Institute of Crop Sciences (ICS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, China.
China National Rice Research Institute, Hangzhou, China.
Plant Biotechnol J. 2021 May;19(5):937-951. doi: 10.1111/pbi.13519. Epub 2021 Jan 1.
Foods high in amylose content and resistant starch (RS) offer great potential to improve human health and lower the risk of serious noninfectious diseases. Common wheat (Triticum aestivum L.) is a major staple food crop globally. However, the RS contents in the grains of modern wheat varieties are low. Here, we report the generation of high-amylose wheat through targeted mutagenesis of TaSBEIIa in a modern winter wheat cv Zhengmai 7698 (ZM) and a spring wheat cv Bobwhite by CRISPR/Cas9, respectively. We generated a series of transgene-free mutant lines either with partial or triple-null TasbeIIa alleles in ZM and Bobwhite, respectively. Analyses of starch composition, structure and properties revealed that the effects of partial or triple-null alleles were dosage dependent with triple-null lines demonstrated more profound impacts on starch composition, fine structures of amylopectin and physiochemical and nutritional properties. The flours of triple-null lines possessed significantly increased amylose, RS, protein and soluble pentosan contents which benefit human health. Baking quality analyses indicated that the high-amylose flours may be used as additives or for making cookies. Collectively, we successfully modified the starch composition, structure and properties through targeted mutagenesis of TaSBEIIa by CRISPR/Cas9 in both winter and spring wheat varieties and generated transgene-free high-amylose wheat. Our finding provides deep insights on the role of TaSBEIIa in determining starch composition, structure, properties and end-use quality in different genetic backgrounds and improving RS content with multiple breeding and end-use applications in cereal crop species through genome editing for health benefits.
富含直链淀粉和抗性淀粉（RS）的食物对改善人类健康和降低严重非传染性疾病的风险有很大的潜力。普通小麦（Triticum aestivum L.）是全球主要的主食作物。然而，现代小麦品种的 RS 含量较低。在这里，我们分别通过 CRISPR/Cas9 在现代冬小麦品种郑麦 7698（ZM）和春小麦品种 Bobwhite 中靶向突变 TaSBEIIa，生成高直链淀粉小麦。我们分别在 ZM 和 Bobwhite 中生成了一系列具有 TaSBEIIa 部分或三重缺失等位基因的无转基因突变体系。对淀粉组成、结构和性质的分析表明，部分或三重缺失等位基因的效应具有剂量依赖性，三重缺失系对淀粉组成、直链淀粉支链淀粉精细结构以及物理化学和营养性质的影响更为显著。三重缺失系的面粉具有显著增加的直链淀粉、RS、蛋白质和可溶性戊聚糖含量，有利于人类健康。烘焙质量分析表明，高直链淀粉面粉可用作添加剂或制作饼干。总的来说，我们通过 CRISPR/Cas9 成功地对冬小麦和春小麦品种中的 TaSBEIIa 进行了靶向突变，改变了淀粉的组成、结构和性质，并生成了无转基因的高直链淀粉小麦。我们的发现深入了解了 TaSBEIIa 在不同遗传背景下决定淀粉组成、结构、性质和用途品质的作用，并通过基因组编辑提高 RS 含量，为谷物作物的多个育种和用途应用提供了健康益处。
