Homologous electron transport components fail to increase fatty acid hydroxylation in transgenic Arabidopsis thaliana [v2; ref status: indexed, http://f1000r.es/2a3]
Ricinoleic acid, a hydroxylated fatty acid (HFA) present in castor (Ricinus communis) seeds, is an important industrial commodity used in products ranging from inks and paints to polymers and fuels. However, due to the deadly toxin ricin and allergens also present in castor, it would be advantageous...
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F1000 Research Ltd
2013-11-01
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| Online Access: | http://f1000research.com/articles/2-203/v2 |
| _version_ | 1818878708571701248 |
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| author | Laura L. Wayne John Browse |
| author_facet | Laura L. Wayne John Browse |
| author_sort | Laura L. Wayne |
| collection | DOAJ |
| description | Ricinoleic acid, a hydroxylated fatty acid (HFA) present in castor (Ricinus communis) seeds, is an important industrial commodity used in products ranging from inks and paints to polymers and fuels. However, due to the deadly toxin ricin and allergens also present in castor, it would be advantageous to produce ricinoleic acid in a different agricultural crop. Unfortunately, repeated efforts at heterologous expression of the castor fatty acid hydroxylase (RcFAH12) in the model plant Arabidopsis thaliana have produced only 17-19% HFA in the seed triacylglycerols (TAG), whereas castor seeds accumulate up to 90% ricinoleic acid in the endosperm TAG. RcFAH12 requires an electron supply from NADH:cytochrome b5 reductase (CBR1) and cytochrome b5 (Cb5) to synthesize ricinoleic acid. Previously, our laboratory found a mutation in the Arabidopsis CBR1 gene, cbr1-1, that caused an 85% decrease in HFA levels in the RcFAH12 Arabidopsis line. These results raise the possibility that electron supply to the heterologous RcFAH12 may limit the production of HFA. Therefore, we hypothesized that by heterologously expressing RcCb5, the reductant supply to RcFAH12 would be improved and lead to increased HFA accumulation in Arabidopsis seeds. Contrary to this proposal, heterologous expression of the top three RcCb5 candidates did not increase HFA accumulation. Furthermore, coexpression of RcCBR1 and RcCb5 in RcFAH12 Arabidopsis also did not increase in HFA levels compared to the parental lines. These results demonstrate that the Arabidopsis electron transfer system is supplying sufficient reductant to RcFAH12 and that there must be other bottlenecks limiting the accumulation of HFA. |
| first_indexed | 2024-12-19T14:18:29Z |
| format | Article |
| id | doaj.art-3125faf4566348e98e368d8bee82ae8e |
| institution | Directory Open Access Journal |
| issn | 2046-1402 |
| language | English |
| last_indexed | 2024-12-19T14:18:29Z |
| publishDate | 2013-11-01 |
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| spelling | doaj.art-3125faf4566348e98e368d8bee82ae8e2022-12-21T20:17:53ZengF1000 Research LtdF1000Research2046-14022013-11-01210.12688/f1000research.2-203.v22955Homologous electron transport components fail to increase fatty acid hydroxylation in transgenic Arabidopsis thaliana [v2; ref status: indexed, http://f1000r.es/2a3]Laura L. Wayne0John Browse1Dow AgroSciences, Indianapolis, IN 46268, USAInstitute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340, USARicinoleic acid, a hydroxylated fatty acid (HFA) present in castor (Ricinus communis) seeds, is an important industrial commodity used in products ranging from inks and paints to polymers and fuels. However, due to the deadly toxin ricin and allergens also present in castor, it would be advantageous to produce ricinoleic acid in a different agricultural crop. Unfortunately, repeated efforts at heterologous expression of the castor fatty acid hydroxylase (RcFAH12) in the model plant Arabidopsis thaliana have produced only 17-19% HFA in the seed triacylglycerols (TAG), whereas castor seeds accumulate up to 90% ricinoleic acid in the endosperm TAG. RcFAH12 requires an electron supply from NADH:cytochrome b5 reductase (CBR1) and cytochrome b5 (Cb5) to synthesize ricinoleic acid. Previously, our laboratory found a mutation in the Arabidopsis CBR1 gene, cbr1-1, that caused an 85% decrease in HFA levels in the RcFAH12 Arabidopsis line. These results raise the possibility that electron supply to the heterologous RcFAH12 may limit the production of HFA. Therefore, we hypothesized that by heterologously expressing RcCb5, the reductant supply to RcFAH12 would be improved and lead to increased HFA accumulation in Arabidopsis seeds. Contrary to this proposal, heterologous expression of the top three RcCb5 candidates did not increase HFA accumulation. Furthermore, coexpression of RcCBR1 and RcCb5 in RcFAH12 Arabidopsis also did not increase in HFA levels compared to the parental lines. These results demonstrate that the Arabidopsis electron transfer system is supplying sufficient reductant to RcFAH12 and that there must be other bottlenecks limiting the accumulation of HFA.http://f1000research.com/articles/2-203/v2Plant Cell BiologyPlant Genetics & Gene Expression |
| spellingShingle | Laura L. Wayne John Browse Homologous electron transport components fail to increase fatty acid hydroxylation in transgenic Arabidopsis thaliana [v2; ref status: indexed, http://f1000r.es/2a3] F1000Research Plant Cell Biology Plant Genetics & Gene Expression |
| title | Homologous electron transport components fail to increase fatty acid hydroxylation in transgenic Arabidopsis thaliana [v2; ref status: indexed, http://f1000r.es/2a3] |
| title_full | Homologous electron transport components fail to increase fatty acid hydroxylation in transgenic Arabidopsis thaliana [v2; ref status: indexed, http://f1000r.es/2a3] |
| title_fullStr | Homologous electron transport components fail to increase fatty acid hydroxylation in transgenic Arabidopsis thaliana [v2; ref status: indexed, http://f1000r.es/2a3] |
| title_full_unstemmed | Homologous electron transport components fail to increase fatty acid hydroxylation in transgenic Arabidopsis thaliana [v2; ref status: indexed, http://f1000r.es/2a3] |
| title_short | Homologous electron transport components fail to increase fatty acid hydroxylation in transgenic Arabidopsis thaliana [v2; ref status: indexed, http://f1000r.es/2a3] |
| title_sort | homologous electron transport components fail to increase fatty acid hydroxylation in transgenic arabidopsis thaliana v2 ref status indexed http f1000r es 2a3 |
| topic | Plant Cell Biology Plant Genetics & Gene Expression |
| url | http://f1000research.com/articles/2-203/v2 |
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