Identification and Characterization of Single Gene Mutations Causing Heterosis in Tomato

PI：Zachary B。李普曼（冷泉港实验室）合作者：达尼·扎米尔（希伯来大学）在上个世纪，世界主要农作物的农业产量显著增加，从而为不断增长的人口提供了食物。这主要是由于一个世纪的发现，即杂交不同的低产玉米自交系品种会导致杂交或杂交植物的产量显着增加。这种杂种优势，被称为“杂种优势”，已成为作物育种的基础和深入研究的焦点。 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然没有被确定。该项目将测试一个新的假设，即在一个单一的基因突变，这似乎是有害的植物生长，可以导致杂种优势时，杂交回正常的非突变植物。在“突变杂种”中产生的部分基因活性导致一种新的生长状态，这种生长状态通过称为“剂量”的遗传现象有利于产量。对番茄的初步研究已经确定了多种增加果实产量的突变杂交种。基于这些发现，本项目的目标将是：i）寻找与正常植物杂交时显示出杂种优势的其他番茄突变体，ii）表征生长变化（例如分支数量、花产量），这些变化是两种先前鉴定的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性的相关变化联系起来。这些新的知识可以被用来鉴定其他作物物种中引起杂种优势的基因。为了向公众推广杂种优势和该项目的原理，开发了一个关于植物育种和食品生产的教学计划。具体来说，一个由三部分组成的课程，解释了植物使花，水果和种子的过程已经开发了一个小学与代表性不足的学生人口在皇后区，纽约。将使用多种作物的活体植物来说明当植物从长叶转向开花时生长发生的巨大变化。讨论部分将强调环境如何与植物相互作用，以刺激花卉和水果的生产，以及植物育种家如何利用这些知识来开发新的作物品种。预计这一推广项目将成为今后针对纽约市其他学校的方案的典范。最后，该项目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，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/）索取来自突变杂种的种子。

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/).