| 1. |
- Li, Xue-Yuan, et al.
(författare)
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Genetic transformation of the oilseed crop Crambe abyssinica
- 2010
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Ingår i: Plant Cell, Tissue and Organ Culture. - : Springer Science and Business Media LLC. - 0167-6857 .- 1573-5044. ; 100, s. 149-156
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Tidskriftsartikel (refereegranskat)abstract
- Engineering oilseed crops for industrial purposes requires a suitable crop that does not outcross to any food oilseed crop, thus eliminating problems of gene flow. Crambe abyssinica is such a dedicated crop as it does not hybridize with any existing food oilseed crops. However, lack of regeneration and transformation protocols has limited the use of C. abyssinica in genetic manipulation studies. In this study, efficient regeneration and transformation protocols for Crambe have been developed. Hypocotyls of C. abyssinica cv. Galactica were incubated on a Murashige and Skoog medium supplemented with various plant growth regulators (PGRs). Among the different PGR combinations tested, 10 mu M thidiazuron and 2.7 mu M alpha-naphthaleneacetic acid promoted highest frequency of regeneration, up to 60%. Among six Agrobacterium stains evaluated, each harbouring the cloning vector containing the neomycin phosphotransferase (nptII) and beta-glucuronidase (gus) genes. EHA101 and AGL-1 yielded the highest transformation frequencies of 1.3 and 2.1%, respectively. Putative transgenic lines were recovered, and confirmed as transgenic by Southern blot analysis. Subsequently, Agrobacterium-mediated transformation of hypocotyls of cv. Galactica with constructs harbouring the wax synthase and fatty acid reductase genes have also successfully recovered confirmed transgenic plants carrying these transgenes.
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| 2. |
- Nsibande, Busisiwe, et al.
(författare)
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In Vitro Regeneration of Endangered Medicinal Hypoxis Species
- 2015
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Ingår i: American Journal of Plant Sciences. - : Scientific Research Publishing, Inc.. - 2158-2742 .- 2158-2750. ; 6, s. 2585-2595
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Tidskriftsartikel (refereegranskat)abstract
- The genus Hypoxis contains some of southern Africa's most important wild medicinal species, a situation that has placed most of them amongst endangered species facing extinction. In this study, four Hypoxis species collected from Swaziland: H. argentea, H. filiformis, H. acuminata and H. hemerocallidea, were included to assess their potential for in vitro propagation in order to efficiently conserve these species in the future. Among all types of explants tested only corm explants and seeds gave rise to shoots under the in vitro conditions. For the corm establishment, H. filiformis was the most in vitro responsive species, which had 100% shoot regeneration with high shoot number when cultured on the MS medium supplemented with 3 mg·l-1 kinetin with a piece of shoot attached, while the highest mean shoot number (17) was obtained on the same medium, but with no shoot attachment to the corm explants. H. argentea was the next most responsive species in vitro with up to 70% establishment, while the other two species had only up to 20% of in vitro establishment. For the seed explants, up to 29% seed germination was obtained for H. argentea when the seed coats were crushed before the in vitro culture. The regenerated shoots were rooted in vitro and acclimatized in the greenhouse successfully
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| 3. |
- Zhu, Li-Hua, et al.
(författare)
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Can Arabidopsis AP1 Gene Shorten the Juvenility of Apple?
- 2009
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 829, s. 259-264
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Konferensbidrag (refereegranskat)abstract
- Shortening of the juvenile phase is of great importance for apple breeding. Compared to conventional breeding methods, gene technology is more straightforward in reducing juvenility, as it can directly regulate expression of flowering-time genes. In model plant Arabidopsis, a number of flowering-time genes have been identified and characterised. Some of them have also been isolated from other species. Regulation of these genes has been proved to promote early flowering in a number of plant species. In this study, we have introduced the Arabidopsis APETALA1 (AP1) gene into the apple rootstock M26. The transgenic plants have been grown in the greenhouse for two years; however, no early flowering has been observed, although the AP1 gene is constitutively expressed in the transgenic clones, confirmed by RT-PCR analysis.
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| 4. |
- Zhu, Li-Hua, et al.
