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
