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Summary: Accumulation of triacylglycerols (TAGs) is crucial during various stages of plant development. In Arabidopsis, two enzymes share overlapping functions to produce TAGs, namely acyl‐CoA:diacylglycerol acyltransferase 1 (DGAT1) and phospholipid:diacylglycerol acyltransferase 1 (PDAT1). Loss of function of both genes in a dgat1‐1/pdat1‐2 double mutant is gametophyte lethal. However, the key regulatory elements controlling tissue‐specific expression of either gene has not yet been identified.We transformed a dgat1‐1/dgat1‐1//PDAT1/pdat1‐2 parent with transgenic constructs containing the Arabidopsis DGAT1 promoter fused to the AtDGAT1 open reading frame either with or without the first intron.Triple homozygous plants were obtained, however, in the absence of the DGAT1 first intron anthers fail to fill with pollen, seed yield is c. 10% of wild‐type, seed oil content remains reduced (similar to dgat1‐1/dgat1‐1), and non‐Mendelian segregation of the PDAT1/pdat1‐2 locus occurs. Whereas plants expressing the AtDGAT1pro:AtDGAT1 transgene containing the first intron mostly recover phenotypes to wild‐type.This study establishes that a combination of the promoter and first intron of AtDGAT1 provides the proper context for temporal and tissue‐specific expression of AtDGAT1 in pollen. Furthermore, we discuss possible mechanisms of intron mediated regulation and how regulatory elements can be used as genetic tools to functionally replace TAG biosynthetic enzymes in Arabidopsis. [ABSTRACT FROM AUTHOR]

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Erucic acid concentration in oil of most camelina (Camelina sativa L. Crantz) genotypes exceeds the 2% threshold allowed by the U.S. Food and Drug Administration (FDA) for use as a food additive. Lowering erucic acid concentration below the FDA threshold enables marketing camelina as edible oil for human consumption, greatly expanding potential uses to include food ingredients such as marinades, salad dressings, spreads, and dips. A mutant camelina line, LE1914, created via ethyl methanesulfonate mutagenesis at one FAE1 locus (FAE1‐B), produces seed oil with low (∼0.6%) erucic acid concentration (LE). This mutant trait was introgressed into elite camelina breeding lines to create LE lines adapted to Pacific Northwest dryland agriculture. These LE lines were evaluated in a large, replicated field trial in Pullman, WA, in 2019. One line, 'WA‐LE1' (Reg. no. CV‐15, PI 699653), exhibited agronomic performance similar to check cultivars while maintaining the low (∼0.6%) erucic acid concentration necessary for FDA approval as a food additive. WA‐LE1 is an edible oil camelina cultivar that also contains the Group 2 herbicide resistance trait of WA‐HT1 that was released in 2018. WA‐LE1 should expand marketability and increase profitability of camelina crops in the Pacific Northwest. Core Ideas: A mutation causing low erucic acid content was incorporated into a highly productive camelina cultivar, 'WA‐LE1'.The low erucic acid trait is required by the FDA for food use.A food market will expand the utility of camelina beyond biofuels.'WA‐LE1' carries a gene for tolerance to Group 2 herbicides. [ABSTRACT FROM AUTHOR]

Summary: Arbuscular mycorrhizal fungi (AMF) are among the most ancient, widespread and functionally important symbioses on Earth that help feed the world. Yet, mass‐production of clean (i.e. in vitro produced), safe and robust inoculum at affordable costs remains a critical challenge. Very recently, Luginbuehl et al. (2017) found that plants supply lipids to the symbiotic partner, thus 'providing the AMF with a robust source of carbon for their metabolic needs'. Hence, engineering plants for enhanced delivery of lipids to AMF could represent an innovative avenue to produce a novel generation of high‐quality and cost‐effective bio‐fortified AMF inoculants for application in agro‐ecosystems. [ABSTRACT FROM AUTHOR]

