Overexpression of Soybean GmWRI1a Stably Increases the Seed Oil Content in Soybean

The drought-responsive wheat AP2/ERF transcription factor TaRAP2-13L and its interacting protein TaWRKY10 enhance drought tolerance in transgenic Arabidopsis and wheat (Triticum aestivum L.)

AP2/ERF transcription factors (TFs) are one of the largest TF families involved in plant growth, development, and stress responses. Drought, a major abiotic stress, severely impacts wheat yield and quality. In this study, we identified a wheat AP2/ERF gene, TaRAP2-13L, which was significantly upregulated in response to drought stress. Subcellular localization and transcriptional activity assays indicated that TaRAP2-13L localizes in the nucleus but lacks transcriptional activity. Overexpression of TaRAP2-13L in Arabidopsis enhanced drought tolerance, while silencing TaRAP2-13L in wheat reduced drought tolerance by modulating the ABA signaling pathway and reactive oxygen species homeostasis. Through yeast two-hybrid screening, TaWRKY10 was identified as an interacting protein of TaRAP2-13L, and their interaction was further confirmed by bimolecular fluorescence complementation, luciferase complementation imaging assays, and GST pull-down assays. Functional analysis revealed that TaWRKY10 exhibited a similar role to TaRAP2-13L in drought response. Transcriptional regulation analysis showed that co-expression of TaRAP2-13L and TaWRKY10 complex significantly enhanced transcriptional activity, particularly under drought conditions induced by PEG6000. Moreover, dual-luciferase assays demonstrated that TaRAP2-13L and TaWRKY10 can activate the expression of TaSOD3-2A, TaSOD3-2D, TaGPX1-D, and TaNCED2-5B, with co-expression of both TFs enhancing this activation. Further assays revealed that TaRAP2-13L binds to the DRE motif, TaSOD3-2A, and TaSOD3-2D promoters, while TaWRKY10 binds to the W-box, and TaSOD3-2A promoter. These findings highlight a synergistic mechanism by which TaRAP2-13L and TaWRKY10 regulate drought tolerance, offering potential targets for improving drought tolerance in wheat through transgenic strategies.

Integrated analysis of lipid metabolism and differentially expressed genes reveal seed oil accumulation in field muskmelon

Field muskmelon (Cucumis melo L. var. agrestis Naud.), a novel oil crop, contains a high amount of lipids in seeds. However, the high-resolution profiles and dynamic regulation of its lipids remain largely unknown. This study identified the lipids and analyzed their dynamic changes using UHPLC-MS/MS. We identified 2533 lipid molecules in the seeds, including 7 categories and 47 sub-classes, with the higher proportions of glycerolipids (41.02 %) and glycerophospholipids (28.11 %). Moreover, the content of glycerolipids was the highest, particularly for triacylglycerol lipid molecules. Additionally, the expression patterns of differentially expressed genes (DEGs) showed a close correlation with lipid accumulation, especially within the plant hormone signaling pathway. Notably, the sufficient supply of 18:1-CoA, coupled with a high expression level of CmFAD2, contributed significantly to the high linoleic acid (68.56 %) content in field muskmelon seeds. Our findings offer insights that could enhance the comprehensive understanding of lipids in field muskmelon, and facilitate the breeding of field muskmelon.

The transcription factors GmVOZ1A and GmWRI1a synergistically regulate oil biosynthesis in soybean

Soybean (Glycine max [L.] Merr.) is a major oil-producing crop worldwide. Although several related proteins regulating soybean oil accumulation have been reported, little is known about the regulatory mechanisms. In this study, we characterized vascular plant one-zinc-finger 1A (GmVOZ1A) that interacts with WRINKLED 1a (GmWRI1a) using yeast 2-hybrid library screening. The GmVOZ1A-GmWRI1a interaction was further verified by protein-protein interaction assays in vivo and in vitro. GmVOZ1A enhanced the seed fatty acid and oil contents by regulating genes involved in lipid biosynthesis. Conversely, a loss-of-function mutation in GmVOZ1A resulted in a reduction in triacylglycerol (TAG) content in soybean. Protein-DNA interaction assays revealed that GmVOZ1A and GmWRI1a cooperate to upregulate the expression level of acyl-coenzyme A-binding protein 6a (GmACBP6a) and promote the accumulation of TAG. In addition, GmACBP6a overexpression promoted seed fatty acid and oil contents, as well as increased seed size and 100-seed weight. Taken together, these findings indicate that the transcription factor GmVOZ1A regulates soybean oil synthesis and cooperates with GmWRI1a to upregulate GmACBP6a expression and oil biosynthesis in soybean. The results lay a foundation for a comprehensive understanding of the regulatory mechanisms underlying soybean oil biosynthesis and will contribute to improving soybean oil production through molecular breeding approaches.

