Search

Enhancing soybean (Glycine max) oil production is crucial to meet the market demand of vegetable oil. Diacylglycerol acyltransferase (DGAT) catalyzes the final acylation reaction of triacylglycerol (TAG) synthesis, acting as one of the rate-limiting enzymes for oil biosynthesis in plant seeds. Here, a cDNA clone VgDGAT1A encoding the DGAT1 protein was isolated from the high oil plant Vernonia galamensis. VgDGAT1A was specifically overexpressed in soybean seeds, and several high-generation transgenic lines (T7) were obtained by continuous selection. qPCR analysis showed that VgDGAT1A was highly expressed in the mid-development stage (30-45 DAF) of the transgenic seeds. Accordingly, the DGAT enzyme activity in the transgenic seeds was increased by 7.8 folds in comparison with the wild-type controls. Seed oil and starch contents were, respectively, increased by 5.1% (Dry weight) and reduced by 2%-3% in the transgenic soybeans. Importantly, protein content was not significantly different between transgenic and control seeds. Seed weight and germination rate of the transgenic lines exhibited no negative effect. Fatty acid profiling demonstrated that antioxidant oleic acid (C18:1Δ9) content in the transgenic seed oil was elevated by 8.2% compared to the control, and correspondingly, easily-oxidized linoleic acid (C18:2Δ9,12) and linolenic acid (C18:3Δ9,12,15) were decreased by 6% and 2% respectively. Taken together, seed-specific overexpression of an exogenous VgDGAT1A gene can break the negative linkage of oil and protein contents in soybean seeds, indicating that engineering of this highly-active DGAT enzyme is an effective strategy to improve oil yield and nutritional value in oilseeds.为提高大豆Glycine max 种子含油量和营养品质，文中以二酰甘油酰基转移酶1 (Diacylglycerol acyltransferase 1，DGAT1) 基因为遗传修饰靶标。将来自高油植物斑鸠菊Vernonia galamensis L.编码DGAT1 酶蛋白的cDNA 克隆VgDGAT1A 在大豆种子特异超表达。连续选择获得高代 (T7) VgDGAT1A 转基因大豆株系。转基因株系表型鉴定显示，在大豆种子发育中期 (30–45 DAF)，VgDGAT1A 高表达，相应地DGAT 酶活性是非转基因野生型和空载体转化对照的7.8 倍。转基因成熟种子含油量比对照提高了5.1%，淀粉含量比对照减少2%–3%，蛋白质含量与对照无显著差异。此外，转基因大豆种子百粒重 (14.5 g) 和种子萌发率 (95.6%) 与对照亦无明显差异。种子油脂脂肪酸成分分析显示，转基因大豆种子油中抗氧化的油酸 (C18:1Δ9) 含量比对照提高8.2%，相应地易氧化的亚油酸 (C18:2Δ9,12) 和亚麻酸 (C18:3Δ9,12,15) 分别减少6%和2%。这些数据表明，种子特异超表达外源VgDGAT1A 基因，打破了大豆种子含油量和蛋白质含量的负连锁，显著提高种子含油量且未导致蛋白含量降低。转基因大豆种子重量和萌发率亦未显负效应，而且种子油脂抗氧化性和营养品质得以改善。研究表明应用这一高酶活性VgDGAT1A 的基因工程是提高种子含油量和改善油脂品质的一条有效途径。.

The basic leucine-region zipper (bZIP) transcription factors (TFs) act as crucial regulators in various biological processes and stress responses in plants. Currently, bZIP family members and their functions remain elusive in the green unicellular algae Chlamydomonas reinhardtii, an important model organism for molecular investigation with genetic engineering aimed at increasing lipid yields for better biodiesel production. In this study, a total of 17 C. reinhardtii bZIP (CrebZIP) TFs containing typical bZIP structure were identified by a genome-wide analysis. Analysis of the CrebZIP protein physicochemical properties, phylogenetic tree, conserved domain, and secondary structure were conducted. CrebZIP gene structures and their chromosomal assignment were also analyzed. Physiological and photosynthetic characteristics of C. reinhardtii under salt stress were exhibited as lower cell growth and weaker photosynthesis, but increased lipid accumulation. Meanwhile, the expression profiles of six CrebZIP genes were induced to change significantly during salt stress, indicating that certain CrebZIPs may play important roles in mediating photosynthesis and lipid accumulation of microalgae in response to stresses. The present work provided a valuable foundation for functional dissection of CrebZIPs, benefiting the development of better strategies to engineer the regulatory network in microalgae for enhancing biofuel and biomass production.

