Chang Megan M, Nail Danielle Allery, Kazic Toni, Simmons Susan J, Stapleton Ann E
Department of Biology and Marine Biology, University of North Carolina Wilmington, NC 28403.
Science Department, Green Hope High School, Cary, NC 27519.
G3 (Bethesda). 2018 May 4;8(5):1481-1496. doi: 10.1534/g3.118.200123.
Crop improvement must accelerate to feed an increasing human population in the face of environmental changes. Including anticipated climatic changes with genetic architecture in breeding programs could better optimize improvement strategies. Combinations of drought and nitrogen limitation already occur world-wide. We therefore analyzed the genetic architecture underlying the response of to combinations of water and nitrogen stresses. Recombinant inbreds were subjected to nine combinations of the two stresses using an optimized response surface design, and their growth was measured. Three-dimensional response surfaces were fit globally and to each polymorphic allele to determine which genetic markers were associated with different response surfaces. Three quantitative trait loci that produced nonlinear surfaces were mapped. To better understand the physiology of the response, we developed a model that reproduced the shapes of the surfaces, their most characteristic feature. The model contains two components that each combine the nitrogen and water inputs. The relative weighting of the two components and the inputs is governed by five parameters, and each QTL affects all five parameters.We estimated the model's parameter values for the experimental surfaces using a mesh of points that covered the surfaces' most distinctive regions. Surfaces computed using these values reproduced the experimental surfaces well, as judged by three different criteria at the mesh points. The modeling and shape comparison techniques used here can be extended to other complex, high-dimensional, nonlinear phenotypes. We encourage the application of our findings and methods to experiments that mix crop protection measures, stresses, or both, on elite and landrace germplasm.
面对环境变化，作物改良必须加速，以养活不断增长的人口。在育种计划中纳入预期的气候变化及遗传结构，能够更好地优化改良策略。干旱和氮素限制的组合已在全球范围内出现。因此，我们分析了作物对水分和氮素胁迫组合响应的遗传结构。利用优化的响应面设计，让重组自交系经受这两种胁迫的九种组合，并测量它们的生长情况。对三维响应面进行全局拟合，并对每个多态性等位基因进行拟合，以确定哪些遗传标记与不同的响应面相关联。定位了三个产生非线性表面的数量性状位点。为了更好地理解这种响应的生理学机制，我们开发了一个模型，该模型再现了表面的形状，这是它们最显著的特征。该模型包含两个组件，每个组件都结合了氮和水的输入。两个组件和输入的相对权重由五个参数控制，每个数量性状位点影响所有五个参数。我们使用覆盖表面最独特区域的点网格，估计了实验表面模型的参数值。根据网格点处的三个不同标准判断，使用这些值计算出的表面很好地再现了实验表面。这里使用的建模和形状比较技术可以扩展到其他复杂、高维、非线性表型。我们鼓励将我们的研究结果和方法应用于在优良和地方品种种质上混合作物保护措施、胁迫或两者的实验。
