Elucidating the Gene Networks Controlling Branch Angle and the Directional Growth of Lateral Meristems in Trees

该项目将揭示支持顶端控制如何影响树木分支生长的基因和基因网络。 对植物生物学这一知之甚少但又十分基本的方面的解读，将有助于阐明树种的进化，并对森林生态学和生长动态产生重要影响。 从实际意义上讲，这项工作将有助于通过开发适合高密度种植的树种来改变未来的果园和树木种植园-实现类似于过去半个世纪谷物作物所实现的生产力提高。这些改良品种的商业化种植将导致更有效的土地空间利用，减少化学投入，提高行业盈利能力和可持续性。 为了整合教育和研究并扩大参与，该项目将为代表性不足的少数群体的本科生和高中生提供植物基因组学方面的研究培训。 此外，该项目将组织和举办一系列关于植物结构和生物技术解决方案的讲习班，向种植者和农业行业人员介绍生物技术为树木作物带来的具体好处。最后，该项目将为从事树木和其他园艺作物研究的科学家开发和举办关于新的基于序列的作图和基因鉴定方法的短期课程，该方法使用汇集的基因组或pnome。 公众可通过NCBI（http：//www.example.com）Short Reads Archive数据库和/或蔷薇科基因组数据库（http：//www.rosaceae.org/）访问本项目生成的所有数据。www.ncbi.nlm.nih.gov树木可以采用各种各样的建筑形式。建筑可塑性在森林生态系统、农业和景观美学中起着重要作用。树的结构是许多发育性状的结果，包括分枝模式、分支数量、分支长度和分支角度。这些性状在很大程度上是两个关键发育过程的功能：顶端优势和顶端控制。 顶端优势是一个很好理解的过程，抑制侧芽生长通过信号发出的茎尖。深入的研究揭示了在草本植物如拟南芥和豌豆中起作用的信号和潜在的分子机制。相反，顶端控制是指木本植物在连续多年的生长和发育过程中，顶端对树木整体结构的影响。虽然从生理学的角度已经取得了一些进展，顶端控制的遗传和分子机制在很大程度上是未知的。 该项目的总体目标是详细了解树木如何采用特定的建筑形式，特别是关于侧分支角度和方向生长的顶端控制。 利用基因组规模的研究来阐明关键的基因网络和分子途径，再加上创新的全树成像技术，这将使非破坏性的结构表型，该项目将解决以下问题：1）什么基因表达网络区分茎顶端分生组织从侧分生组织？当侧枝分生组织转变为顶端分生组织时，发生了什么变化？这些表达网络在分支角度突变体中是如何改变的，包括柱状/柱状树形和垂枝型？2)桃和苹果树的这些突变体的遗传和分子基础是什么？变异基因的身份是什么？3)对于已识别的基因，它们与哪些蛋白质-蛋白质相互作用网络相关？它们通过哪些途径对树木形态产生影响？

This project will uncover genes and gene networks that underpin how apical control influences branch growth in trees. Deciphering this poorly understood yet fundamental aspect of plant biology will shed light on the evolution of tree species and have important implications for forest ecology and growth dynamics. In a practical sense, the work will help transform the orchards and tree plantations of the future through the development of tree varieties suitable for high density planting- achieving productivity improvements analogous to those accomplished for cereal crops over the past half century. Commercial planting of these improved varieties will lead to more efficient land space utilization, reduction of chemical inputs, and increased industry profitability and sustainability. To integrate education and research and broaden participation, the project will provide research training in plant genomics for undergraduate and high school students from underrepresented minority groups. In addition, the project will organize and hold a series of workshops on plant architecture and biotechnology solutions that will educate growers and agricultural industry personnel about specific benefits biotechnology has to offer tree crops. Finally, the project will develop and hold short courses on a novel sequence-based mapping and gene identification method using pooled genomes or pnomes for fellow scientists working on trees and other horticultural crops. All data generated in this project will be accessible to the public through the NCBI (http://www.ncbi.nlm.nih.gov) Short Reads Archive databases and/or the Genome Database for Rosaceae (http://www.rosaceae.org/). Trees can adopt a wide variety of architectural forms. Architectural plasticity plays important roles in forest ecosystems, agriculture, and landscape aesthetics. Tree architecture is a consequence of numerous developmental traits that include branching pattern, branch number, branch length, and branch angle. These traits are largely a function of two key developmental processes: apical dominance and apical control. Apical dominance is a well understood process that inhibits lateral bud outgrowth through signals emanating from the shoot apex. Intensive studies have revealed the signals and the underlying molecular mechanisms that operate in herbaceous plants such as Arabidopsis and pea. In contrast, apical control is the process by which the apex influences the overall tree structure upon successive years of growth and development in woody species. Although some progress has been made from a physiological perspective, the genetic and molecular mechanisms of apical control are largely unknown. The overarching goal of the project is to develop detailed knowledge about how trees adopt specific architectural forms, specifically with regard to apical control of the lateral branch angle and directional growth. Using a combination of genome-scale studies to elucidate key gene networks and molecular pathways coupled with innovative whole tree imaging technologies that will enable non-destructive structural phenotyping, the project will address the following questions: 1) What gene expression networks differentiate the shoot apical meristem from lateral meristems? What changes take place when a lateral shoot meristem transitions to becoming the apical meristem? How are these expression networks altered in branch angle mutants including pillar/columnar tree forms and weeping types? 2) What is the genetic and molecular basis for these mutant tree forms in peach and apple? What are the identities of the mutated genes? 3) With regard to the identified genes, what protein-protein interaction networks are they associated with? Through which pathways do they exert their effects on tree form?