Gametophyte project

NSFlogo NSF-Plant Genome Research Program Award #0701731

Functional Genomics of
Maize Gametophytes

Mutation analysis continues to be a powerful tool to investigate the function of genes. In plants, there is a whole class of genes that are difficult to analyze in this fashion, because they cannot be transmitted through the gametophyte generation. I am part of a group that is generating and propagating a collection of just such mutants, specifically those that affect the female gametophyte. We are using the Activator transposable element system to generate the mutations in plants that are trisomic for selected chromosomal regions.

Standing left to right: Erica Unger-Wallace, Allison Phillips, Matt Evans (PI), John Fowler, Scott Givan.
Kneeling: Erik Vollbrecht, Don Auger

The cartoon below portrays three chromosomes in the nucleus of a cell. The B-A chromosome is a translocation involving a supernumerary B chromosome with an essential A chromosome. Below it are two A chromosomes; one carries the Activator (Ac) transposable element. If the Ac transposes into a gene that essential to the gametophyte (G), it will result in a situation where this chromosome would normally be lost soon after meiosis due to abortion of the gametophyte. This is because the two A chromosomes separate at meiosis-I and the newly mutated gene (g) is no longer complemented by a functional allele (G). The B-A chromosome creates a segmental trisomy for the region that includes the mutation. Because it segregates independently of the two A chromosomes, it will co-segregate with the mutation half of the time. This will allow for complementation of the mutation and its survival to the next generation. The presence of the B-A can be detected phenotypically by a reporter gene (R1), which causes mature kernels to develop color. The reporter gene also is key to detecting gametophyte mutations due to altered segregation ratios.

09/09/09