We are carrying out several basic research activities to support our breeding efforts.
In our effort to develop a functional marker for Ga1-S a key step will be to identify the gene controlling the trait. Toward this end, we propose to reconstitute the pollen-silk interaction in vitro. We will carry out pollen germination studies in the presence of silk extracts from genotypes that are compatible or non-compatible with the pollen being tested. This system will allow us to test products of candidate produced in a heterologous expression system. An alternative approach will be to make antibodies specific to the candidate genes and examine their effect on pollen germination activity in our in vitro system. Finally, we may be able to purify the protein responsible for the activity from silk extracts to confirm which of our candidate genes is responsible. Additional benefits of this system are that it may work for characterization of the Tcb1 and Ga2 loci as well, contributing to development of functional markers for these loci. It may be possible to develop a pollen compatibility assay that can be applied to plants in the field. Pollen could be sampled from different plants and their compatibility with silk extracts can be determined in the lab the same day. Breeders could then select plants to be used in crossing based on the results of this assay. Conventional phenotyping methods require crosses and observation of kernel development on the resulting ears. The results of this test would not be available for weeks, much too late to be helpful in pollination decisions.
Figure: Map of the region around Ga1 showing genes annotated in B73 and sequences from four BACs derived from a Ga1-M line that cover the region.