Deducing the Genomic Footprint and Functional Impact of Chickpea Domestication on Nitrogen Fixation

Pi：Douglas Cook(加州大学戴维斯分校)Copis：Varma Penmetsa(加州大学戴维斯分校)和Eric von Wettberg(佛罗里达国际大学)合作者：Abdullah Kahraman(土耳其哈兰大学)豆类物种是自然和农业生态系统的关键组成部分。它们的重要性在很大程度上源于它们与土壤细菌共生固氮的能力，使它们能够将重要的氮返回土壤环境，并创造出高蛋白含量的种子和饲料。二十年来在模型系统中的分子和基因组研究揭示了启动共生的精致遗传途径的存在，但尽管取得了这些进展，人们基本上对调节自然环境中共生性能的基因知之甚少。该项目下的研究致力于了解豆类作物野生祖先共生性能的演变，以及人类选择在驯化过程中重塑这一潜力的方式。本研究将生态学和种群基因组学与经典的分子遗传学和反向遗传分析相结合，对野生网纹鹰嘴鹰及其驯化的野生种群的功能变异进行了研究。项目成果将以新的方式扩展我们关于共生固氮的知识，并将有助于植物生物学中一种新兴的范式，其中生态学、基因组学和分子生物学的交叉使自然和人类建造环境中的基因功能研究成为可能。重要的是，这些成果应该与基础科学和农业相关。据估计，豆类提供了人类营养氮的30%，而在农业系统中，豆类作物轮作提供了维持土壤肥力的重要手段。尽管豆类作物在固氮方面具有比较优势，但在豆类作物种植过程中经常会添加氮肥，豆类作物通常在谷类作物之后在高残留氮素的情况下种植。这些做法放松了对固氮性状的选择，并通过氮素径流在很大程度上促进了环境退化。更好地了解调节自然和农业环境中固氮的过程，最终将使缓解这些情况的基本战略成为可能。更直接的影响是，该项目的研究人员正在通过参加加州大学戴维斯分校和费尔柴尔德植物园的现有高中科学项目，指导年轻的生物学家代表不足的少数族裔。该项目将为本科生提供实验室科学方面的培训，同时指导他们的学术和专业发展。根据该项目产生的数据和生物资源将通过公共储存库获得，包括国家生物技术信息中心(NCBI)和美国农业部农业研究局的种质资源信息网(GRIN)。还将通过一个具体项目的网站提供信息。

PI: Douglas Cook (University of California - Davis)coPIs: Varma Penmetsa (University of California - Davis) and Eric von Wettberg (Florida International University)Collaborator: Abdullah Kahraman (Harran University, Turkey) Legume species are key components of both natural and agricultural ecosystems. Their importance derives in large part from their capacity for symbiotic nitrogen fixation with soil bacteria, enabling them to return vital nitrogen to the soil environment and to create seed and forage of high protein content. Two decades of molecular and genomic studies in model systems have revealed the presence of exquisite genetic pathways that initiate symbiosis, but despite these advances essentially little is known about genes that regulate symbiotic performance in the natural environment. Research under this project strives to understand the evolution of symbiotic performance in the wild progenitors of legume crops and the ways in which human selection has reshaped this potential during domestication. The research combines ecology and population genomics with classical molecular genetics and reverse genetic assays to deduce the functional consequences of standing variation in wild populations of Cicer reticulatum and its domesticated counterpart Cicer arietinum (chickpea). Project outcomes will expand our knowledge of symbiotic nitrogen fixation in novel ways, and will contribute to an emerging paradigm in plant biology where the intersection of ecology, genomics and molecular biology empowers the study of gene function in natural and human-built environments. Importantly, the outcomes should have relevance to both basic science and to agriculture. Legumes provide an estimated 30% of humankind's nutritional nitrogen, while in agricultural systems crop rotations with legume species provide an important means to maintain soil fertility. Despite legumes' comparative advantage of N-fixation, nitrogen fertilizers are often added during legume cultivation and legumes are often grown under high residual nitrogen following cereal crops. These practices relax selection on nitrogen fixation traits and contribute in a substantial way to environmental degradation through nitrogen runoff. Improved understanding of the processes that regulate N-fixation in natural and agricultural environments will ultimately enable rationale strategies to mitigate these situations. Of more immediate impact, researchers on this project are mentoring under-represented minorities as young biologists by participating in established high school science programs at UC Davis and the Fairchild Botanical Garden. The project will provide training for undergraduate students in laboratory science, while mentoring their academic and professional development. Data and biological resources generated under this project will be available through public repositories, including the National Center for Biotechnology Information (NCBI) and through the Germplasm Resource Information Network (GRIN) of the USDA Agricultural Research Service. Information will also be provided through a project-specific web site.