Metabolic Engineering to Increase the Corn Seed Storage Lipid Quantity and Change Its Compositional Quality

Abstract

Given limited global food supplies and the fact that the global population is expected to double by 2050, there is an urgent need for the development of high‐calorie foods, including culinary oils. The seeds of oil crops contain high‐energy density oil composed of triacylglycerides (TAGs) at up to 80% by dry mass. However, maize (Zea mays L.) seeds are relatively poor in calorie and nutritional values. Therefore, in this report, we address this constraint via metabolic engineering to improve maize seed lipids including TAG and seed TAG nutritional values by overexpression of three major genes, including: (i) the Arabidopsis thaliana (L.) Heynh. diacylglycerol acyltransferase 1 (AtDGAT1), a gene that catalyzes the TAG biosynthesis final step prior to packaging of TAGs into oil bodies; (ii) the transcription factor WRINKLED 1 (WRI1), which promotes the regulation of the expression of genes involved in fatty acid biosynthesis; and (i) the A. thaliana oleosin (AtOleosin) gene, a gene coding for a protein that protects TAGs from degradation. The overexpression of the above three genes, and probably certain unintentional in vitro culture genetic variabilities, resulted in 117% increase of seed TAGs and 25% increase in total oil contents when compared with the wild‐type control corn seeds. In addition, the above genetic modifications led to major shifts in the fatty acid profiles in favor of human health.

Introducing sorghum DREB2 gene in maize (Zea mays L.) to improve drought and salinity tolerance

“…Rooting took place on the MS media containing 1 mg/L IBA (Figure 2C). We followed all details according to our previous studies 26,33,34 …”

“…For root induction, 1 mg/L indole‐3‐butyric acid (IBA) was used. Hardening regenerated plants was performed based on our previous work 33,34 …”

Properties and Biotechnological Applications of Acyl‐CoA:diacylglycerol Acyltransferase and Phospholipid:diacylglycerol Acyltransferase from Terrestrial Plants and Microalgae

“…The overexpression of T. majus DGAT1 in Arabidopsis, high‐erucic‐acid rapeseed, and canola‐type B. napus also led to enhanced seed oil content (Xu et al, ). Following these aforementioned studies, many groups have further used DGAT1 from different species to boost seed content in various crops such as G. max (Hatanaka et al, ; Roesler et al, ), B. juncea (Savadi et al, ), Z. mays (Alameldin et al, ), C. sativa (Kim et al, ), and Jatropa curcas (Maravi et al, ). Moreover, overexpression of DGAT1 from microalgae, such as Chlorella ellipsoidea and Nannochloropsis oceanica , also led to increased oil content in Arabidopsis and B. napus (Guo et al, ; Zienkiewicz et al, ).…”

Kinetic improvement of an algal diacylglycerol acyltransferase 1 via fusion with an acyl‐CoA binding protein

“…In microalgae, on the other hand, one or two copies of DGAT1 and several copies of DGAT2 were found to likely contribute to the complexity of TAG formation, although their physiological roles remain ambiguous (Turchetto‐Zolet et al , ; Chen and Smith, ; Gong et al , ; Liu and Benning, ; Liu et al , ; Xu et al , ; Mao et al , ). Given the importance of the enzyme in governing the flux of substrates into TAG, over‐expression of DGAT cDNAs has been used to manipulate oil production in the seeds of Arabidopsis thaliana and oilseed crops such as soybean ( Glycine max ), B. napus , corn ( Zea mays ) and Camelina sativa (Jako et al , ; Lardizabal et al , ; Weselake et al , ; Oakes et al , ; Li et al , ; Roesler et al , ; Kim et al , ), in the leaves of Nicotiana tabacum , N. benthamiana and Z. mays (Bouvier‐Navé et al , ; Alameldin et al , ; Chen et al , ; Vanhercke et al , ), and in oleaginous yeast (Greer et al , ; Chen et al , ) and several microalgae including Chlamydomonas reinhardtii , Phaeodactylum tricornutum and Nannochloropsis oceanica (Iwai et al , ; Xin et al , , ; Zulu et al , ; Mao et al , ).…”