Sequencing of resurrection grass brings stronger drought-tolerance
A Lazarus heart beats inside an obscure grass. Rip it from the soil, throw it on the counter, walk away and let it dry out and turn brittle. It looks dead and should be dead. But splash on a bit of water and life comes forth.
Recent genome sequencing of Oropetium grass has given researchers a blueprint to distinguish genes related to phenomenal plant resilience. The bizarre self-preservation abilities of resurrection plants such as Oropetium hold tremendous promise for engineering stronger drought tolerance in crops, and the effects could reach soon farmers.
Scientists at the Donald Danforth Plant Science Center submitted an Oropetium sequencing proposal to Pacific Biosciences’ “Most Interesting Genome in the World” grant program. The results will be the first steps to mapping the resurrection trait.
“This discovery is related to all crops in agriculture,” says Robert VanBuren, National Science Foundation postdoctoral scientist, Danforth Center. “Plants use similar pathways during seed drying. The capacity to perform resurrection might be a matter of changing around how the genes are regulated.”
Oropetium endures harsh, rocky terrain in Africa and India. When lacking water, it shows extreme tolerance similar to dessication, when seeds dry out and remain dormant—but viable—for years. The embryo stays alive and can germinate. Essentially, add water and the fuse is lit.
It’s a remarkable trait, but an elusive one lacking in crop grasses. During dry periods, Oropetium locks up and protects its DNA and RNA. “It’s sort of like putting antifreeze in your vehicle to protect it from extremes,” VanBuren says. “This is an understudied phenomena as a seriously promising path for crop improvement.”
VanBuren isn’t seeking extreme dormancy in crops, but better endurance under stress. “We want to boost crops in periods when they would normally lose production,” he says. “Essentially, we’re looking for better performance in crops, not resurrection.”
The genome-sequencing effort was performed with PacBio’s SMRT (Single Molecule, Real-Time) technology. With SMRT Sequencing, genome sizes such as Oropetium can be sequenced in two days—and only a matter of weeks for larger plant genomes such as corn. With these falling costs and technological leaps, breeding programs have unprecedented access to genome sequencing. Ag companies recognize the need to overcome genetic bottlenecks in major crops. Narrow gene pools leave crops highly exposed to pest pressure, disease and weather extremes, according to Jonas Korlach, chief scientific officer, PacBio.
“After centuries of breeding, genetic diversity has decreased, partly through the pursuit of yield. With this technology, we can think about sequencing multiple strains of a particular crop and wild varieties,” Korlach says.
Every genome tells a story. The genes within explain the adaptation of an organism—the nuts and bolts of survival and prosperity. Oropetium has amazing drought tolerance, and the genetic reason for its stamina is hiding inside the genome.
“We will identify Oropetium genes that confer the ability to withstand drought,” says Todd Mockler, associate member, Danforth Center. “We’ll do it in a research context, but an ag biotech or seed company will deploy it in a commercial context.”
Whether through GMO technology, computational breeding, advanced genome editing, RNAi or another technology, the door to transfer resurrection genes into plant crops is opening. Mockler’s goal is to make heartier crops that stand tough against drought, as well as provide benefits during standard weather years.
Oropetium’s Lazarus heart is enabling a marriage of resurrection plants and field crops. VanBuren and Mockler will next test genes related to resurrection properties by placing them in model plants. “When we see boosted drought-tolerance, we’ll be ready to insert the genes into crops,” VanBuren says.