Dow AgroSciences, LLC, 9330 Zionsville Rd, Indianapolis, IN, 46268, USA.
Current address: Purdue University College of Pharmacy, 575 Stadium Mall Drive, West Lafayette, IN, 47907, USA.
BMC Plant Biol. 2018 Jan 15;18(1):14. doi: 10.1186/s12870-018-1227-3.
Availability of well characterized maize regulatory elements for gene expression in a variety of tissues and developmental stages provides effective alternatives for single and multigene transgenic concepts. We studied the expression of the herbicide tolerance gene aryloxyalkanoate dioxygenase (aad-1) driven by seven different regulatory element construct designs including the ubiquitin promoters of maize and rice, the actin promoters of melon and rice, three different versions of the Sugarcane Bacilliform Badnavirus promoters in association with other regulatory elements of gene expression.
Gene expression of aad-1 was characterized at the transcript and protein levels in a collection of maize tissues and developmental stages. Protein activity against its target herbicide was characterized by herbicide dosage response. Although differences in transcript and protein accumulation were observed among the different constructs tested, all events were tolerant to commercially relevant rates of quizalafop-P-ethyl compared to non-traited maize under greenhouse conditions.
The data reported demonstrate how different regulatory elements affect transcript and protein accumulation and how these molecular characteristics translate into the level of herbicide tolerance. The level of transcript detected did not reflect the amount of protein quantified in a particular tissue since protein accumulation may be influenced not only by levels of transcript produced but also by translation rate, post-translational regulation mechanisms and protein stability. The amount of AAD-1 enzyme produced with all constructs tested showed sufficient enzymatic activity to detoxify the herbicide and prevent most herbicidal damage at field-relevant levels without having a negative effect on plant health.
Distinctive profiles of aad-1 transcript and protein accumulation were observed when different regulatory elements were utilized in the constructs under study. The ZmUbi and the SCBV constructs showed the most consistent robust tolerance, while the melon actin construct provided the lowest level of tolerance compared to the other regulatory elements used in this study. These data provide insights into the effects of differing levels of gene expression and how these molecular characteristics translate into the level of herbicide tolerance. Furthermore, these data provide valuable information to optimize future designs of single and multiple gene constructs for maize research and crop improvement.
具有良好特征的玉米调控元件可用于各种组织和发育阶段的基因表达，为单基因和多基因转基因概念提供了有效的替代方案。我们研究了七种不同调控元件构建体设计驱动的除草剂耐受基因芳氧基烷酸双加氧酶（aad-1）的表达，这些构建体设计包括玉米和水稻的泛素启动子、甜瓜和水稻的肌动蛋白启动子、与其他基因表达调控元件相关的三种不同版本的甘蔗束状病毒启动子。
aad-1 的基因表达在一系列玉米组织和发育阶段的转录和蛋白质水平上进行了表征。通过除草剂剂量反应来表征其靶标除草剂的蛋白质活性。尽管在测试的不同构建体之间观察到转录本和蛋白质积累的差异，但与温室条件下未经修饰的玉米相比，所有事件都耐受商业上相关的氯氟吡氧乙酸乙酯剂量。
报告的数据表明不同的调控元件如何影响转录本和蛋白质积累，以及这些分子特征如何转化为除草剂耐受水平。在特定组织中检测到的转录本水平并不能反映定量的蛋白质量，因为蛋白质积累不仅受产生的转录本水平的影响，还受翻译率、翻译后调节机制和蛋白质稳定性的影响。用所有测试的构建体产生的 AAD-1 酶具有足够的酶活性来解毒除草剂，并在没有对植物健康产生负面影响的情况下防止田间相关水平的大多数除草剂损伤。
当在研究中的构建体中利用不同的调控元件时，观察到 aad-1 转录本和蛋白质积累的独特特征。ZmUbi 和 SCBV 构建体表现出最一致的稳健耐受性，而与本研究中使用的其他调控元件相比，甜瓜肌动蛋白构建体提供的耐受性最低。这些数据提供了对不同基因表达水平的影响的深入了解，以及这些分子特征如何转化为除草剂耐受水平。此外，这些数据为优化未来用于玉米研究和作物改良的单基因和多基因构建体的设计提供了有价值的信息。
