Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China.
Transgenic Res. 2013 Dec;22(6):1133-42. doi: 10.1007/s11248-013-9717-4. Epub 2013 Jun 6.
Maize (Zea mays spp. mays) is a staple crop for more than 900 million people. The seeds or kernels provide a rich source of calories because ~70% of the weight is carbohydrate, mostly in the form of starch. The content and composition of starch are complex traits controlled by many genes, offering multiple potential targets for intervention. We used a multigene engineering approach combining the overexpression of Bt2, Sh2, Sh1 and GbssIIa (to enhance the activity of sucrose synthase, AGPase and granule-bound starch synthase) with the suppression of SbeI and SbeIIb by RNA interference (to reduce the activity of starch branching enzyme). Maize plants expressing all six genes plus the selectable marker showed a 2.8-7.7% increase in the endosperm starch content and a 37.8-43.7% increase in the proportion of amylose, which was significant compared to untransformed control plants. We also observed improvements in other agronomic traits, such as a 20.1-34.7% increase in 100-grain weight, a 13.9-19.0% increase in ear weight, and larger kernels with a better appearance, presumably reflecting the modified starch structure within the kernels. Our results confirm that multigene engineering applied to the starch biosynthesis pathway can not only modulate the quality and quantity of starch but can also improve starch-dependent agronomic traits.
玉米（Zea mays spp. mays）是超过 9 亿人口的主食作物。其种子或玉米粒是卡路里的丰富来源，因为约 70%的重量是碳水化合物，主要以淀粉的形式存在。淀粉的含量和组成是由许多基因控制的复杂特征，为干预提供了多个潜在目标。我们使用了一种多基因工程方法，结合了 Bt2、Sh2、Sh1 和 GbssIIa 的过表达（以增强蔗糖合酶、AGPase 和颗粒结合淀粉合酶的活性）以及 RNA 干扰对 SbeI 和 SbeIIb 的抑制（以降低淀粉分支酶的活性）。表达所有六个基因加上选择标记的玉米植株，其胚乳淀粉含量增加了 2.8-7.7%，直链淀粉比例增加了 37.8-43.7%，与未转化的对照植株相比有显著差异。我们还观察到其他农艺性状的改善，例如百粒重增加了 20.1-34.7%，穗重增加了 13.9-19.0%，以及更大、外观更好的玉米粒，这可能反映了籽粒内淀粉结构的改变。我们的结果证实，多基因工程应用于淀粉生物合成途径不仅可以调节淀粉的质量和数量，还可以改善依赖淀粉的农艺性状。
