Altered gene helps plants absorb more carbon dioxide, produce more useful compounds

Altered gene helps plants absorb more carbon dioxide, produce more useful compounds
Multiple suppressor of tyra2 (sota) mutations rescued the tyra2 growth inhibition and enhanced tyrosine (Tyr) and phenylalanine (Phe) accumulation. (A) A simplified diagram of the shikimate and AAA biosynthetic pathways. DHS, 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase; E4P, erythrose-4-phosphate; PEP, phosphoenolpyruvate; TyrA, TyrA arogenate dehydrogenase. (B) Plant pictures of 4-week-old Col-0 wild-type (WT), tyra2, and two representative sota mutants of Arabidopsis thaliana. The remaining sota mutant plants are shown in fig. S1. (C) Soluble metabolite profiling and shoot area of the 3-week-old Col-0, tyra2, and sota mutants. Dark and light green bars represent that each sota mutant line showed Col-0–like fully mature green leaves and tyra2-like reticulated leaves, respectively. All the metabolic sota mutants exhibited significantly larger shoot area than tyra2 [one-way analysis of variance (ANOVA) with Dunnett's multiple comparisons test, P < 0.001]. Data are means ± SEM (n = 4 independent plant samples). (D) Relative amounts of Tyr and Phe against Col-0 shown in (C) were plotted for metabolic sota (red circles), response sota (blue triangles), and tyra2 (a black square). (E) Plant pictures of representative complementation lines at T2 generation that were generated by introducing either WT DHS (e.g., DHS1WT) or sota-mutated DHS (e.g., DHS1B4) genes, driven by the respective endogenous promoter, into the Arabidopsis tyra2 background. Scale bars, 1 cm. Credit: Science Advances (2022). DOI: 10.1126/sciadv.abo3416

Every day, plants around the world perform an invisible miracle. They take carbon dioxide from the air and, with the help of sunlight, turn it into countless chemicals essential to both plants and humans.

Some of these chemicals, known as , are the starting material for a wealth of useful medications, such as aspirin and morphine. Yet, many of these chemicals come from because it's hard to get to make enough of them to harvest economically. Others are essential human nutrients and can only be obtained through our food since our bodies are unable to make them.

In new work, scientists at the University of Wisconsin–Madison identified a way to release the brakes on plants' production of aromatic by changing, or mutating, one set of genes. The also caused the plants to absorb 30% more carbon dioxide than normal, without any ill effect on the plants.

If scientists could add a trait like this to crops or drug-producing plants, it could help them produce more chemicals naturally while reducing greenhouse gases in the atmosphere.

"We've long been interested in this aromatic amino acid pathway because it's one of the major plant pathways that transform carbon fixed by photosynthesis into medicines, food, fuels, and materials," says Hiroshi Maeda, a UW–Madison professor of botany who led the new research. "Now for the first time, we've discovered how to regulate the key control knob plants use to turn up production of this pathway."

Maeda and his team, led by postdoctoral researchers Ryo Yokoyama and Marcos Vinicius Viana de Oliveira, published their findings June 8 in Science Advances.

Normally, plants tightly control the production of aromatic amino acids by building in natural brakes to the process. When plants have produced enough amino acids, the whole system grinds to a halt.

The mutated plants Maeda's team discovered using the model plant Arabidopsis have much less sensitive brakes thanks to mutations in a gene called DHS, which starts the production of . The upshot is the plant doesn't know when to stop and keeps churning out these compounds.

The scientists were surprised to discover that the plants put photosynthesis into overdrive, taking in significantly more carbon dioxide into the plant to fuel this new production boom.

"We think that the increased photosynthesis does two things. One is to provide additional energy to operate this energetically expensive pathway. The second is to supply more carbon building blocks to make energetically dense aromatic chemicals," says Maeda.

Some of these energy dense compounds, like lignin, find their way into the , where they make useful biofuel fodder.

Arabidopsis is simply a tiny mustard plant. While a useful model in the lab, it produces nothing of value. Co-author de Oliveira has his sights set on testing similar mutations in crops—which take in huge amounts of carbon dioxide every year—or in plants that produce valuable aromatic chemicals.

"These brakes we identified look very similar among different plants. So, expanding this discovery to crops opens up many possibilities, such as enriching our food with or improving bioenergy production, while capturing more from atmosphere to slow down the global warming," says de Oliveira.

More information: Ryo Yokoyama et al, Point mutations that boost aromatic amino acid production and CO2 assimilation in plants, Science Advances (2022). DOI: 10.1126/sciadv.abo3416

Journal information: Science Advances

Citation: Altered gene helps plants absorb more carbon dioxide, produce more useful compounds (2022, June 8) retrieved 1 March 2024 from
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