C4BREED_Designing C4 breeding strategies using genetic enablers of C4 evolution

C4光合作用被地球上最高产的作物和原生植被所利用。然而，这一复杂性状的分子机制和遗传结构尚不清楚，这阻碍了将这一理想性状引入C3作物的努力。最近，我们和其他人在了解主要物种进化C4光合作用的机制，以及导致完整C4性状的进化轨迹方面取得了重大进展。这一建议建立在这些最新发现的基础上，但结合了我们在C4光合作用方面的专业知识和合成实验进化方法，旨在通过实验重现C4进化的最初步骤。利用这种方法，我们将把对复杂性状分子进化的机制理解转化为一种创新的育种方法，这种方法由进化生物学提供信息，并由合成生物学和基因组编辑实现。为了实现这一目标，我们组建了一个由国际权威人士组成的新团队：宽杂交培育复杂性状（Stich）， DNA编辑技术和合成生物学（Voytas），并将其与C4光合作用（Hibberd和Weber）的专业知识结合起来。我们的具体目的是验证初步光呼吸碳泵的建立降低了二氧化碳补偿点并诱导了原始c4样碳循环的假设；利用C3和C3-C4中间芸苔科种间杂交的力量，通过数量遗传学鉴定C4进化的关键解剖学和生化使能因子；最后，利用基因组编辑和广泛的种内杂交，将C4使能剂引入C3芸苔科植物模型和作物，如油菜。这项工作的结果将包括对一个模型的首次实验测试，该模型预测了复杂的C4性状是如何在60多种情况下独立进化的；首次利用宽交叉、新的测序技术和先进的遗传方法鉴定C4中间体和光合作用的未知成分；以及首次实施基因组编辑和合成生物学，以测试C4中间体和光合作用的成分是否可以在拟南芥和油菜中实施。

C4 photosynthesis is used by the most productive crops and native vegetation on the planet. However, the molecular mechanisms and the genetic architecture underlying this complex trait are poorly understood and this impedes efforts to introduce this desirable trait into C3 crops. Recently, we and others have made significant progress both in understanding the mechanisms that prime species to evolve C4 photosynthesis, and also the evolutionary trajectories that then lead to the full C4 trait. This proposal builds on these recent findings, but combines our expertise in C4 photosynthesis with a synthetic experimental evolution approach that aims to experimentally recapitulate the initial steps towards C4 evolution. Using this approach, we will translate the mechanistic understanding of the molecular evolution of a complex trait into an innovative breeding approach that is informed by evolutionary biology and enabled by synthetic biology and genome editing. To achieve this, we have assembled a new team made up of international authorities on: wide-crossing to breed complex traits (Stich), DNA editing technologies and synthetic biology (Voytas), and combined this with the expertise on C4 photosynthesis (Hibberd and Weber). Our specific aims are to test the hypothesis that establishment of a rudimentary photorespiratory carbon pump reduces the carbon dioxide compensation point and induces a primordial C4-like carbon cycle; to leverage the power of inter-species crosses between C3 and C3-C4 intermediate Brassicaceae species to identify key anatomical and biochemical enablers of C4 evolution by quantitative genetics; and lastly, to employ genome editing and wide intra-species crosses to introduce C4 enablers into C3 Brassicaceaen models and crops, such as oilseed rape.The outcomes of this work will include the first experimental test of a model that predicts how the complex C4 trait evolved independently on over sixty occasions; the first use of wide-crossing, new sequencing technologies and advanced genetic approaches to identify unknown components of C4 intermediacy and photosynthesis; and the first implementation of genome editing and synthetic biology to test whether components of C4 intermediacy and photosynthesis can be implemented in A. thaliana and also oilseed rape.