May 9, 2014
LINCOLN, Neb. — Manipulating how plants express their genes holds the promise of higher crop yields and better performance under drought or other environmental stress. University of Nebraska-Lincoln plant scientist Sally Mackenzie is harnessing her breakthrough to improve crops important to developing countries.
Mackenzie discovered that using a transformation technique to turn off a specific gene found in most plants stunts the plant's growth. However, crossing this reprogrammed plant with an unmodified plant produce progeny with greatly enhanced growth, even under stressful conditions.
In a variety of crops these enhancements translate into up to 35 percent higher yields, said Mackenzie, the Ralph and Alice Raikes Chair of Plant Sciences and a member of UNL's Center for Plant Science Innovation.
Importantly, those enhanced characteristics remain stable in subsequent generations without altering their genetic makeup, she said. That's because the process of switching off the gene in the parent or grandparent plant changed how the progenies' own genes are expressed, or their epigenetics. Epigenetics is the study of how genes are expressed through mechanisms other than changing their genetic sequences.
"All crops know this language," Mackenzie said. However this epigenetic technique requires the resources to create an original transgenic plant, resources many countries lack. In addition, some crop plants, such as dry beans, aren't amenable to transgenic transformation.
Now, with support from a nearly $3 million, three-year grant from the Bill & Melinda Gates Foundation, Mackenzie is exploring epigenetics' potential for improving crops for low-resource African farmers.
"With the Gates Foundation grant, we're directing our emphasis more to practical implementation," she said. "So we're also looking at what other technologies we can use to facilitate the transfer of this capability to a less-developed agricultural environment."
In one technique, Mackenzie's team is using a weakened virus to introduce the foreign gene used to switch off the necessary plant gene. If it works, subsequent generations would contain neither the foreign gene nor the virus, but the plant gene would remain off, thus enabling enhanced growth.
In another technique, they're using millet lines epigenetically enhanced in the lab and breeding them to millet grown in Africa to create African varieties with enhanced characteristics.
A third technique uses an epigenetically modified cassava line as a rootstock to graft to an unmodified line. If it works, the enhanced characteristics would be transmitted through the grafted cassavas' seeds.
"What we're doing is really quite novel," Mackenzie said. "And it's in keeping with the spirit of the Gates Foundation: finding simple ways to expedite technology and getting it to developing countries."
Because these epigenetic techniques leave plant genomes unmodified, they eliminate concerns over releasing transgenic plants.
Mackenzie expects that by 2016 they will know if the techniques work. If so, they hope to be able to provide crop material for distribution through collaborating institutions, such as the International Center for Tropical Agriculture.
Mackenzie and her UNL team also are collaborating with researchers at UCLA to study the changes that take place within the genome to cause the enhanced characteristics. Better understanding the underlying biological changes will help researchers improve crop breeding in the future.Sally Mackenzie, Ph.D.
Office of Research and Economic Development
IANR News Service
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