Genomic isolation and transcriptomic differentiation between two ecologically divergent hybridising European forest trees, Populus alba and P. tremula

两种生态上不同的杂交欧洲林木白杨和欧洲山杨之间的基因组分离和转录组分化

• 批准号: NE/E017568/1
• 负责人: Christian Lexer
• 金额: $ 6.71万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FE017568%2F1
• 关键词: Genomic; isolation; transcriptomic; differentiation; between

Barriers to gene flow between divergent populations or species result from selection on divergent phenotypes and from negative genomic interactions in hybrids. Most of our knowledge of the genomic make-up of such barriers to gene exchange stems from a small number of model organisms. The recent sequencing of the Populus genome creates the opportunity to address the genetics of barriers to gene flow in a tree genus with extensive natural hybridization and pronounced interspecific character differences. The applicants have studied the genetics of reproductive isolation and interspecific differences in morphological, yield-related, and ecophysiological traits in several Populus species, including interspecific controlled crosses between the North-American taxa P. trichocarpa and P. deltoides and natural hybrid zones between the European species P. alba and P. tremula. Studies of controlled crosses indicate a heritable basis and complex genetic architecture of interspecific trait differences associated with yield and biomass accumulation. Work on natural hybrid zones indicates that the genetic basis of reproductive isolation in European Populus can be dissected using approaches related to the conceptual frameworks of 'population genomics' as utilized in evolutionary genetics and 'admixture mapping' as utilized in human genetics. The present project is focused on P. alba and P. tremula, two hybridizing, ecologically divergent (flood-plain vs. upland pioneer) species with wide overlapping geographic ranges across Europe. Hybrid zones between these species have formed in multiple locations and are known to contain a high proportion of recombinant backcrosses to P. alba. Thus, hybrid zones or 'admixed populations' offer a powerful tool for the analysis of genetic loci involved in reproductive isolation, a subset of which is expected to be related to ecological divergence. We propose to study intraspecific variation for genomic isolation and its breakdown in three replicate hybrid zones of P. alba and P. tremula in Europe. We plan to use two complementary approaches: (i) a genomic scan using a genome-wide set of codominant mapped molecular genetic markers identified within a previous project, (ii) a candidate gene approach based on the extensive expressed sequence tag (EST) database available for Populus, and on additional candidate genes for ecological divergence identified via microarray-based transcriptomics in a 'tied studentship' associated with this proposal. The genomic scan (i) will allow us to ask what proportion of genetic markers points to linked loci contributing to reproductive isolation in all three of the studied hybrid zones, and what proportion of markers points to intraspecific variation for genomic isolation, either due to variation in linked isolation genes or due to exogeneous selection associated with local differences in the environment. The candidate gene work (ii) will allow us to ask which genomic regions carrying candidate genes for ecological divergence (or genes with great interspecific expression divergence and relation to flooding tolerance; tied studentship) introgress more or less frequently across hybrid zones than expected under neutrality. We will also use our molecular genetic dataset to conduct a replicated 'admixture mapping' genomic scan for loci controlling leaf morphological differences by testing for excess ancestry of mapped markers in plants with extreme leaf traits. The proposed work represents a significant step forward in our long-term goal to understand the genetic basis and origin of inter- and intraspecific barriers to gene flow and trait differences in Populus. This topic is of great relevance not only for ecological & evolutionary genetics, but also for breeding activities in the important 'biomass' crop Populus, and for our ability to predict the conditions under which tree populations are likely to respond successfully in situ to the expected rate of climate change.

不同种群或物种之间的基因流动障碍来自于对不同表型的选择和杂种中的负基因组相互作用。我们对这种基因交换障碍的基因组构成的大部分知识都来自少数模式生物。最近的杨树基因组测序创造了一个机会，以解决广泛的自然杂交和明显的种间性状差异的树属的基因流的遗传障碍。申请人已经研究了几种杨属物种的生殖隔离的遗传学和形态学、产量相关和生理生态学性状的种间差异，包括北美分类群P. alcarpa和P. deltoides之间的种间控制杂交以及欧洲物种P. alba和P. tremula之间的天然杂交区。控制杂交的研究表明，与产量和生物量积累相关的种间性状差异的遗传基础和复杂的遗传结构。自然杂交区的工作表明，在欧洲杨树生殖隔离的遗传基础，可以解剖使用相关的概念框架的“人口基因组学”的进化遗传学和“混合映射”的方法，利用在人类遗传学。本项目的重点是P. alba和P. tremula，这两个杂交的，生态上不同的（洪泛平原与高地先锋）物种，在整个欧洲具有广泛的重叠地理范围。这些物种之间的杂交区已在多个位置形成，并且已知含有高比例的重组回交到白花白杨。因此，混合区或“混合种群”提供了一个强大的工具，用于分析生殖隔离，其中一个子集预计将涉及生态分歧的遗传位点。我们建议研究种内变异的基因组分离和它的崩溃在三个重复的杂交区的欧洲银白杨和P. tremula。我们计划使用两种互补的方法：（i）基因组扫描，使用一组全基因组的共显性映射的分子遗传标记，在以前的项目中确定，（ii）候选基因的方法的基础上广泛表达序列标签（EST）数据库可用于杨树，并通过微阵列为基础的转录组学与此相关的“绑学生”的生态分歧的额外候选基因。基因组扫描（i）将使我们能够了解在所有三个研究的杂交区中，有多大比例的遗传标记指向导致生殖隔离的连锁基因座，以及有多大比例的标记指向基因组隔离的种内变异，无论是由于连锁隔离基因的变异还是由于与环境中的局部差异相关的外源选择。候选基因的工作（ii）将使我们能够问哪些基因组区域携带候选基因的生态分歧（或基因具有很大的种间表达差异和关系到洪水的耐受性;绑学生）渗入更多或更少的频率比预期的跨杂交区下的中立性。我们还将使用我们的分子遗传数据集进行复制的“混合物映射”基因组扫描控制叶形态差异的基因座，通过测试极端叶性状的植物中映射标记的过量祖先。拟议的工作是我们的长期目标，以了解遗传基础和起源的种间和种内的障碍，在杨树基因流和性状差异向前迈出了重要一步。这一主题不仅与生态和进化遗传学有关，而且与重要的“生物量”作物杨树的育种活动有关，也与我们预测树木种群可能在原位成功响应预期气候变化率的条件的能力有关。

项目成果

Biochar mineralization and priming effect on SOM decomposition in two European short rotation coppices

• DOI: 10.1111/gcbb.12219
• 发表时间: 2015-09
• 期刊: GCB Bioenergy
• 作者: M. Ventura;G. Alberti;M. Viger;J. R. Jenkins;C. Girardin;S. Baronti;A. Zaldei;G. Taylor;C. Rumpe