Quantifying Selfing and Outcrossing Fertility in Lowland Swtichgrass Populations Using Ssr Markers

Abstract

Switchgrass (Panicum virgatum L.), a native C4 perennial species, is being developed as a major cellulosic crop for biofuel feedstock production in the U.S. However, no information is available on mating behavior of plants under open pollinating conditions in the field. Accordingly, the objective of this study was to quantify selfing and outcrossing rates of switchgrass plants grown in the field. Two small (NL94 C2-3 and SL93 C2-3), each having five parents, and two large (NL94 C3 and SL93 C3), each having 26 parents, lowland switchgrass breeding populations field established with three replications were used in the experiment. Ten seedlings from open-pollinated seeds of each parent in each replication per year were planned to grow in a greenhouse at the Agronomy Research Station, Oklahoma State University. In 2010, DNA samples were isolated from 1700 progeny of 62 seed parents while DNA samples were extracted from 773 progeny of 42 parents in 2011. Sixteen Simple Sequence Repeat (SSR) markers were used to identify breeding origins of the progeny plants as compared with respective seed parents. Among 2473 progeny examined over two years, only one plant of SL 44 was identified to be selfed, indicating an extremely high outcrossing rate of 99.96%. The findings should help to better understand the sexual reproduction characteristics of lowland switchgrass and the identified selfed progeny could be useful in inbred line development.