Endosperm-specific expressed transcription factor protein WRINKLED1-mediated oil accumulative mechanism in woody oil peony Paeonia ostii var. lishizhenii

Paeonia ostii var. lishizhenii exhibits superiority of high α-linolenic acid in seed oils, yet, the low yield highlights the importance of enhancing oil accumulation in seeds for edible oil production. The transcription factor protein WRINKLED1 (WRI1) plays crucial roles in modulating oil content in higher plants; however, its functional characterization remains elusive in P. ostii var. lishizhenii. Herein, based on a correlation analysis of transcription factor transcript levels, FA accumulation rates, and interaction assay of FA biosynthesis associated proteins, a WRI1 homologous gene (PoWRI1) that potentially regulated oil content in P. ostii var. lishizhenii seeds was screened. The PoWRI1 exhibited an endosperm-specific and development-depended expression pattern, encoding a nuclear-localized protein with transcriptional activation capability. Notably, overexpressing PoWRI1 upregulated certain key genes relevant to glycolysis, FA biosynthesis and desaturation, and improved seed development, oil body formation and oil accumulation in Arabidopsis seeds, resulting an enhancement of total seed oil weight by 9.47-18.77 %. The defective impacts on seed phenotypes were rescued through ectopic induction of PoWRI1 in wri1 mutants. Our findings highlight the pivotal role of PoWRI1 in controlling oil accumulation in P. ostii var. lishizhenii, offering bioengineering strategies to increase seed oil accumulation and enhance its potential for edible oil production.

Soybean Oil and Protein: Biosynthesis, Regulation and Strategies for Genetic Improvement

Soybean (Glycine max [L.] Merr.) is one of the world's most important sources of oil and vegetable protein. Much of the energy required for germination and early growth of soybean seeds is stored in fatty acids, mainly as triacylglycerols (TAGs), and the main seed storage proteins are β-conglycinin (7S) and glycinin (11S). Recent research advances have deepened our understanding of the biosynthetic pathways and transcriptional regulatory networks that control fatty acid and protein synthesis in organelles such as the plastid, ribosome and endoplasmic reticulum. Here, we review the composition and biosynthetic pathways of soybean oils and proteins, summarizing the key enzymes and transcription factors that have recently been shown to regulate oil and protein synthesis/metabolism. We then discuss the newest genomic strategies for manipulating these genes to increase the food value of soybeans, highlighting important priorities for future research and genetic improvement of this staple crop.

Formulation of a High-Quality Cold-Pressed Vegetable Oil (Virgin) Based on a Blend of Four Oilseeds

Vegetable oils are crucial for the human diet, providing energy and essential fatty acids. This study investigates the formulation of a high-quality cold-pressed vegetable oil blend from rapeseed, sunflower, sesame, and safflower, chosen for their agronomic benefits, cost-effectiveness, and reduced environmental impact. For the first time, this study is carried out in order to enhance the nutritional profile of these blend oils compared to commercial oils. The study's results showed that all formulated blend oils had higher total polyphenol and flavonoid content. Specifically, the blend of 1/2 rapeseed, 1/4 sunflower, 1/8 sesame, and 1/8 safflower had an oil yield ranging from 37 to 39% and was rich in total polyphenols (18 mg GAE/100 g), total flavonoids (2 mg/g), antioxidant activities (52%), oleic acid (46.4%), and saturated fatty acids (11%), with a balanced omega-6/omega-3 ratio (2.5). Consuming this blend oil offers a healthier choice rich in nutrients and natural antioxidants. This could open new market opportunities and cater to the growing demand for healthier oil options, especially since it is extracted without a refining process. Further research could focus on the sensory attributes and consumer acceptance of these blend oils to ensure market success, noting that sesame and sunflower involve agreeable pronounced aromas.

