From online research, the article is;
As days get shorter and colder in the autumn, chlorophyll molecules break down. Leaves quickly lose their green color. Some leaves begin to look yellow or orange because they still contain pigments called carotenoids. One such pigment, carotene, gives carrots their bright-orange color.
But red is special. This brilliant color appears only because the leaves of some plants, including maples, actually produce new pigments, called anthocyanins.
That’s a strange thing for a plant to do without a reason, says Bill Hoch of the University of Wisconsin in Madison. Why? Because it takes a lot of energy to make anthocyanins.
Why red?
To figure out the purpose of the red pigment, Hoch and his coworkers bred mutant plants that can’t make anthocyanins and compared them with plants that do make anthocyanins. They found that plants that can make red pigments continue to absorb nutrients from their leaves long after the mutant plants have stopped.
This study and others suggest that anthocyanins work like a sunscreen. When chlorophyll breaks down, a plant’s leaves become vulnerable to the sun’s harsh rays. By turning red, plants protect themselves from sun damage. They can continue to take nutrients out of their dying leaves. These reserves help the plants stay healthy through the winter.
The more anthocyanins a plant produces, the redder its leaves become. This explains why colors vary from year to year, and even from tree to tree. Stressful conditions, such as drought and disease, often make a season redder.
Now, Hoch is breeding plants for a new set of experiments. He wants to find out whether turning red helps plants survive cold weather.
“There’s a clear correlation between environments that get colder in the fall and the amount of red produced,” he says. “Red maples turn bright red in Wisconsin. In Florida, they don’t turn nearly as bright.”
More protection
Elsewhere, scientists are looking at anthocyanins in other ways. A recent study in Greece, for instance, found that as leaves grow redder, insects eat them less. On the basis of this observation, some scientists argue that red pigments defend a plant against bugs.
Leaves may turn red in the autumn to protect themselves from the sun’s ultraviolet rays.
J. Miller
Hoch rejects that theory, but Lee thinks that it might make sense. He points out that red leaves contain less nitrogen than green ones do. “It may actually be that insects avoid red leaves because they’re less nutritious,” Lee says.
However, “it’s pretty confusing at this point,” Lee admits. “People debate back and forth.”
To settle the debate, scientists will need to look at more species under more conditions, Lee says. So, he’s now researching leafy plants rather than trees. He’s especially interested in tropical plants, whose leaves turn red when they’re young rather than old.
As seen in the Explanation, different people have given reasons why bright red leaves in the fall help protect the trees in the winter. Thus, there is sufficient evidence to conclude that bright red leaves in the fall help protect the trees in the winter.
Step-by-step explanation:
From the article, we can see that Hoch and his coworkers carried out an experiment on mutants and they discovered that plants that can make red pigments tend to continue absorbing nutrients from their leaves a long time after the mutant plants have stopped.
This study and other believe that plants make anthocyanins which acts as a kind of sunscreen to the plants. They also discovered that by the plants turning red, they protect themselves from sun damage
Also, we see that some scientists in Greece found out that as leaves grow redder, insects eat them less and they argued that red pigments defend a plant against bugs and as such Leaves may turn red in the autumn to protect themselves from the sun’s ultraviolet rays.
