Genetic reconfigurations en route to a holoparasitic lifestyle in plants

萝卜科(萝卜科)的寄生植物从其他植物那里窃取水分和养分。世界上最有问题的寄生杂草之一是雀麦(Orobanche s.l.)以及独脚金(Striga)，它们攻击重要的谷物和蔬菜作物的根。了解影响萝卜科内寄生虫进化的分子进化力量和制约因素将有助于我们制定更有效和可持续的害虫防治程序。这项研究的目的是确定与萝卜科植物从自养生活方式向全寄生生活方式的转变相关的共性以及适应性和非适应性遗传重组。拟议的研究计划利用了高粱家族独特的、自然的遗传多样性，包括完整的营养谱，包括非寄生虫、各种特化的半寄生虫和多次独立进化的全寄生。我们将测试在向全寄生的转变之前或之后是否以及哪些基因变化，以及这些重新配置是否以可预测的顺序发生。主要目的是弄清寄生虫基因分子进化转变的性质和方向。我们将检查它们基因突变率的变化。我们将测试寄生虫基因的替换率变化是否可以通过修改的转录本水平来机械地解释，这些转录本水平是由于与营养专化程度相关的选择压力的改变造成的。我们将使用定性和定量的RNA和DNA测序来比较几个自养和异养萝卜科植物的基因组和基因表达。我们将使用现有的和设计新的概率模型来测试我们的研究假设，在一个融合了基因和表型信息的统一计算框架中。这项研究将首次测试密切相关的寄生植物遗传图谱的变化与潜在的分子进化力量之间的相互作用如何作为宏观进化变化的燃料-反之亦然。成熟的萝卜科模式系统与最先进的分子进化方法相结合，为开发与植物营养专门化相关的遗传变化解释模型提供了理想的工具。我们的研究目标集中在有关萝卜科遗传学的关键问题上，同时解决尚未解决的植物分子速率变异问题。因此，我们的工作将有助于揭开植物向寄生转变的原因和后果，并确定其潜在的机制。进化生物学中的比较生物计算方法将进一步发展基因组和表型变化的影响的通用解释模型，这将影响生命科学的许多分支的研究领域。

Parasitic plants of the broomrape family (Orobanchaceae) steal both water and nutrients from other plants. Amongst the world's most problematic parasitic weeds are broomrapes (Orobanche s.l.) and witchweeds (Striga), which attack the roots of important cereals and vegetable crops. Fundamental knowledge of the molecular evolutionary forces and constraints influencing the evolution of parasitism within Orobanchaceae would help us to develop more effective and sustainable pest control procedures. The goal of this research is to identify commonalities as well as adaptive and nonadaptive genetic reconfigurations that are associated with the transition from an autotrophic to a holoparasitic way of life within the Orobanchaceae. The proposed research program exploits the unique, natural genetic diversity of the broomrape family, which comprises the full trophic spectrum including nonparasites, hemiparasites of various specializations and holoparasites that have evolved multiple times independently. We will test whether and which genetic changes precede or follow the transition to holoparasitism and if these reconfigurations occur in a predictable order. A primary aim is to disentangle the nature and direction of molecular evolutionary shifts in the genes of the parasites. We will examine changes in the mutational rates of their genes. We will test whether substitution rate shifts in the genes of the parasites can be explained mechanistically by the modified transcript levels due to altered selection pressures relating to the degree of trophic specialization. We will use qualitative and quantitative RNA and DNA sequencing to compare the gene sets and gene expression between several autotrophic and heterotrophic Orobanchaceae. We will employ existing and devise novel probabilistic models to test our research hypotheses in a unified computational framework that fuses genotypic and phenotypic information. This study will be the first to test how the interplay between changes in the genetic profile of closely related parasitic plants and the underlying molecular evolutionary forces act as fuel for macroevolutionary change - and vice versa. The well-developed Orobanchaceae model system in combination with state-of-the-art molecular evolutionary methods provides the ideal tool to develop an explanatory model for the genetic changes associated with trophic specialization in plants. Our research objectives focus on key questions concerning the genetics of Orobanchaceae and, at the same time, address unresolved issues of molecular rate variation in plants. Thus, our work will contribute towards unraveling the causes and consequences of the transition to parasitism in plants and identifying its underlying mechanisms. Comparative biocomputational approaches in evolutionary biology will further the development of a generalized explanatory model of the effects of genomic and phenotypic shifts, which will impact research areas in many branches of the life sciences.