花生是重要的油料作物,花生油中的油酸含量約為36-67%,亞油酸含量約為15-43%。高油酸性狀也是花生育種的重要目標。通過突變脂肪酸脫氫酶FAD編碼基因可以使油酸脫飽和產生亞油酸的過程受阻,從而提高油酸含量。
最近,美國塔斯基吉大學的研究團隊成功利用CRISPR/Cas9技術對花生FAD2進行了突變。
花生中FAD2編碼基因包括ahFAD2A和ahFAD2B,由於花生中存在著FAD2自然突變的種質(油酸含量可達到80%),研究人員選取自然突變的高頻區域作為CRISPR/Cas9編輯的靶標區域,通過原生質體侵染和毛狀根轉化,實現基因編輯。編輯後找到了3個突變基因型,其中ahFAD2A上的兩個突變基因型已存在於天然種質中,ahFAD2B的突變基因型是新生成的變異。
該研究為花生油分改良樹立了很好的參照。
BMC Biotechnology, 29 April 2019
Mutagenesis of FAD2 genes in peanut with CRISPR/Cas9 based gene editing
Author
Mei Yuan, Jun Zhu, Limin Gong, Liangqiong He, Crystal Lee, Suoyi Han, Charles Chen and Guohao He*
*: Tuskegee University, USA
Abstract
Background
Increasing the content of oleic acid in peanut seeds is one of the major goals in peanut breeding due to consumer and industry benefits, such as anti-oxidation and long shelf-life. Homeologous ahFAD2A and ahFAD2B genes encode fatty acid desaturases, which are the key enzymes for converting oleic acid to linoleic acid that oxidizes readily. To date, all high oleic acid peanut varieties result from natural mutations occurred in both genes. A method to induce mutations in the genes of other elite cultivars could speed introgression of this valuable trait. The gene-editing approach utilizing CRISPR/Cas9 technology was employed to induce de novo mutations in the ahFAD2 genesusing peanut protoplasts and hairy root cultures as models.
Results
The hot spot of natural mutation in these genes was selected as the target region. Appropriate sgRNAs were designed and cloned into a CRISPR/Cas9 expression plasmid. As a result of CRISPR/Cas9 activity, three mutations were identified-G448A in ahFAD2A, and 441_442insA and G451T in ahFAD2B. The G448A and 441_442insA mutations are the same as those seen in existing high oleate varieties and the G451T is new mutation. Because natural mutations appear more often in the ahFAD2A gene than in the ahFAD2B gene in subspecies A. hypogaeavar. hypogaea, the mutations induced in ahFAD2B by gene editing may be useful in developing high oleate lines with many genetic backgrounds after validation of oleic acid content in the transformed lines. The appearance of the G448A mutation in ahFAD2A is a further benefit for high oleic acid oil content.
Conclusions
Overall, these results showed that mutations were, for the first time, induced by CRISPR-based gene editing approach in peanut. This research demonstrated the potential application of gene editing for mutagenesis in peanut and suggested that CRISPR/Cas9 technology may beuseful in the peanut breeding programs.
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