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Race Against Time

by Joan Conrow
Photo courtesy of UC-Davis.

Why are some seemingly dead plants able to return to life — and thrive — as soon as rainfall returns?

That question has intrigued Dr. Jill Farrant since childhood. Now a molecular biologist at the University of Cape Town, South Africa, she's finding clues to breeding drought- and heat-tolerant crops in the genes of plants that appear to "resurrect from the dead."

Farrant has been trying to determine whether the characteristics that enable perennial "resurrection plants" to tolerate drought and extreme temperatures could be bred into annual crops. Her research prompted her to wonder whether these plants are using the same genes that trigger desiccation in seeds — a trait developed some 40-to-60 million years ago.

"Yes, we believe they are," Farrant told those attending the April 18 Plant Breeding Symposium hosted by the University of California-Davis.

That discovery has profound implications for crops like corn, wheat and rice, which account for 95 percent of the cereals cultivated around the world.

"By default, any modern crop has those genes in their roots and leaves because they produce desiccant-tolerant seeds," she said. "They're just turned off."

Resurrection plants are able to switch on these genes whenever drought occurs, not just when they're producing seeds.  One way they protect themselves is by turning their leaves over, which "hides their photosynthesis apparatus from light," she said.

Farrant is using biotechnology and conventional breeding to gain "a comprehensive, fundamental understanding of the mechanism of desiccation" to help her figure out how to activate these desiccant-tolerant traits in food crops, such as tef.

"One or two genes is not going to do it," Farrant said. "We hope to turn on a whole suite of genes that are currently silenced under drought conditions."

Though Farrant has devoted her career to this research, it's taken on added urgency in recent years, as South Africa and other nations on the continent suffer prolonged, severe drought. Significant areas of the globe already have been declared unusable for agriculture due to aridity caused by erratic and declining rainfall, she said. That worrisome trend is expected to increase dramatically by 2050.

"We need drought-tolerant plants," Farrant said. "We're trying to hasten what happens in evolution. We're in a race against time."

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