Tissue culture and Agrobacterium-mediated genetic transformation of the oil crop sunflower

Sunflower is one of the four major oil crops in the world. 'Zaoaidatou' (ZADT), the main variety of oil sunflower in the northwest of China, has a short growth cycle, high yield, and high resistance to abiotic stress. However, the ability to tolerate adervesity is limited. Therefore, in this study, we used the retention line of backbone parent ZADT as material to establish its tissue culture and genetic transformation system for new variety cultivating to enhance resistance and yields by molecular breeding. The combination of 0.05 mg/L IAA and 2 mg/L KT in MS was more suitable for direct induction of adventitious buds with cotyledon nodes and the addition of 0.9 mg/L IBA to MS was for adventitious rooting. On this basis, an efficient Agrobacterium tumefaciens-mediated genetic transformation system for ZADT was developed by the screening of kanamycin and optimization of transformation conditions. The rate of positive seedlings reached 8.0%, as determined by polymerase chain reaction (PCR), under the condition of 45 mg/L kanamycin, bacterial density of OD600 0.8, infection time of 30 min, and co-cultivation of three days. These efficient regeneration and genetic transformation platforms are very useful for accelerating the molecular breeding process on sunflower.

Natural variation in Fatty Acid 9 is a determinant of fatty acid and protein content

Soybean is one of the most economically important crops worldwide and an important source of unsaturated fatty acids and protein for the human diet. Consumer demand for healthy fats and oils is increasing, and the global demand for vegetable oil is expected to double by 2050. Identification of key genes that regulate seed fatty acid content can facilitate molecular breeding of high-quality soybean varieties with enhanced fatty acid profiles. Here, we analysed the genetic architecture underlying variations in soybean seed fatty acid content using 547 accessions, including mainly landraces and cultivars from northeastern China. Through fatty acid profiling, genome re-sequencing, population genomics analyses, and GWAS, we identified a SEIPIN homologue at the FA9 locus as an important contributor to seed fatty acid content. Transgenic and multiomics analyses confirmed that FA9 was a key regulator of seed fatty acid content with pleiotropic effects on seed protein and seed size. We identified two major FA9 haplotypes in 1295 resequenced soybean accessions and assessed their phenotypic effects in a field planting of 424 accessions. Soybean accessions carrying FA9H2 had significantly higher total fatty acid contents and lower protein contents than those carrying FA9H1 . FA9H2 was absent in wild soybeans but present in 13% of landraces and 26% of cultivars, suggesting that it may have been selected during soybean post-domestication improvement. FA9 therefore represents a useful genetic resource for molecular breeding of high-quality soybean varieties with specific seed storage profiles.

Multi-omics-driven advances in the understanding of triacylglycerol biosynthesis in oil seeds

Vegetable oils are rich sources of polyunsaturated fatty acids and energy as well as valuable sources of human food, animal feed, and bioenergy. Triacylglycerols, which are comprised of three fatty acids attached to a glycerol backbone, are the main component of vegetable oils. Here, we review the development and application of multiple-level omics in major oilseeds and emphasize the progress in the analysis of the biological roles of key genes underlying seed oil content and quality in major oilseeds. Finally, we discuss future research directions in functional genomics research based on current omics and oil metabolic engineering strategies that aim to enhance seed oil content and quality, and specific fatty acids components according to either human health needs or industrial requirements.

Soybean WRINKLED1 protein GmWRI1a promotes flowering under long-day conditions via regulating expressions of flowering-related genes

