| 中文摘要 |
基因組定點編輯技術在近十年來受到科學家的重視。除了似轉錄活化蛋白效應子核酸酶（Transcription activator-like effector nucleases, TALEN）及鋅指核酸酶（zincfinger nuclease, ZFN）常用的基因組編輯工具外，群聚且規律性間隔的短廻文重複序列（clustered regularly interspaced short palindromic repeats, CRISPR）/CRISPR關聯蛋白質9（CRISPR-associated protein 9, Cas9）是更快速且便宜的新選項。CRISPR/Cas9源自於原核生物的第二型CRISPR/Cas防禦系統，經人為改良後，核酸內切酶Cas9與單一導引RNA（single-guide RNA, sgRNA）結合所形成的複合物，能辨識目標基因組DNA上的前間隔序列鄰近構形（protospacer adjacent motif, PAM），使目標基因組DNA產生雙股斷裂（doublestrand break, DSB），再經過非同源染色體末端連接（non-homologous end-joining, NHEJ）或同源重組（homologous recombination），可達到基因編輯的效果。目前已透過CRISPR/Cas9改變多項農作物性狀，如花色調控、延長櫥架壽命、抗殺草劑、提升抗逆境能力、增加抗病性等。利用CRISPR/Cas9創造的作物透過孟德爾遺傳分離後，不含其他生物的外源基因，因此不受基因改造法規的限制，成為科學界研究與開發的最新利器。
In the recent decade, scientists put more attention on genome site-specific editing technologies, such as transcription activator-like effector nucleases (TALEN) and zinc finger nuclease (ZFN). Recently, a new method based on bacterial clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas9) type II prokaryotic adaptive immune system has become a novel tool for genome site-specific editing technology. An engineered single-guide RNA (sgRNA) that specifies a targeted sequence will form a complex with the endonuclease Cas9 to recognize the protospacer adjacent motif (PAM) near the target sequence. Then the target sequence is edited by non-homologous end-joining (NHEJ) or homologous recombination. So far, several agricultural traits has been manipulated by CRISPR/Cas9, including change of flower color, extension of shelf-life, development of herbicide-resistant crops, and improvement of stress- and disease-resistance of crops. After Mendelian segregation the CRISPR/Cas9-edited plant without any foreign genes is not classified as a genetic modified organism. Due to the ease of operation and less regulation of genetically modified organisms, CRISPR/Cas9 becomes a powerful tool to for plant breeders and researchers. |
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