-related genes, making more carbon metabolites flow into oil synthesis. Our study will provide a basis for future breeding efforts to increase the oil content of chickpea seeds.

Effects of Genotype and Climatic Conditions on the Oil Content and Its Fatty Acids Composition of Carthamus tinctorius L. Seeds

Safflower seeds provide an oil rich in mono and polyunsaturated fatty acids. Its adaptation to drought and high temperatures makes it an alternative for the development of oleaginous crops in semi-arid areas. This study examines the oil content and the chemical composition of seed oil from three safflower accessions (Gila, Halab, Touggourt) cultivated over three years (2015, 2016, and 2017) in a semi-arid area in Tiaret (West of Algeria). Under these semi-arid conditions, characterized by low rainfall and high temperatures, seed oil content remained relatively high and was composed mainly of unsaturated fatty acids, with their ratio to saturated fatty acids reaching an average value of 9. Seed oil content varies between 22.8% and 28.4% among the genotypes and throughout the three years. The extracted oil consists essentially of unsaturated fatty acids, linoleic and oleic acids, poly and monounsaturated, respectively. Their contents over the three years vary between 75% and 79.3% for linoleic acid and between 10.2% and 14.7% for oleic acid. The saturated fatty acids content of the oil reached a maximum value of 9%. They consist mainly of palmitic acid, of which the average genotypic content varies between 6.6% and 7.15% depending on all grown years. The results obtained may assist in better understanding the response of cultivars under rainfed conditions and could be helpful for breeders with regards to introduction into selection programs.

Integument-Specific Transcriptional Regulation in the Mid-Stage of Flax Seed Development Influences the Release of Mucilage and the Seed Oil Content

Flax (Linum usitatissimum L.) seed oil, which accumulates in the embryo, and mucilage, which is synthesized in the seed coat, are of great economic importance for food, pharmaceutical as well as chemical industries. Theories on the link between oil and mucilage production in seeds consist in the spatio-temporal competition of both compounds for photosynthates during the very early stages of seed development. In this study, we demonstrate a positive relationship between seed oil production and seed coat mucilage extrusion in the agronomic model, flax. Three recombinant inbred lines were selected for low, medium and high mucilage and seed oil contents. Metabolite and transcript profiling (1H NMR and DNA oligo-microarrays) was performed on the seeds during seed development. These analyses showed main changes in the seed coat transcriptome during the mid-phase of seed development (25 Days Post-Anthesis), once the mucilage biosynthesis and modification processes are thought to be finished. These transcriptome changes comprised genes that are putatively involved in mucilage chemical modification and oil synthesis, as well as gibberellic acid (GA) metabolism. The results of this integrative biology approach suggest that transcriptional regulations of seed oil and fatty acid (FA) metabolism could occur in the seed coat during the mid-stage of seed development, once the seed coat carbon supplies have been used for mucilage biosynthesis and mechanochemical properties of the mucilage secretory cells.

The Brassica napus fatty acid exporter FAX1-1 contributes to biological yield, seed oil content, and oil quality

Background In the oilseed crop Brassica napus (rapeseed), various metabolic processes influence seed oil content, oil quality, and biological yield. However, the role of plastid membrane proteins in these traits has not been explored. Results Our genome-wide association study (GWAS) of 520 B. napus accessions identified the chloroplast membrane protein-localized FATTY ACID EXPORTER 1-1 (FAX1-1) as a candidate associated with biological yield. Seed transcript levels of BnaFAX1-1 were higher in a cultivar with high seed oil content relative to a low-oil cultivar. BnaFAX1-1 was localized to the plastid envelope. When expressed in Arabidopsis thaliana, BnaFAX1-1 enhanced biological yield (total plant dry matter), seed yield and seed oil content per plant. Likewise, in the field, B. napus BnaFAX1-1 overexpression lines (BnaFAX1-1-OE) displayed significantly enhanced biological yield, seed yield, and seed oil content compared with the wild type. BnaFAX1-1 overexpression also up-regulated gibberellic acid 4 (GA4) biosynthesis, which may contribute to biological yield improvement. Furthermore, oleic acid (C18:1) significantly increased in BnaFAX1-1 overexpression seeds. Conclusion Our results indicated that the putative fatty acid exporter BnaFAX1-1 may simultaneously improve seed oil content, oil quality and biological yield in B. napus, providing new approaches for future molecular breeding.

INTEGUMENT-SPECIFIC TRANSCRIPTIONAL REGULATION IN THE MID-STAGE OF FLAX SEED DEVELOPMENT INFLUENCES THE RELEASE OF MUCILAGE AND THE SEED OIL CONTENT

ABSTRACTFlax (Linum usitatissimum L.) seed oil, which accumulates in the embryo, and mucilage, which is synthesized in the seed coat, are of great economic importance for food, pharmaceutical as well as chemical industries. Theories on the link between oil and mucilage production in seeds consist in the spatio-temporal competition of both compounds for photosynthates during the very early stages of seed development. In this study, we demonstrate a positive relationship between seed oil production and seed coat mucilage extrusion in the agronomic model, flax. Three recombinant inbred lines were selected for low, medium and high mucilage and seed oil contents. Metabolite and transcript profiling (1H NMR and DNA oligo-microarrays) was performed on the seeds during seed development. These analyses showed main changes in the seed coat transcriptome during the mid-phase of seed development (25 Days Post-Anthesis), once the mucilage biosynthesis and modification processes are thought to be finished. These transcriptome changes comprised genes that are putatively involved in mucilage chemical modification and oil synthesis, as well as gibberellic acid (GA) metabolism. The results of these integrative biology approach, suggest that transcriptional regulations of seed oil and fatty acid (FA) metabolism could occur in the seed coat during the mid-stage of seed development, once the seed coat carbon supplies have been used for mucilage biosynthesis and mechanochemical properties of the mucilage secretory cells.