Humans are dependent on plants as critical sources of food, fuel, and fiber. Understanding the biological principles that govern the growth and development of plants therefore has great practical value. The science of plant genetics provides one of the most productive approaches to understanding plant biology. Recent advances in genome science have provided a rich suite of tools and resources that have greatly accelerated the pace of plant genetics research. Missing from the plant scientist's toolbox, however, is a practical strategy for engineering precise deletions of genes at chosen positions in the DNA on a chromosome. This Early-concept grant for Exploratory Research (EAGER) project will address this deficiency by testing a promising new strategy for producing targeted genome deletions in plants. The resulting technology has the potential to be widely adopted as a standard tool for exploring gene function in plants. In addition, the project will provide training opportunities for students at the graduate and undergraduate levels.
The research team recently described the isolation of a unique Arabidopsis thaliana mutant carrying the precise deletion of three tandemly-duplicated genes on chromosome IV. This deletion appears to have been caused by an unequal meiotic crossover directed by T-DNA insertions located 25 kilobases apart in the genome. This deletion was found by screening 2,000 F2 plants by PCR to search for recombinants. Because only one instance of this deletion was observed in the previously published work, it is impossible to accurately estimate the rate with which these deletions occur. In order to determine the potential value of this system for performing genome engineering the following studies will be performed: 1. Measure the rate with which T-DNA directed deletion occurs at several loci throughout the genome. 2. Determine the effect that T-DNA structure has on deletion frequency. The T-DNA insertions that produced the previously characterized deletion had an inverted-repeat structure. The correlation between hairpin-forming ability and deletion rate will be explored. If successful, this research could ultimately lead to the development of genome engineering methods that could be applied to a wide range of plants species, including crop plants.
