HESS CENTER FOR PLANT SCIENCE

Global climate change is here. Each day, new headlines describe record-high temperatures, melting ice caps, coastal flooding, brush fires and persistent droughts. And as temperatures rise, crops fail and malaria, dengue fever and other diseases spread to new locations. Climate change is a dozen different crises all rolled into one.

Approximately two-thirds of the total energy imbalance that is causing Earth’s temperature to rise is due to increases in carbon dioxide in our atmosphere, says the US National Oceanic and Atmospheric Administration.

The planet absorbs around 746 gigatons of carbon dioxide each year through photosynthesis and other mechanisms (one gigaton is 2 trillion pounds). Much of that carbon is pushed back into the atmosphere when plants die or shed their leaves each fall. This natural cycle has been thrown out of balance by human activity that currently releases 18 gigatons more carbon than the planet can absorb.

We must find ways to adapt to a warming planet. At the same time, we must take steps to reduce the amount of carbon in our atmosphere and mitigate the effects of climate change.

Salk scientists have never been content to simply keep doing things the way they’ve always been done. While some researchers are focused on preserving habitats, plants and animals as they exist today—a noble cause, to be sure—we believe that won’t be enough to ensure survival in this century and beyond. That’s why scientists in our Harnessing Plants Initiative are developing Salk Ideal Plants®, a new generation of food crops that are better equipped to survive—and even thrive—in hotter, drier, less-than-hospitable environments.

Salk Ideal Plants are also being engineered to sequester excess carbon from the atmosphere. The key is longer, deeper roots and molecules such as suberin, a carbon-rich polymer found in cork, avocado skins and plant roots. Because suberin is mostly carbon and is more resistant to decomposition than most plant material, it is very good at capturing and storing carbon from the atmosphere—and thus has great potential to help stabilize our climate.

Investigating how plants grow and thrive is a lot like studying neurology, metabolism, immunity or any other networked system: many components contribute to the system’s ultimate function.

This gives Salk a tremendous advantage.

In our Harnessing Plants Initiative, experts bring deep knowledge in genetics, genomics, epigenomics, plant biology, computational biology and many other disciplines. They leverage Salk’s greenhouse facilities to interrogate specific plant genes and study the traits they produce. They can reproduce the climate of almost any location on Earth in climate-simulation chambers. They use X-rays, machine learning and other tools to measure root growth and suberin content.

Together, this team provides an interdisciplinary framework to assess how plants operate and to reprogram them with two goals: to withstand and restore Earth’s climate.

For more than 30 years, Professor Joanne Chory, founding director of the Harnessing Plant Initiative, has studied Arabidopsis thaliana, a small flowering mustard plant, to understand plant growth and adaptation. She pioneered the use of genetics to study how plants alter their sizes, shapes and forms to optimize growth and maximize photosynthesis. Her work has illuminated the complex signaling networks that control plant growth and development.

Chory, Professor Joseph Ecker and team recently showed that shade from close-growing neighbors causes plants to grow taller. The study looked at the role of proteins called transcription factors in activating this growth response. Transcription factors are proteins that turn genes on or off by binding to DNA.

The team worked with mutant Arabidopsis seedlings that lacked transcription factors called PIFs. When the team grew these plants in simulated shade, the plants without certain PIFs did not elongate or speed up their growth, suggesting that those PIFs are necessary for rapid growth. Further experiments showed that within five minutes of shade onset, one particular PIF gets activated and removes a molecular brake sitting on growth genes. With the brake lifted, shaded plants are free to shoot up. Chory and Professor Wolfgang Busch also identified PIFs that help regulate root growth in response to temperatures.

In addition, Associate Professor Julie Law recently discovered the genes that are turned on or off, and in which order, to orchestrate the cellular processes required to protect and repair plant genomes in response to DNA damage—something that happens more frequently in stressful environments.

These findings provide examples of how plants respond to subtle environmental changes on a molecular level, as will increasingly occur as plants adapt to global climate changes. Studies such as these also open new avenues for scientists to optimize plants to grow in less-than-ideal lands (including shady areas) and withstand heat waves, droughts, floods and pests.