(författare)
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Plant Size Control in Apple through Genetic Engineering
- 2009
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 839, s. 689-694
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Konferensbidrag (refereegranskat)abstract
- Tree size control is essential for modern apple production. Chemical controls and different managements have been practically used in commercial production of apple rootstocks and cultivars in order to generate dwarf trees. However, these practices are either inefficient or unfriendly to human health and environment. In contrast, genetic engineering offers a better possibility to improve plant properties. By introducing well-characterised genes that control the growth vigour, it is possible to dwarf an existing genotype without disturbing its main genetic background. Up to now, some genes have been introduced into different plant species and proved to be effective in reducing plant size. Among the genes tested, the rolC, gai and GA oxidase have shown to be able to reduce plant size in most cases. In our previous studies, we have introduced the rolC and gai genes into apple rootstocks and cultivars. Both in vitro and grown analysis in greenhouse have shown that transgenic plants with one of these genes did display reduced plant height in most cases. Since plant height is mainly controlled by gibberellins, regulation of GA biosynthesis would be a better way to control plant size in the future.
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| 5. |
- Guan, Rui, et al.
(författare)
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Bottlenecks in erucic acid accumulation in genetically engineered ultrahigh erucic acid Crambe abyssinica
- 2014
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Ingår i: Plant Biotechnology Journal. - : Wiley. - 1467-7644 .- 1467-7652. ; 12, s. 193-203
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Tidskriftsartikel (refereegranskat)abstract
- Erucic acid is a valuable industrial fatty acid with many applications. The main producers of this acid are today high erucic rapeseed (Brassica napus) and mustard (Brassica juncea), which have 45%-50% of erucic acid in their seed oils. Crambe abyssinica is an alternative promising producer of this acid as it has 55%-60% of erucic acid in its oil. Through genetic modification (GM) of three genes, we have previously increased the level of erucic acid to 71% (68mol%) in Crambe seed oil. In this study, we further investigated different aspects of oil biosynthesis in the developing GM Crambe seeds in comparison with wild-type (Wt) Crambe, rapeseed and safflower (Carthamus tinctorius). We show that Crambe seeds have very low phosphatidylcholine-diacylglycerol interconversion, suggesting it to be the main reason why erucic acid is limited in the membrane lipids during oil biosynthesis. We further show that GM Crambe seeds have slower seed development than Wt, accompanied by slower oil accumulation during the first 20days after flowering (DAF). Despite low accumulation of erucic acid during early stages of GM seed development, nearly 86mol% of all fatty acids accumulated between 27 and 50 DAF was erucic acid, when 40% of the total oil is laid down. Likely bottlenecks in the accumulation of erucic acid during early stages of GM Crambe seed development are discussed.
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| 6. |
- Li, Xue-Yuan, et al.
(författare)
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Combination of modern plant breeding and enzyme technology to obtain highly enriched erucic acid from Crambe oil
- 2016
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Ingår i: Sustainable Chemical Processes. - : Springer Science and Business Media LLC. - 2043-7129. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Background Fatty acids from vegetable oils are useful building blocks for industrial materials. The purpose of this work was to prepare erucic acid with high purity from a vegetable oil. High purity erucic acid is used for the production of erucamide with applications in plastics manufacturing. A newly developed transgenic Crambe line produces seed oil with 68% erucic acid compared to 53% in the wild type oil. Results Further enrichment of erucic acid from Crambe (wild type and transgenic) oil was achieved by selective enzymatic hydrolysis. UsingCandida rugosalipase as catalyst, other fatty acids were preferentially hydrolysed from the triacylglycerols and erucic acid was enriched in the acylglycerol fraction. The highest content of erucic acid achieved in that fraction was 95%. Conclusions The combination of modern plant breeding and enzyme technology is a promising approach for preparation of fatty acids of high purity.
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| 7. |
- Li, Xue-Yuan, et al.