Stearoyl-acyl carrier protein desaturase ( SACPD) activity is essential for production of the major unsaturated fatty acids ( UFAs) in plant lipids. We report here the characterization of three SACPD genes from Nicotiana benthamiana, Nb SACPD- A, - B, and - C. All three genes share high similarity to At SSI2/ FAB2 (Suppressor of Salicylic acid-Insensitivity2/Fatty Acid Biosynthesis2), the primary SACPD isoform in Arabidopsis. Knocking down the expression of individual or combinations of Nb SACPDs by an artificial micro RNA approach resulted in significantly reduced accumulation of 18 C UFAs and elevated levels of 18:0- FA (Fatty acids) in leaves, indicating that all three genes participated in fatty acid desaturation. The triple knockdown ( KD) plants displayed severe growth phenotypes, including spontaneous cell death and dwarfing. While no vegetative morphologic abnormality was observed in Nb SACPD-A, - B, or - C KD plants, strikingly, Nb SACPD-C KD plants produced small fruits with aborted ovules. Reciprocal crosses with wild-type and Nb SACPD-C KD plants revealed that knocking down Nb SACPD-C expression caused female, but not male, sterility. Furthermore, arrested ovule development and significantly altered lipid composition in ovaries were observed in Nb SACPD- C KD plants, consistent with the predominant Nb SACPD- C expression in ovules. The ovule development defect was fully complemented by coexpressing an ami RNA-resistant Nb SACPD-C variant in the Nb SACPD-C KD background, further supporting a specific requirement for Nb SACPD-C in female fertility. Our results thus indicated that Nb SACPD-C plays a critical role maintaining membrane lipid composition in ovule development for female fertility in N. benthamiana, complementing and extending prior understanding on the well-demonstrated roles of SACPDs in biotic and abiotic stresses. [ABSTRACT FROM AUTHOR]

Summary Engineering of oilseed plants to accumulate unusual fatty acids (FAs) in seed triacylglycerol (TAG) requires not only the biosynthetic enzymes for unusual FAs but also efficient utilization of the unusual FAs by the host-plant TAG biosynthetic pathways. Competing pathways of diacylglycerol (DAG) and subsequent TAG synthesis ultimately affect TAG FA composition. The membrane lipid phosphatidylcholine (PC) is the substrate for many FA-modifying enzymes (desaturases, hydroxylases, etc.) and DAG can be derived from PC for TAG synthesis. The relative proportion of PC-derived DAG versus de novo synthesized DAG utilized for TAG synthesis, and the ability of each pathway to utilize unusual FA substrates, are unknown for most oilseed plants, including Arabidopsis thaliana. Through metabolic labeling experiments we demonstrate that the relative flux of de novo DAG into the PC-derived DAG pathway versus direct conversion to TAG is ∼14/1 in wild-type Arabidopsis. Expression of the Ricinus communis FA hydroxylase reduced the flux of de novo DAG into PC by ∼70%. Synthesis of TAG directly from de novo DAG did not increase, resulting in lower total synthesis of labeled lipids. Hydroxy-FA containing de novo DAG was rapidly synthesized, but it was not efficiently accumulated or converted to PC and TAG, and appeared to be in a futile cycle of synthesis and degradation. However, FA hydroxylation on PC and conversion to DAG allowed some hydroxy-FA to accumulate in sn-2 TAG. Therefore, the flux of DAG through PC represents a major bottleneck for the accumulation of unusual FAs in TAG of transgenic Arabidopsis seeds. [ABSTRACT FROM AUTHOR]

The article discusses an experimental study on the effects of material property, process parameters, and weld gap thickness on the strength and microstructure of contour welds made of polycarbonate (PC), polyamide 6 (PA6) and PA6 reinforced with 30 percent glass fiber. Assessment of the weld shear strength was accomplished using lap specimens with weld lines parallel to the load direction during testing. The results show that gap bridging improved with low concentrations of laser absorbing pigment accompanied by high laser power.