Identification and Characterization of Single Gene Mutations Causing Heterosis in Tomato

PI：Zachary B.Lippman(冷泉港实验室)合作者：Dani Zamir(希伯来大学)上个世纪，世界主要农作物的农业产量大幅增加，从而为不断增长的人口提供了食物。这主要是由于一个百年前的发现，即杂交不同产量低的玉米自交系品种会在杂交或杂交植株中显著提高产量。这种被称为“杂种优势”的杂交优势，已成为作物育种的基础和研究热点。虽然研究已经揭示了控制杂种优势的重要概括，但负责的单个基因和分子网络仍未确定。这个项目将测试一个新的假设，即单个基因的突变，似乎对植物生长有害，当杂交回正常的非突变植物时，可以导致杂种优势。在“突变杂种”中产生的部分基因活动导致了一种新的生长状态，这种生长状态通过一种称为“剂量”的遗传现象对产量有利。对番茄的初步研究已经确定了多个能增加果实产量的突变杂交种。基于这些发现，该项目的目标将是：i)寻找更多与正常植株杂交时表现出杂种优势的番茄突变体；ii)表征生长的变化(例如分枝数、花朵产量)，这些变化是先前确定的两个突变杂交种的杂种优势的基础；以及iii)研究突变杂交种中所有番茄基因活性的新变化。与以前的研究不同，该项目将能够将单个基因的杂种优势效应与生长的特定变化和基因活动的相关变化联系起来。这些新知识可以被用来识别其他作物物种的杂种优势基因。为了向公众推广关于杂种优势的教育推广和这个项目的原理，已经开发了一个关于植物育种和粮食生产的教学计划。具体地说，已经为纽约皇后区一所学生人数不足的小学设计了一堂由三部分组成的课程，解释植物产生花朵、水果和种子的过程。来自多种作物的活植物将被用来说明当植物从造叶转向造花时，生长发生的戏剧性变化。讨论部分将强调环境如何与植物相互作用以刺激花卉和水果生产，以及植物育种者如何利用这些知识开发新的作物品种。预计这一外展项目将成为未来针对纽约市更多学校的项目的典范。最后，在该项目中产生的所有数据将通过茄科基因组学网络(http://sgn.cornell.edu/).)公开提供此外，来自突变杂交种的种子可以从冷泉港实验室(http://www.cshl.edu/public/SCIENCE/lippman.html)和番茄遗传资源中心(http://tgrc.ucdavis.edu/).)获得

PI: Zachary B. Lippman (Cold Spring Harbor Laboratory)Collaborator: Dani Zamir (Hebrew University)The agricultural yields of the world's major crop plants have increased significantly in the last century, thus providing food for an ever-growing population. This was made possible primarily through the century-old discovery that crossing different poor-yielding inbred varieties of corn causes a remarkable increase in yield among the inter-crossed, or hybrid, plants. Such hybrid vigor, termed "heterosis", has since become a foundation for crop breeding and a focus of intense research. While studies have revealed important generalizations about what controls heterosis, the individual genes and molecular networks responsible have still not been identified. This project will test a new hypothesis, namely that a mutation in a single gene, which is seemingly detrimental to plant growth, can cause heterosis when hybridized back to a normal non-mutant plant. The resulting partial gene activity in the "mutant hybrid" results in a new state of growth that is beneficial to yield through a genetic phenomenon called "dosage". Preliminary research in tomato has already identified multiple mutant hybrids that increase fruit production. Based on these findings, the goals of this project will be to: i) search for additional tomato mutants that show heterosis when hybridized with normal plants, ii) characterize the changes in growth (e.g. branch number, flower production) that are the basis for heterosis in two previously identified mutant hybrids, and iii) study novel changes in the activity of all tomato genes in mutant hybrids. Unlike previous studies, this project will be able to link heterotic effects of a single gene with specific changes in growth and relevant changes in gene activity. This new knowledge can then be harnessed to identify genes causing heterosis in other crop species.To promote educational outreach about heterosis and the principles of this project to the general public, a teaching program about plant breeding and food production has been developed. Specifically, a three-part lesson explaining the processes by which plants make flowers, fruits, and seeds has been developed for an elementary school with an underrepresented student population in Queens, New York. Live plants from multiple crops will be used to illustrate the dramatic changes in growth that occur as plants switch from making leaves to making flowers. Discussion sections will emphasize how the environment interacts with plants to stimulate flower and fruit production, and how plant breeders leverage this knowledge to develop new crop varieties. It is anticipated that this outreach project will serve as a model for future programs that will target additional schools in New York City. Finally, all data generated in this project will be made publicly available through the Solanaceae Genomics Network (http://sgn.cornell.edu/). In addition, seeds from mutant hybrids can be requested from Cold Spring Harbor Laboratory (http://www.cshl.edu/public/SCIENCE/lippman.html) and from the Tomato Genetics Resource Center (http://tgrc.ucdavis.edu/).