Genetic Map-Based Analysis of Paleopolploidy in Homosporous Ferns

Indiana University, Bloomington IN

Investigators

Abstract

The world's plants consist of homosporous plants, best represented by ferns, and heterosporous plants, best represented by seed plants. Homosporous species have high chromosome numbers, suggesting that they are products of repeated cycles of doubling of chromosome numbers (polyploidy) followed by gene/genome silencing. This project will address the question of ancient polyploidy by generating high resolution genetic maps of the 39 chromosomes of Ceratopteris richardii, the fern species used as a model organism for studies of homosporous plants. DNAs from 500 completely inbred hybrid plants (DHLs) will be analyzed with approximately 1000 molecular markers. Analyses of the chromosomal locations of duplicate markers will make it possible to determine whether the Ceratopteris species is an ancient polyploid. Homosporous plants are now known to share an immediate common ancestor with seed plants, a group that includes all agricultural food plants. This project's genetic maps will provide fundamental information about genomic structure of homosporous plants, which in turn will provide basic comparative data bearing on evolutionary processes that produced the genomic organization of all of today's plants. In addition to the genetic maps, the 500 fully genotyped DHL plants will be cloned and made freely available to biologists for future genetic studies.