Natural Variation in Meiotic Recombination in Maize.

本项目的目的是研究玉米减数分裂重组的自然多样性。减数分裂重组是遗传变异的主要来源，负责在后代中产生新的基因组合。重组在真核生物进化中的作用以及调节重组频率的机制是现代生物学的核心问题。然而，虽然对重组的机制方面了解很多，包括已经鉴定的大量减数分裂蛋白，但调节减数分裂重组率的因素仍然知之甚少。为了了解减数分裂重组途径的定量调控，必须首先检查重组率的变化程度。本研究利用一组27个不同的自交系，探索了全球（整个基因组）重组率的变化，这些自交系捕获了玉米80%以上的等位基因多样性。最近发展的染色体绘制技术被用来测量每条玉米染色体上的交叉数目。此外，对标记两种主要重组中间体的两种重组蛋白RAD51和MLH1的染色体病灶进行了定量分析。对玉米关键重组基因的自然多样性也进行了探讨。这组不同的玉米自交系被用来检查这些基因的DNA序列的变化以及它们的表达水平。在该项目范围内产生的数据将为未来的研究奠定基础，以确定影响玉米减数分裂重组频率的qtl，并检查重组频率变异与候选重组基因变异之间的关系。最终，这项研究将有助于阐明调节植物减数分裂重组率的机制。了解重组的机制是植物育种的核心问题，因为重组会产生新的遗传变异，育种者会对这些变异进行选择。植物育种者可以利用高重组系来减少性状渗入过程中的连锁阻力，获得代表新的理想基因组合的重组体，使用更小的育种群体，并加快育种周期。大学生和高中生的外联和培训是该项目的重要组成部分。这些活动被整合到康奈尔/博伊斯汤普森研究所的植物基因组外展计划中（http://outreach-pgrp.cornell.edu）。该计划成立于2003年，促进了由美国国家科学基金会植物基因组研究计划资助的大量不同的推广工作。该项目将参与大学和高中生暑期实习计划，每年接待一名大学实习生和一名高中实习生。该项目还将继续参与由康奈尔大学植物基因组拓展计划协调的高中教师课程开发研讨会。该项目的当前状态可在http://plbrgen.cals.cornell.edu/programsandprojects/departmental/pawlowski_lab/Wojtek-Projects-Recomb.html上获得

The goal of this project is to examine natural diversity in meiotic recombination in maize. Meiotic recombination is the main source of genetic variation, responsible for creating new gene combinations in the progeny. The role of recombination in evolution of eukaryotes and the mechanisms that regulate recombination frequencies are central questions of modern biology. However, while much is known about the mechanistic aspects of recombination, including a large number of meiotic proteins that have been identified, factors that regulate rates of meiotic recombination remain poorly understood. To understand the quantitative regulation of the meiotic recombination pathway, the extent of variation in recombination rates must first be examined. This study explores the variation in global (across the whole genome) recombination rates using a set of 27 diverse inbred lines that capture over 80% of allelic diversity in maize. The recently developed chromosome painting techniques are used to measure the numbers of crossovers on each of the maize chromosomes. In addition, chromosomal foci of two recombination proteins, RAD51 and MLH1, which mark two main recombination intermediates, are quantified. Natural diversity in key maize recombination genes is also explored. The set of diverse maize inbreds is used to examine variation in DNA sequence of these genes as well as their level of expression. The data generated within the scope of the project will serve as a foundation for future research to identify QTLs affecting meiotic recombination frequencies in maize and to examine associations between the variation of recombination frequencies and variation in candidate recombination genes. Eventually, this research will lead to elucidating mechanisms that regulate meiotic recombination rates in plants.Understanding the mechanisms of recombination is a central issue in plant breeding because recombination generates new genetic variation on which breeders apply selection. Plant breeders could use hyper-recombinogenic lines to reduce linkage drag during introgression of traits, obtain recombinants representing new desirable combinations of genes, use smaller breeding populations, and accelerate the breeding cycle. Outreach and training of undergraduate and high school students are an important part of this project. These activities are integrated into the Plant Genome Outreach Program at Cornell/Boyce Thompson Institute (http://outreach-pgrp.cornell.edu). This program, established in 2003, facilitates a large number of diverse outreach efforts funded by the NSF Plant Genome Research Program. The project will participate in the Summer Internship Program for college and high school students, hosting one college intern and one high school intern each year. The project will also continue to participate in the Curriculum Development Workshop for High School Teachers coordinated by the Plant Genome Outreach Program at Cornell. Current status of the project is available at http://plbrgen.cals.cornell.edu/programsandprojects/departmental/pawlowski_lab/Wojtek-Projects-Recomb.html