高粱籽粒蛋白的主要成分是醇溶蛋白，由於缺乏必須胺基酸（賴氨酸）且難消化，影響了高粱籽粒在動物飼料和食品上的應用價值。近日，美國內布拉斯加-林肯分校的研究團隊利用 CRISPR/Cas9基因編輯技術對高粱醇溶蛋白基因家族進行編輯，提高了高粱籽粒的品質。
醇溶蛋白的主要成分是α-醇溶蛋白，它是由具有高度相似性的k1C基因家族編碼。研究人員利用CRISPR/Cas9系統，在α-醇溶蛋白保守的內質網信號肽編碼區域設計sgRNA。通過單個gRNA介導的CRISPR/Cas9系統成功地誘導了k1C基因家族成員的廣泛突變，進而降低了籽粒中α-醇溶蛋白的含量，提高了賴氨酸含量和穀物消化度。
該研究為培育高賴氨酸、高消化性非轉基因高粱品種提供了重要思路。
Plant Physiology, 20 June 2018
Editing of an alpha-kafirin gene family increases digestibility and protein quality in sorghum
Author
Aixia Li, Shangang Jia, Abou Yobi……Ruthie Angelovici, Tom E. Clemente, David R. Holding*
*: Department of Agronomy and Horticulture and Center for PlantScience Innovation, University of Nebraska-Lincoln, USA
Abstract
Kafirins are the major storage proteins in sorghum (Sorghum bicolor) grains and form protein bodies with poor digestibility. Since kafirins are devoid of the essential amino acid lysine, they also impart poor protein quality to the kernel. The α-kafirins, which make up most of the total kafirins, are largely encoded by the k1C family of highly similar genes. We used a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene editing approach to target the k1C genes to create variants with reduced kafirin levels and improved protein quality and digestibility. A single guide RNA (sgRNA) was designed to introduce mutations in a conserved region encoding the endoplasmic reticulum signal peptide of α-kafirins. Sequencing of kafirin PCR products revealed extensive edits in 25 of 26 events in one or multiple k1C family members. T1 and T2 seeds showed reduced α-kafirin levels, and selected T2 events showed significantly increased grain protein digestibility and lysine content. Thus, a single consensus sgRNA carrying target sequence mismatches is sufficient for extensive editing of all k1C genes. The resulting quality improvements can be rapidly deployed for breeding and generation of transgene-free, improved cultivars of sorghum, a major crop worldwide.
查看全文請戳下方「閱讀原文」！
相關閱讀：
操控硫同化過程，提高飼用玉米營養品質
培育優質蛋白玉米的新基因o16
杜邦先鋒公司建立高粱高效的遺傳轉化體系