Medicago sativa (alfalfa) is the fourth largest U.S. crop by land area, with a history of gene-flow problems. Plastid localization is an effective tool for transgene containment in crops with strict maternal plastid inheritance, but its use depends on the availability of tools for plastid transformation. M. sativa transmits plastids maternally, paternally or biparentally. Currently no information exists detailing the genes responsible for plastid inheritance nor has plastid transformation been reported in alfalfa. As the first step towards engineering plastid inheritance in alfalfa, we propose a survey of natural variability of plastid inheritance in Medicago truncatula, a related diploid model species, since the tetraploid M. sativa is not suitable for genetic analyses. We have already demonstrated maternal and biparental plastid inheritance in a small subset of M. truncatula accessions. We now propose to extend the screen to 30 lines to encompass a broader spectrum of inheritance modes. In addition, we shall determine the dominant-recessive relationships between the maternal and biparental modes of inheritance as well as the number of genes in a segregating population. Scoring of plastid types in the progeny will be based on polymorphic DNA markers and on visual markers introduced by plastid transformation. Information on plastid inheritance phenotypes will be useful for association mapping of the relevant genes and for selecting or engineering alfalfa for strict maternal plastid inheritance. Plastid transformation in alfalfa developed through this project will enable better containment through plastid localization of transgenes, therefore meeting the objectives of the BRAG risk management research.
|Effective start/end date||9/1/09 → 8/31/10|
- National Institute of Food and Agriculture (National Institute of Food and Agriculture (NIFA))