Source: UNIVERSITY OF GEORGIA submitted to NRP
MOLECULAR CHARACTERIZATION OF REARRANGEMENT AND RECOMBINATION HOTSPOTS IN MAIZE, SORGHUM AND PEARL MILLET
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
NRI COMPETITIVE GRANT
Reporting Frequency
Annual
Accession No.
0203998
Grant No.
2002-35301-15920
Cumulative Award Amt.
(N/A)
Proposal No.
2005-04659
Multistate No.
(N/A)
Project Start Date
Dec 15, 2003
Project End Date
Jun 14, 2006
Grant Year
2005
Program Code
[52.2]- (N/A)
Recipient Organization
UNIVERSITY OF GEORGIA
200 D.W. BROOKS DR
ATHENS,GA 30602-5016
Performing Department
(N/A)
Non Technical Summary
We have very little knowledge regarding the mechanisms or biases associated with recombination or other chromosomal rearrangements in plants. Because we do not know how rearrangement and recombination sites are specified, we are not able to optimize these processes for crop improvement. We will study recombination and rearrangement sities in an unusually unstable region of the maize genome containing the Rp1 disease resistance locus in order to help determine the mechanisms and specificities of these events.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
20115101080100%
Knowledge Area
201 - Plant Genome, Genetics, and Genetic Mechanisms;

Subject Of Investigation
1510 - Corn;

Field Of Science
1080 - Genetics;
Goals / Objectives
This research project is designed to characterize the DNA at sites where recombination and rearrangements events occur in the Rp1 region of maize. Rp1 is a complex disease resistance locus that is found in a particularly unstable region, compared to other regions in maize or to any other known chromosomal segment in any plant species. Hence, recombination and rearrangements occur at frequencies that allow their detection without selection for altered phenotype, which would bias the events that are seen. The insights from these studies will help determine how plant genomes evolve and how recombination can be used to create new genes and new allelic combinations.
Project Methods
We will determine the DNA sequence of several bacterial artificial chromosome (BAC) clones from the B73 rp1 complex, providing more than 480 kb of contiguous sequence. Probes identified in the sequencing process will be used to detect recombined and/or rearranged alleles and to characterize the precise breakpoints of these events. Analysis of these data will indicate the structural genetic determinants, and molecular outcomes, of recombination and rearrangement in this region.

Progress 12/15/03 to 06/14/06

Outputs
OUTPUTS: All of the goals of the project were met, and the final results were the complete sequencing of 876,877 bp of maize DNA including the complete coverage of the complex Rp1 locus. The study of unselected recombination events in this region was also completed, with the discovery of two unequal recombination events, and both were located in the 3' UTRs of rp1 homologues. Regarding results dissemination, these outputs have been presented in several seminars and the DNA sequence information is all available in GenBank for any interested user to peruse and analyze. A publication on the results of the project is now in preparation. PARTICIPANTS: Wusirika Ramakrishna, postdoctoral fellow, conducted most of the sequencing and sequence data analysis. Jesse A. Poland, graduate student, conducted all of the recombinational studies and some DNA sequence analysis. Phillip J. SanMiguel, faculty member, assisted in the DNA sequencing. Scott H. Hulbert, faculty member, assisted in the planning and execution of the project, especially the recombinational component. Jeffrey L. Bennetzen, faculty member, led the planning, execution and completion of the project. Excellent opportunities for training in molecular biology, genetics and genomics were available to postdoctoral fellow Ramakrishna and graduate student Poland. TARGET AUDIENCES: The target audiences for this research are the plant genetics, plant genomics, plant pathology and crop improvement communities. Seminars and publications on this research have and will continue to assist in disseminating the results of this research to this target audience. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The results of this project have dramatically altered our view of the rapid evolution of complex plant disease resistance genes. We already knew that they are rapidly rearranged by unequal homologous recombination, but we now know that these recombination events are not randomly distributed across the disease resistance genes. This may substantially alter our future ability to utilize these genes to create a higher rate of generation of new disease resistance gene specificities.

Publications

  • No publications reported this period