The basic leucine-region zipper (bZIP) transcription factors (TFs) act as crucial regulators in various biological processes and stress responses in plants. Currently, bZIP family members and their functions remain elusive in the green unicellular algae Chlamydomonas reinhardtii, an important model organism for molecular investigation with genetic engineering aimed at increasing lipid yields for better biodiesel production. In this study, a total of 17 C. reinhardtii bZIP (CrebZIP) TFs containing typical bZIP structure were identified by a genome-wide analysis. Analysis of the CrebZIP protein physicochemical properties, phylogenetic tree, conserved domain, and secondary structure were conducted. CrebZIP gene structures and their chromosomal assignment were also analyzed. Physiological and photosynthetic characteristics of C. reinhardtii under salt stress were exhibited as lower cell growth and weaker photosynthesis, but increased lipid accumulation. Meanwhile, the expression profiles of six CrebZIP genes were induced to change significantly during salt stress, indicating that certain CrebZIPs may play important roles in mediating photosynthesis and lipid accumulation of microalgae in response to stresses. The present work provided a valuable foundation for functional dissection of CrebZIPs, benefiting the development of better strategies to engineer the regulatory network in microalgae for enhancing biofuel and biomass production.

Plant-specific GRAS transcription factors regulate various biological processes in plant growth, development and stress responses. However, this important gene family was not fully characterized in pepper (Capsicum annuumL.), an economically important vegetable crop. Here, a total of 50 CaGRAS members were identified in pepper genome and renamed by their respective chromosomal distribution. Genomic organization revealed that mostCaGRASgenes (84%) have no intron. Phylogenetic analysis divided pepper CaGRAS members into 10 subfamilies, with each having distinct conserved domains and functions. For the expansion of theGRASgenes in pepper, segmental duplication contributed more than tandem duplication did. Gene expression analysis in various tissues demonstrated that most ofCaGRASgenes exhibited a tissue- and development stage-specific expression pattern, uncovering their potential functions in pepper growth and development. Moreover, 21CaGRASgenes were differentially expressed under cold, drought, salt and gibberellin acid (GA) treatments, indicating that they may implicated in plant response to abiotic stress. Notably, GA responsivecis-elements were detected in the promoter regions of the majority ofCaGRASgenes, suggesting that CaGRAS may involve in signal cross-talking. The first comprehensive analysis of GRAS gene family in pepper genome by this study provide insights into understanding the GRAS-mediated regulation network, benefiting the genetic improvements in pepper and some other relative plants.

The plant-specific WRINKLED1 (WRI1) is a member of the AP2/EREBP class of transcription factors that positively regulate oil biosynthesis in plant tissues. Limited information is available for the role of WRI1 in oil biosynthesis in castor bean (Ricinus connunis L.), an important industrial oil crop. Here, we report the identification of two alternatively spliced transcripts of RcWRI1, designated as RcWRI1-A and RcWRI1-B. The open reading frames of RcWRI1-A (1341 bp) and RcWRI1-B (1332 bp) differ by a stretch of 9 bp, such that the predicted RcWRI1-B lacks the three amino acid residues “VYL” that are present in RcWRI1-A. The RcWRI1-A transcript is present in flowers, leaves, pericarps and developing seeds, while the RcWRI1-B mRNA is only detectable in developing seeds. When the two isoforms were individually introduced into an Arabidopsis wri1-1 loss-of-function mutant, total fatty acid content was almost restored to the wild-type level, and the percentage of the wrinkled seeds was largely reduced in the transgenic lines relative to the wri1-1 mutant line. Transient expression of each RcWRI1 splice isoform in N. benthamiana leaves upregulated the expression of the WRI1 target genes, and consequently increased the oil content by 4.3–4.9 fold when compared with the controls, and RcWRI1-B appeared to be more active than RcWRI1-A. Both RcWRI1-A and RcWRI1-B can be used as a key transcriptional regulator to enhance fatty acid and oil biosynthesis in leafy biomass.