Feedstock Development projects
Reproductive Barriers in Miscanthus Sinensis and Other Biofuel Plants - Completed
Miscanthus x giganteus is a sterile hybrid between M. sinensis and M. sacchariflorus so they cannot be modified in the usual way by breeders. By understanding and surmounting the reproductive barriers, genetic modification of biofuel crops that are sterile can occur. McCormick studied the genetics of self-incompatibility (SI), which prevents self-pollination. She mapped molecular markers that are linked to self-incompatibility in other grasses.
McCormick’s group performed over 1,200 reciprocal crosses within a population of 160 progeny grown from seed, and deduced self-incompatibility phenotypes; i.e. two plants that shared all alleles at the S and Z loci blocked all the pollen and were incompatible, while plants whose alleles differed had some or all successful pollen and were partially or fully compatible. Her group provided leaf samples from the above phenotyped plants to the University of Illinois for genotyping with molecular markers.
McCormick’s group identified two plants with leaky SI, which show compatible-like pollen tubes after self-pollination. They characterized the SI loci in M. sinensis. The group has identified several SI candidate genes, determined which have the required tissue-specific gene expression patterns, and plan to sequence these genes from multiple individual M. sinensis plants, in order to determine if there is sequence variability for different alleles, as is predicted for genes controlling SI. McCormick’s group also tested several treatments that may potentially overcome SI. The most successful was brief, high-temperature treatments of cultured ovules, which substantially overcame SI (in the in vitro pollination assay) in most plants tested.