Flowering time is an important agronomic character that influences the adaptability and yield of soybean [Glycine max (L.) Merrill]. WRINKLED 1 (WRI1) plays an important regulatory role in plant growth and development. In this study, we found that the expression of GmWIR1a could be induced by long days. Compared with the wild type, transgenic soybean overexpressing GmWRI1a showed earlier flowering and maturity under long days but no significant changes under short days. Overexpression of GmWRI1a led to up-regulated expression of genes involved in the regulation of flowering time. The GmWRI1a protein was able to directly bind to the promoter regions of GmAP1, GmFUL1a, GmFUL2 and up-regulated their expression. GmCOL3 was identified by yeast one-hybrid library screening using the GmWRI1a promoter as bait. GmCOL3 was revealed to be a nucleus-localized protein that represses the transcription of GmWRI1a. Expression of GmCOL3 was induced by short days. Taken together, the results show that overexpression of GmWRI1a promotes flowering under long days by promoting the transcriptional activity of flowering-related genes in soybean, and that GmCOL3 binds to the GmWRI1a promoter and directly down-regulates its transcription. This discovery reveals a new function for GmWRI1a, which regulates flowering and maturity in soybean.

Regulation of seed traits in soybean

Soybean (Glycine max) is an essential economic crop that provides vegetative oil and protein for humans, worldwide. Increasing soybean yield as well as improving seed quality is of great importance. Seed weight/size, oil and protein content are the three major traits determining seed quality, and seed weight also influences soybean yield. In recent years, the availability of soybean omics data and the development of related techniques have paved the way for better research on soybean functional genomics, providing a comprehensive understanding of gene functions. This review summarizes the regulatory genes that influence seed size/weight, oil content and protein content in soybean. We also provided a general overview of the pleiotropic effect for the genes in controlling seed traits and environmental stresses. Ultimately, it is expected that this review will be beneficial in breeding improved traits in soybean.

Global Transcriptome and Co-Expression Network Analyses Revealed Hub Genes Controlling Seed Size/Weight and/or Oil Content in Peanut

Cultivated peanut (Arachis hypogaea L.) is an important economic and oilseed crop worldwide, providing high-quality edible oil and high protein content. Seed size/weight and oil content are two important determinants of yield and quality in peanut breeding. To identify key regulators controlling these two traits, two peanut cultivars with contrasting phenotypes were compared to each other, one having a larger seed size and higher oil content (Zhonghua16, ZH16 for short), while the second cultivar had smaller-sized seeds and lower oil content (Zhonghua6, ZH6). Whole transcriptome analyses were performed on these two cultivars at four stages of seed development. The results showed that ~40% of the expressed genes were stage-specific in each cultivar during seed development, especially at the early stage of development. In addition, we identified a total of 5356 differentially expressed genes (DEGs) between ZH16 and ZH6 across four development stages. Weighted gene co-expression network analysis (WGCNA) based on DEGs revealed multiple hub genes with potential roles in seed size/weight and/or oil content. These hub genes were mainly involved in transcription factors (TFs), phytohormones, the ubiquitin-proteasome pathway, and fatty acid synthesis. Overall, the candidate genes and co-expression networks detected in this study could be a valuable resource for genetic breeding to improve seed yield and quality traits in peanut.

Genetic regulatory networks of soybean seed size, oil and protein contents

As a leading oilseed crop that supplies plant oil and protein for daily human life, increasing yield and improving nutritional quality (high oil or protein) are the top two fundamental goals of soybean breeding. Seed size is one of the most critical factors determining soybean yield. Seed size, oil and protein contents are complex quantitative traits governed by genetic and environmental factors during seed development. The composition and quantity of seed storage reserves directly affect seed size. In general, oil and protein make up almost 60% of the total storage of soybean seed. Therefore, soybean's seed size, oil, or protein content are highly correlated agronomical traits. Increasing seed size helps increase soybean yield and probably improves seed quality. Similarly, rising oil and protein contents improves the soybean's nutritional quality and will likely increase soybean yield. Due to the importance of these three seed traits in soybean breeding, extensive studies have been conducted on their underlying quantitative trait locus (QTLs) or genes and the dissection of their molecular regulatory pathways. This review summarized the progress in functional genome controlling soybean seed size, oil and protein contents in recent decades, and presented the challenges and prospects for developing high-yield soybean cultivars with high oil or protein content. In the end, we hope this review will be helpful to the improvement of soybean yield and quality in the future breeding process.

Regulation of seed oil accumulation by lncRNAs in Brassica napus

BACKGROUND

Studies have indicated that long non-coding RNAs (lncRNAs) play important regulatory roles in many biological processes. However, the regulation of seed oil biosynthesis by lncRNAs remains largely unknown.

