Genetic Analysis of Rust Resistance Gene(s) in Switchgrass Cultivar ‘Alamo'.

Switchgrass (Panicum virgatum L.) is a perennial C4 grass that is considered a prime candidate for large-scale biomass production for lignocellulose-derived bioenergy. Breeding efforts targeting the improvement of switchgrass biomass in the U.S. are very recent. To achieve large-scale, sustainable and economical biofuel production in the near future, potential disease problems of switchgrass must be mitigated, through both basic and applied research. We recently surveyed 168 switchgrass lines with switchgrass rust pathogen (Puccinia emaculata), and showed that more than 90% switchgrass lines deposited in the USDA germplasm bank are highly susceptible to switchgrass rust. Lowland cultivars ‘Alamo’ is highly resistant to the rust populations collected from the Agricultural Station of Virginia Tech. The rust resistance genes in switchgrass cultivar ‘Alamo’ were characterized in a new F1 mapping population derived from a cross between ‘Alamo’ and an upland cultivar ‘Dakota’ that is high susceptible to the rust disease. A total of 147 F1 individuals were used for mapping the rust resistance genes with microsatellite (SSR), sequence-related amplified polymorphism (SRAP) markers, and the NB-LRR gene profiling strategy. The molecular markers linked to the rust resistance genes will be valuable tools for marker-aided selection in switchgrass breeding programs.