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Abstract Arabidopsis is wildly used as a model plant and camelina is increasingly used for oilseed research and applications. Although the Arabidopsis genome has been sequenced for two decades, the functions of many lipid‐related genes and their regulators have not been well characterized. Improvements in the efficiency and accuracy of gene investigations are key to effective discovery of gene function and downstream bioengineering of plant oil quantity and quality. In this study, a visible marker was used to quickly identify transgenic T1 seeds and a method has been developed to phenotype fatty acid compositions and oil content of single T1 seeds. A whole seed direct transmethylation method was first optimized with multiple seeds and incubation at 85°C for 2 hours in a transmethylation solvent (5% H2SO4 in methanol with 30% toluene cosolvent) is recommended. Based on this method, a single Arabidopsis seed mini‐transmethylation (SAST) method has been established in a 1.5 ml GC sample vial with 200 μl transmethylation solvent. Characteristics of the method were evaluated and it was used to phenotype transgenic T1 seeds expressing AtFAD2 or RcWRI1. Our results indicate that fatty acid composition of T1 individual seeds are consistent with those of pools of multiple seeds from higher generations. However, oil content per individual seed varied substantially and therefore pooling five seeds is recommended for phenotyping oil content of T1 seeds. Additionally, a whole camelina single‐seed direct transmethylation was evaluated and results confirm its feasibility. The suitability of partial seed analysis of camelina was investigated but variation in composition of different seed tissues limits this approach.

[This corrects the article DOI: 10.1371/journal.pgen.1003064.].

Unicellular marine algae have promise for providing sustainable and scalable biofuel feedstocks, although no single species has emerged as a preferred organism. Moreover, adequate molecular and genetic resources prerequisite for the rational engineering of marine algal feedstocks are lacking for most candidate species. Heterokonts of the genus Nannochloropsis naturally have high cellular oil content and are already in use for industrial production of high-value lipid products. First success in applying reverse genetics by targeted gene replacement makes Nannochloropsis oceanica an attractive model to investigate the cell and molecular biology and biochemistry of this fascinating organism group. Here we present the assembly of the 28.7 Mb genome of N. oceanica CCMP1779. RNA sequencing data from nitrogen-replete and nitrogen-depleted growth conditions support a total of 11,973 genes, of which in addition to automatic annotation some were manually inspected to predict the biochemical repertoire for this organism. Among others, more than 100 genes putatively related to lipid metabolism, 114 predicted transcription factors, and 109 transcriptional regulators were annotated. Comparison of the N. oceanica CCMP1779 gene repertoire with the recently published N. gaditana genome identified 2,649 genes likely specific to N. oceanica CCMP1779. Many of these N. oceanica-specific genes have putative orthologs in other species or are supported by transcriptional evidence. However, because similarity-based annotations are limited, functions of most of these species-specific genes remain unknown. Aside from the genome sequence and its analysis, protocols for the transformation of N. oceanica CCMP1779 are provided. The availability of genomic and transcriptomic data for Nannochloropsis oceanica CCMP1779, along with efficient transformation protocols, provides a blueprint for future detailed gene functional analysis and genetic engineering of Nannochloropsis species by a growing academic community focused on this genus.

Diverse fatty acid structures from different plant species are important renewable resources for industrial rawmaterials and as liquid fuels with high energy density. Because of its immense geographical and topographical variations, China is a country with enormous diversity of plant species, including large numbers of plants endemic to China. The richness of this resource of species provides a wide range of fatty acids in seeds or other tissues, many of which have been identified by Chinese scientists. However, in the past, most publications describing analysis of these plants were written in Chinese, making access for researchers from other countries difficult. In this study, we investigated reports on seed and fruit oil fatty acids as described in Chinese literature. Six books and more than one thousand papers were collected and the identified fatty acids and relevant plant species were summarized. In total, about 240 fatty acids from almost 1,500 plant species were identified from available Chinese literature. Only about one third of these species were retrieved in the PhyloFAdb and SOFA online databases of plant fatty acids. By referring to a summary of plant species endemic to China, 277 Chinese endemic species from 68 families have been surveyed for seed fatty acids. These account for <2% of total Angiosperm species endemic to China indicating the scope of species yet to be surveyed. To discover additional new fatty acid structures thatmight benefit society, it is important in the future to study oilseed fatty acids of the many other Chinese endemic plants. As an example, seeds of five unsurveyed species were collected and their fatty acids were analyzed. Ricinoleic acid was detected for the first time in the Salicaceae family. [ABSTRACT FROM AUTHOR]

Abstract  The regulation of genes involved in primary lipid metabolism in plants is much less well understood than that in many other pathways in plant biology. In the investigation reported here, we have characterized transcriptional regulatory mechanisms controlling seed-specific FAD2 expression in sesame (Sesamum indicum). FAD2 codes for extra-plastidial FAD2 desaturase, which catalyzes the conversion of oleic acid to linoleic acid. Promoter analysis of the sesame FAD2 gene (SeFAD2) using the β-glucuronidase (GUS) reporter system demonstrated that the − 660 to − 180 promoter region functions as a negative cis-element in the seed-specific expression of the SeFAD2 gene. Sesame and Arabidopsis FAD2 genes harbor one large intron within their 5′-untranslated region. These introns conferred up to 100-fold enhancement of GUS expression in transgenic Arabidopsis tissues as compared with intron-less controls. Prerequisite cis-elements for the SeFAD2 intron-mediated enhancement of gene expression and the promoter-like activity of SeFAD2 intron were identified. SeFAD2 transcripts were induced by abscisic acid (ABA) in developing sesame seeds, and the − 660 to − 548 and − 179 to − 53 regions in the SeFAD2 promoter were implicated in ABA-responsive signaling. Theses observations indicate that an intron-mediated regulatory mechanism is involved in controlling not only the seed-specific expression of the SeFAD2 gene but also the expression of plant FAD2 genes, which are essential for the synthesis of polyunsaturated fatty acids. [ABSTRACT FROM AUTHOR]