By Avigayil Kadesh
A serendipitous discovery in an Israeli laboratory has led to a revolutionary advance in growing food crops with higher yields and resistance to drought and other stresses.
Drought resistance is a kind of Holy Grail in the plant sciences world, especially as the planet’s population grows amid a crisis in water, food and energy availability. Israel’s scientists have done some significant work in this field.
But until Technion Prof. Emeritus Shimon Gepstein happened on his discovery, nobody knew cytokinin -- a known “juvenile” hormone in plants -- had any bearing on drought resistance.
“This was the first report of a new mechanism,” he says. “I found it by accident, while I was working on a completely different mechanism having to do with plant aging.”
When plants yellow and droop at the end of the season, that is because their level of cytokinin has fallen. Gepstein studied the genetics of plant aging using tobacco, and saw that photosynthesis in the leaves could continue if the cytokinin gene were engineered to extend its activity.
“We succeeded in extending the lifespan of tobacco plants from four months to seven months, and the yield was therefore much higher,” he reports. Not only that, but shelf life also was extended.
These findings alone were significant. Then, Gepstein’s lab team neglected to water the engineered tobacco plants for a few weeks. To the scientists’ surprise, the thirsty plants bounced right back after getting re-watered, and only needed half the usual amount to flourish.
“So we started with delaying aging and ended up with a completely different story that is not less important and maybe more important,” says Gepstein, who has advanced degrees in plant physiology from Tel Aviv University and did his postdoctoral work at the University of California, Santa Cruz, on plant hormones.
The ability to survive after three weeks of drought has great implications in Israeli agriculture. “In Israeli winter, after the first rain the wheat seedlings germinate and then if no more rain falls for a few weeks, they die. If modified plants can withstand this dry period until the second rains come weeks later, we can save the whole field,” he says.
And because they require much less water, these food crops could be grown in more arid zones.
“This linkage between delay of aging and stress tolerance is new,” Gepstein emphasizes, “as well as the discovery that cytokinins have a major role in drought tolerance.”
The technology was later patented and licensed by the universities to a California agro-tech company, which sublicensed it to several seed companies. A Chinese patent was approved in July 2013, heralding a huge new market for this advance.
“This technology has been introduced in several major crops in the world -- rice, wheat, sugar beets, cotton, millet and others – and has been the subject of papers by other labs using our technology, because it’s being recognized in the world,” says Gepstein, former president of the Israeli Association of Plant Sciences and current president of Kinneret College on the Sea of Galilee.
Normally, says Gepstein, it takes about a decade for a technology of such import to make it from lab to field, if indeed it ever gets commercialized.
This extraordinary discovery – that a single modified plant hormone can increase shelf life, yield and ability to withstand drought -- was fast-tracked even as additional research continued in his lab at the Technion in Haifa.
A forthcoming scientific article based on that research will show the additional modification also protects crops against stresses such as cold, heat, salinity, insects and parasites.
Though many consumers are wary of genetically modified produce, Gepstein explains that his lab’s approach avoids the unknown risks involved in crossing all the genes of two plants or adding genes of a different species.
“We did not introduce any foreign genes; we just extended the activity of the natural gene of one hormone that is already in the plant. It’s completely native,” he says. “It’s more accurate and healthier because you know exactly what you are doing.”
A California-based company is marketing the engineered seeds to growers worldwide.