RESULTS

We comprehensively identified and characterized the lncRNAs from seeds in three developing stages in two accessions of Brassica napus (B. napus), ZS11 (high oil content) and WH5557 (low oil content). Finally, 8094 expressed lncRNAs were identified. LncRNAs MSTRG.22563 and MSTRG.86004 were predicted to be related to seed oil accumulation. Experimental results show that the seed oil content is decreased by 3.1-3.9% in MSTRG.22563 overexpression plants, while increased about 2% in MSTRG.86004, compared to WT. Further study showed that most genes related to lipid metabolism had much lower expression, and the content of some metabolites in the processes of respiration and TCA (tricarboxylic acid) cycle was reduced in MSTRG.22563 transgenic seeds. The expression of genes involved in fatty acid synthesis and seed embryonic development (e.g., LEC1) was increased, but genes related to TAG assembly was decreased in MSTRG.86004 transgenic seeds.

CONCLUSION

Our results suggest that MSTRG.22563 might impact seed oil content by affecting the respiration and TCA cycle, while MSTRG.86004 plays a role in prolonging the seed developmental time to increase seed oil accumulation.

Bioengineering of Soybean Oil and Its Impact on Agronomic Traits

Soybean is a major oil crop and is also a dominant source of nutritional protein. The 20% seed oil content (SOC) of soybean is much lower than that in most oil crops and the fatty acid composition of its native oil cannot meet the specifications for some applications in the food and industrial sectors. Considerable effort has been expended on soybean bioengineering to tailor fatty acid profiles and improve SOC. Although significant advancements have been made, such as the creation of high-oleic acid soybean oil and high-SOC soybean, those genetic modifications have some negative impacts on soybean production, for instance, impaired germination or low protein content. In this review, we focus on recent advances in the bioengineering of soybean oil and its effects on agronomic traits.

GmWRI1c Increases Palmitic Acid Content to Regulate Seed Oil Content and Nodulation in Soybean (Glycine max)

Soybean (Glycine max) is an important oil crop, but the regulatory mechanisms underlying seed oil accumulation remain unclear. We identified a member of the GmWRI1s transcription factor family, GmWRI1c, that is involved in regulating soybean oil content and nodulation. Overexpression of GmWRI1c in soybean hairy roots increased the expression of genes involved in glycolysis and de novo lipogenesis, the proportion of palmitic acid (16:0), and the number of root nodules. The effect of GmWRI1c in increasing the number of root nodules via regulating the proportion of palmitic acid was confirmed in a recombinant inbred line (RIL) population. GmWRI1c shows abundant sequence diversity and has likely undergone artificial selection during domestication. An association analysis revealed a correlation between seed oil content and five linked natural variations (Hap1/Hap2) in the GmWRI1c promoter region. Natural variations in the GmWRI1c promoter were strongly associated with the GmWRI1c transcript level, with higher GmWRI1c transcript levels in lines carrying GmWRI1c^Hap1 than in those carrying GmWRI1c^Hap2. The effects of GmWRI1c alleles on seed oil content were confirmed in natural and RIL populations. We identified a favourable GmWRI1c allele that can be used to breed new varieties with increased seed oil content and nodulation.

Progress in Soybean Genetic Transformation Over the Last Decade

Soybean is one of the important food, feed, and biofuel crops in the world. Soybean genome modification by genetic transformation has been carried out for trait improvement for more than 4 decades. However, compared to other major crops such as rice, soybean is still recalcitrant to genetic transformation, and transgenic soybean production has been hampered by limitations such as low transformation efficiency and genotype specificity, and prolonged and tedious protocols. The primary goal in soybean transformation over the last decade is to achieve high efficiency and genotype flexibility. Soybean transformation has been improved by modifying tissue culture conditions such as selection of explant types, adjustment of culture medium components and choice of selection reagents, as well as better understanding the transformation mechanisms of specific approaches such as Agrobacterium infection. Transgenesis-based breeding of soybean varieties with new traits is now possible by development of improved protocols. In this review, we summarize the developments in soybean genetic transformation to date, especially focusing on the progress made using Agrobacterium-mediated methods and biolistic methods over the past decade. We also discuss current challenges and future directions.