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Clocks are ticking and climate is changing: Increasing plant productivity in a changing climate

November 16, 2012
Dartmouth College
Scientists are looking to cellular biological clocks as a target for genetic modification for increasing plant productivity.

Dartmouth plant biologist C. Robertson (Rob) McClung is not your typical clock-watcher. His clocks are internal, biological, and operate in circadian rhythms -- cycles based on a 24-hour period. Living organisms depend upon these clocks to keep pace with Earth's daily rotation and the recurring changes it imposes on the environment. These clocks allow the plant or animal to anticipate the changes and adapt to them by modifying its biology, behavior, and biochemistry.


Seeking Knowledge Among the Weeds



Water and the Changing Climate



Water is lost during the gas exchange that takes place in photosynthesis -- carbon dioxide in, oxygen out -- through small pores in the surface of leaves that periodically open and close under the control of a biological clock. Exercising control over this clock could be a means of conserving water. "We know that these little cells on the surface of the leaf are controlled by the clock," says McClung. "It could be that different clocks regulate it slightly differently, and we would like to find the best clock, fine-tune it, and perhaps optimize the ability to get CO2 in without losing water."


New Frontiers



Why and How?


Genetically Modified Organisms (GMOs)

"We will need to genetically modify our plants to control our circadian biological clocks," says Professor Rob McClung. "Every domesticated plant and animal that we have today is already genetically modified. None of them are as they are found in nature. We have manipulated their genes by selective breeding and creating hybrids."

To produce the corn we eat today, prehistoric farmers first had to find some variant that had a desirable trait, keep its seeds and plant them, repeating the process for countless generations to bring out that trait. That is selective breeding and it produced a plant whose genome was modified.

To make a tomato plant resistant to a particular disease or pest, we might find some related pest-resistant species in the wild and cross it with our garden variety tomato to produce a hybrid. Successive crosses would preserve the "tomato-ness" while selectively retaining that little bit from the wild relative that resists tomato-eating bugs.

"Along with introducing the gene or set of genes encoding resistance, we may have also brought in a whole bunch of other ill-defined genes on either side," McClung says. "We don't know the extent of it. We don't know what else is in there. While some regard this as a 'natural' approach, the unknown genetic fellow travelers could be problematic or even dangerous."

For more than 20 years, we have possessed the technology to precisely insert a single gene, making one change and only one change, producing what is known as recombinant DNA. "We are modifying genes in a much more informed way and precise way, targeting specific genes and manipulating those," he says.

"Nevertheless, there is vocal opposition to this practice, in spite of the fact that we have been doing it for decades and there is yet to be a single example of anything bad happening from that," says McClung. "It is a philosophical standpoint based on a lack of understanding. People don't understand the science and they come up with a lot of arguments against it."

The dilemma rests on timing. Conventional breeding, though imprecise and unpredictable, is a workable but lengthy process. Recombinant DNA is fast. In a world beset by overpopulation, famine and global climate change, McClung questions whether we can really afford the time to wait.

Story Source:

The above post is reprinted from materials provided by Dartmouth College. The original item was written by Joseph Blumberg. Note: Materials may be edited for content and length.

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Dartmouth College. "Clocks are ticking and climate is changing: Increasing plant productivity in a changing climate." ScienceDaily. ScienceDaily, 16 November 2012. <>.
Dartmouth College. (2012, November 16). Clocks are ticking and climate is changing: Increasing plant productivity in a changing climate. ScienceDaily. Retrieved February 6, 2016 from
Dartmouth College. "Clocks are ticking and climate is changing: Increasing plant productivity in a changing climate." ScienceDaily. (accessed February 6, 2016).

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