Scientists from the Agricultural Research Service (ARS) of the United States Department of Agriculture (USDA) recently published a study describing the construction of "linkage maps" for the genome of a biofuel "grass" feedstock. Switchgrass (Panicum virgatum) is a perennial grass, native to North America, and has recently received attention as a promising second-generation biofuel (bioethanol) feedstock. The genetic map was constructed by crossing a commercial variety of switchgrass ("Kanlow") with an ARS-developed variety ("Alamo"), to produce 238 plants. The DNA was extracted from the plants, and the map was assembled, "based on more than 1,000 genetic markers that could each be attributed to one parent or the other". The study, according to the ARS website, "was able to clearly distinguish the two subgenomes resulting from whole genome duplication that resulted in the current tetraploid status of the mapping parents". The study also showed that (1) two genomes do not readily exchange genetic information, and (2) genomes of switch grass and other grasses are "highly collinear". These findings may be able to help researchers identify gene sequences controlling crop yields and plant cell walls, with the objective of eventually developing better "biofuel-grade" varieties for improved bioethanol production. The study is published in the journal, Genetics (URL above).