We humans are a delicate bunch. We don’t have bark, boney exo-plates, or lush fur to protect us from hostile environments, so we have to steal what other creatures produce just to survive in regions around the only planet that supports us. A few naked days in Earth’s hottest deserts would be more than enough to kill nearly all of us.
If only we had the strength of the Hell-Plant of Death Valley.
Not that scientists at Michigan State University (or actually anyone but me) ever call them that. But as Research Foundation Professor Seung Yon "Sue" Rhee and Research Specialist Karine Prado report in their Current Biology paper “Photosynthetic acclimation is a key contributor to exponential growth of a desert plant in Death Valley summer,” Tidestromia oblongifolia is one hell of a survivor.
Unlike most plants inside or outside California’s hottest desert, where temperatures can blast-furnace up to 49 °C (120 °F), T. oblongifolia actually grows more quickly during Death Valley summers by altering its own photosynthesis to make it more heat-resistant.
While that super-power won’t make T. oblongifolia a tool for terraforming the planet Mercury, the increasing damage of climate chaos demands humanity find any means available to secure its food supply. Unlocking T. oblongifolia’s secrets may provide a blueprint for genetic modification of crops in the world’s hottest (and getting hotter) countries, which did the least to cause climate chaos in the first place.
So, how did Rhee and Prado crack the secrets of T. oblongifolia? Step one was trying to grow the plants from seeds in the laboratory. But according to Prado, success wasn’t that simple. “When we first brought these seeds back to the lab, we were fighting just to get them to grow,” she says.
The problem was that the laboratory conditions were too gentle. So, without referencing Satan in Milton’s Paradise Lost who said, “Better to rule in hell than serve in heaven,” the solution was more hell. “Once we managed to mimic Death Valley conditions in our growth chambers,” says Prado, “they took off."
Using those newly designed growth chambers in Rhee’s laboratory at MSU's Plant Resilience Institute, Prado created hell on earth, or at least the diorama version of Death Valley, complete with punishing light and massive circadian temperature shift. That shift – which flattened the growth of the other heat-tolerant plants in the experiment – took T. oblongifolia from crying to conquering, tripling its biomass in just 10 days.
The secret was T. oblongifolia’s mitochondria (the microscopic power-plants inside cells), which moved closer to the chloroplasts (the organelles responsible for photosynthesis) as those chloroplasts contorted themselves into “cup-like” shapes that scientists had never before recorded in similar plants.
Rhee’s team speculates that such differences may help T. oblongifolia use carbon dioxide more efficiently during photosynthetic production of energy, even under Death Valley’s punishing conditions.
After a single day of extreme heat, thousands of T. oblongifolia’s genes – including those that prevent damage to proteins, membranes, and photosynthetic organelles – alter the processes, while the plant manufactures more of the Rubisco activase enzyme to maintain photosynthesis during high heat.
"This is the most heat-tolerant plant ever documented," says Rhee. T. oblongifolia took only two days to increase its photosynthetic capacity to produce energy and thrive in extreme heat, and by day 14 reached its ideal photosynthetic temperature of 45 °C (113 °F), a global first prize for any known major crop. That championship offers tremendous hope in an increasingly scorching world.
Globally, major crops such as soy, maize, and wheat are already under threat from rising temperatures. By the year 2100 – assuming climate chaos continues accelerating – global temperatures will likely rise by 5 °C (9 °F). Also assuming that humanity still exists, there will be an ever-increasing need not only to grow existing heat-tolerant crops, but to create new ones.
"T. oblongifolia shows us that plants have the capacity to adapt to extreme temperatures," says Rhee. "Desert plants have spent millions of years solving the challenges we're only beginning to face. We finally have the tools, such as genomics, high-resolution live imaging and systems biology, to learn from them. What we need now is broader support to pursue this kind of research."
Source: Michigan State University
