New, low-lignin sorghum germplasm lines developed by Agricultural Research Service (ARS) and collaborating university scientists are now available for bolstering the grain crop's value as both a livestock feed and ethanol resource.

Lignin is a "cellular glue" of sorts that imparts rigidity and strength to plant tissues. It also helps plants fend off attacking insects and pathogens. However, studies by ARS scientists Deanna Funnell, Jeff Pedersen and John Toy in Lincoln, Neb., show that reducing sorghum's lignin content can also be beneficial.

Take, for example, Atlas bmr-12, one of 20 low-lignin lines the ARS team developed and tested in collaboration with University of Nebraska-Lincoln scientists Richard Grant and Amanda Oliver.

In the laboratory, the line scored higher on fiber digestibility than standard sorghum, which should result in higher milk production and higher beef gains when Atlas bmr-12 is fed to cattle. On the fuel front, the line's high fiber digestibility could also mean improved sorghum-to-ethanol conversion at processing plants, notes Funnell. She, Pedersen and Toy are all in the ARS Grain, Forage and Bioenergy Research Unit at Lincoln.

Interestingly, reducing the sorghum line's lignin didn't leave it more vulnerable to fungal attack in laboratory trials. Funnell determined this by inoculating Atlas bmr-12 and another line, bmr-6, with Fusarium moniliforme fungi and examining the length of red-pigmented lesions that formed as the pathogen spread.

Both lines showed greater resistance to the fungus than a control group of standard sorghum that was used. Inside the stems of Atlas bmr-12, for example, fungal lesions were 78 millimeters (mm) long, versus 117 mm in other plants used for comparison in the trials.

Atlas bmr-12 and bmr-6 owe their unique balance of fiber digestibility and disease resistance to two genes for the brown midrib trait, which Pedersen incorporated into the sorghum lines during breeding stages.

Agricultural Research Service