By Macie Clugston
Communications Intern
Sugarcane aphid outbreaks in grain sorghum were first reported in 2013. Since then, research has been conducted to learn more about the pests, including a new study by Texas A&M AgriLife Research to evaluate gene expressions in sugarcane aphid-resistant sorghum varieties.
Dr. Ada Szczepaniec, AgriLife Research entomologist, and a team of researchers studied the physiological changes in a commercially available resistant sorghum variety and a susceptible variety. The researchers exposed both varieties to sugarcane aphid infections and studied the effects at two weeks and six weeks post-emergence.
“In prior years, we demonstrated that using sugarcane aphid-resistant sorghum varieties is the most effective way to manage these pests,” Szczepaniec said. “We also documented that when sugarcane aphids colonize flowering sorghum or just prior to bloom, their numbers increase extremely fast. This can pose a challenge to timely insecticide applications.”
Szczepaniec noted results showed the seedling sorghum expressed significantly more genes involved in natural plant resistance to pests than sorghum at the cusp of panicle emergence.
“More importantly, we found a suite of transcriptional changes in the resistant variety that were weak or absent in the susceptible sorghum,” Szcezepaniec said. “Specifically, the aphid-resistant variety exposed to sugarcane aphids bolstered several genes involved in natural plant resistance to pests, and this response was particularly robust in the two-week plants.”
Her new findings strongly support the previous recommendations for managing sugarcane aphids.
“We found specific pathways in the plants that explain how resistant sorghum can mount powerful natural defenses against the aphids and we discovered mechanisms responsible for greater susceptibility of sorghum in reproductive stages,” Szczepaniec said. “These findings further support our recommendations for planting early, using resistant sorghum varieties and intensifying scouting and sampling, particularly when sorghum is flowering.”
The researchers also found gene expression changes in the younger resistant sorghum.
The study discovered how powerful plant hormones entered the younger resistant sorghum, controlling how it reacts to pests. The group also found that genes arranged more effectively to help the sorghum recover from oxidative stress after sugarcane aphid outbreaks.
“The suite of physiological changes we quantified in sorghum was mirrored in the aphid population growth, which was significantly faster in the susceptible and older sorghum than in the resistant and younger plants,” she said.
Research on sugarcane aphids and sorghum’s relationship is relatively new. Before this study, not much information about the molecular mechanisms that result in sugarcane aphid outbreaks had been shared, according to Szczepaniec.
“We believe this knowledge will inform future sorghum breeding programs and contribute to the development of more varieties that can combat sugarcane aphid infestations,” Szczepaniec said.