Scientists have identified a mechanism that allows plants to slow growth almost immediately when they face extreme environmental stress. The rapid reaction takes place in a biochemical pathway inside plant cells that produces compounds needed for growth, development and survival. If a key enzyme in this pathway fails, the plant cannot live.
Unlike the common process in many organisms where cells change RNA levels and make new proteins, plants use a faster method. Enzymes already present are modified so their activities change instantly. Reactive oxygen molecules reduce enzyme activity, and some downstream compounds build up and bind to earlier enzymes, blocking them and slowing the whole pathway.
The immediate effect protects leaves by limiting growth-related output. Later, a second phase brings longer-term adjustments that redirect resources away from growth and often result in smaller or slower development. The work, from the Dehesh laboratory, explains why some engineering attempts to boost yields or produce molecules like carotenoids have failed when they ignored this two-stage response.
Difficult words
- mechanism — a process or system that produces an effect
- pathway — a series of chemical steps in cells
- enzyme — a protein that speeds up chemical reactionsenzymes
- compound — a substance made of two or more elementscompounds
- reactive — likely to react chemically with other substances
- downstream — later in a chemical series or process
- redirect — to send or use something in a new direction
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Discussion questions
- How might this two-stage response affect a farmer’s decisions about watering or protecting crops?
- Have you seen plants that grew more slowly after bad weather or lack of water? Describe what happened.
- If you were trying to increase a plant product (for example food or pigment), would you try to change the fast response or the later response? Why?
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