(författare)
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Development of Industrial Oil Crop Crambe abyssinica for Wax Ester Production through Metabolic Engineering and Cross Breeding
- 2019
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Ingår i: Plant and Cell Physiology. - : Oxford University Press (OUP). - 0032-0781 .- 1471-9053. ; 60, s. 1274-1283
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Tidskriftsartikel (refereegranskat)abstract
- As an important industrial feedstock, wax esters ( WEs) have been used as lubricants in a number of technical processes. There is however currently no large-scale biological source for WE production and alteration in metabolic pathways of plant oils for producing WEs could be attractive to the commercial markets. Here, we present the breeding results of long-term studies on successful development of new crambe lines producing WEs through genetic engineering and cross breeding. The transgenic crambe lines producing WEs at over 25% of the total seed oil were first generated by introduction of the jojoba WE biosynthetic genes ScFAR and ScWS. Further improvement of the lines aiming at improving oxidative stability of WEs was achieved through introducing the CaFAD2-RNAi gene into these lines by crossing. The hybrid lines possessed similar agronomic traits to the wild type and a stable level of WEs over several generations, suggesting a high potential of crambe as an industrial crop for WE production.
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| 8. |
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| 9. |
- Li, Xue-Yuan, et al.
(författare)
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Development of ultra-high erucic acid oil in the industrial oil crop Crambe abyssinica
- 2012
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Ingår i: Plant Biotechnology Journal. - : Wiley. - 1467-7644 .- 1467-7652. ; 10, s. 862-870
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Tidskriftsartikel (refereegranskat)abstract
- Erucic acid (22 : 1) is a major feedstock for the oleochemical industry. In this study, a gene stacking strategy was employed to develop transgenic Crambe abyssinica lines with increased 22 : 1 levels. Through integration of the LdLPAAT, BnFAE1 and CaFAD2-RNAi genes into the crambe genome, confirmed by Southern blot and qRT-PCR, the average levels of 18 : 1, 18 : 2 and 18 : 3 were markedly decreased and that of 22 : 1 was increased from 60% in the wild type to 73% in the best transgenic line of T4 generation. In single seeds of the same line, the 22 : 1 level could reach 76.9%, an increase of 28.0% over the wild type. The trierucin amount was positively correlated to 22 : 1 in the transgenic lines. Unlike high erucic rapeseed, the wild-type crambe contains 22 : 1 in the seed phosphatidylcholine and in the sn-2 position of triacylglycerols (5% and 8%, respectively). The transgenic line with high 22 : 1 had decreased 22 : 1 level in phosphatidylcholine, and this was negatively correlated with the 22 : 1 level at the sn-2 position of TAG. The significances of this study include (i) achieving an unprecedented level of 22 : 1 in an oil crop; (ii) disclosing mechanisms in the channelling of a triacylglycerol-specific unusual fatty acid in oil seeds; (iii) indicating potential limiting factors involved in the erucic acid biosynthesis and paving the way for further increase of this acid and (iv) development of an added value genetically modified oil crop having no risk of gene flow into feed and food crops.
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| 10. |
- Li, Xue-Yuan, et al.
(författare)
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Down-regulation of crambe fatty acid desaturase and elongase in Arabidopsis and crambe resulted in significantly increased oleic acid content in seed oil
- 2016
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Ingår i: Plant Biotechnology Journal. - : Wiley. - 1467-7644 .- 1467-7652. ; 14, s. 323-331
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Tidskriftsartikel (refereegranskat)abstract
- High oleic oil is an important industrial feedstock that has been one of the main targets for oil improvement in a number of oil crops. Crambe (Crambe abyssinica) is a dedicated oilseed crop, suitable for industrial oil production. In this study, we down-regulated the crambe fatty acid desaturase (FAD) and fatty acid elongase (FAE) genes for creating high oleic seed oil. We first cloned the crambe CaFAD2, CaFAD3 and CaFAE1 genes. Multiple copies of each of these genes were isolated, and the highly homologous sequences were used to make RNAi constructs. These constructs were first tested in Arabidopsis, which led to the elevated oleic or linoleic levels depending on the genes targeted, indicating that the RNAi constructs were effective in regulating the expression of the target genes in nonidentical but closely related species. Furthermore, down-regulation of CaFAD2 and CaFAE1 in crambe with the FAD2-FAE1 RNAi vector resulted in even more significant increase in oleic acid level in the seed oil with up to 80% compared to 13% for wild type. The high oleic trait has been stable in subsequent five generations and the GM line grew normally in greenhouse. This work has demonstrated the great potential of producing high oleic oil in crambe, thus contributing to its development into an oil crop platform for industrial oil production.
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