|Samac, Deborah - Debby|
Submitted to: Plant Reproduction
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2008
Publication Date: 6/1/2008
Citation: Nair, R.M., Peck, D.M., Dundas, I.S., Samac, D.A., Moore, A., Randles, J.W. 2008. Morphological characterization and genetic analysis of a bi-pistil mutant (bip) in Medicago truncatula. Sexual Plant Reproduction. 21:133-141.
Interpretive Summary: Genetic mutations are very useful for identifying genes involved in development of flowers and other plant organs. To date only few floral mutations have been identified in plants in the legume family, which includes pea, bean, and alfalfa. Thus, knowledge of the genes involved in floral development in this group of plants is limited. We identified a mutation in barrel medic plants that had been transformed with DNA to increase resistance to a viral pathogen. These plants develop two separate pistils in contrast to the one pistil found in normal flowers. The pistil receives and transmits the pollen during flower fertilization. The mutation was found to be under the control of a single gene. It is likely that the gene was interrupted by insertion of the foreign DNA during the transformation process. Understanding floral development and the genes underpinning development is important because seed production relies on successful flower development and pollination.
Technical Abstract: A floral organ mutant was observed in transgenic Medicago truncatula Gaertn. plants that had two separate stigmas borne on two separate styles that emerged from a single superior carpel primordium. We propose the name bi-pistil, bip, for the mutation. We believe this is the first report of such a mutation in this species. Genetic and molecular analyses of the mutant were conducted. The mutant plant was crossed to a mtapetala plant with a wild-type pistil. Expression of the mutant trait in the F1 and F2 generations indicates that the bi-pistil trait is under the control of a single recessive gene. Other modifying genes may influence its expression. The mutation was associated with the presence of a T-DNA insert consisting of the alfalfa mosaic virus (AMV) coat protein gene in antisense orientation and the nptII selectable marker gene. It is suggested that the mutation is due to gene disruption because multiple copies of the T-DNA were observed in the mutant. The bi-pistil gene was found to be independent of the male-sterile gene, tap. This novel mutant may assist in understanding pistil development in legumes.