chlorophyll

Growing safer potatoes

January 15, 2025 By EarthWise Leave a Comment

We are often advised to avoid eating green areas on potatoes. The green comes from chlorophyll that occurs naturally when potatoes are exposed to light. It is harmless but when it is there, it can be accompanied by a natural toxin – a substance called solanine, which is a steroidal glycoalkaloid or SGA. Sunlight can produce solanine as well as chlorophyll. Solanine is produced by plants to protect them from insects.

Solanine is bitter tasting so one is unlikely to consume much of it. But consuming enough of it can lead to gastrointestinal complications like diarrhea, abdominal pain, vomiting, and sweating.

Researchers at the University of California Riverside have discovered a way to eliminate toxic compounds from potatoes, making them safer to eat and easier to store. They have identified a key genetic mechanism in the production of SGAs. They found a specific protein that controls the production and believe it will be possible to control where and when SGAs are produced. Thus, it may be possible to have SGAs present in the leaves of potato plants, thereby protecting them from insects, while having none in the potatoes themselves. By limiting SGAs to non-edible parts of plants, they can be safer and more versatile plants. For example, modified potatoes could be stored in sunny places without worry and would always be safe to eat.

Plants have evolved ingenious ways to balance growth, reproduction, and defense. Our growing understanding of these mechanisms can allow people to redesign crops to meet modern needs, increase food safety, and reduce food waste.

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Growing safer spuds: Removing toxins from potatoes

Photo, posted October 14, 2013, courtesy of Elton Morris via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Why Do Trees Change Color? | Earth Wise

December 24, 2020 By EarthWise Leave a Comment

We had a particularly colorful fall in the Northeast this year. Almost everywhere you looked, there were brilliant displays of yellow, orange, and red. The colors of fall are a result of chemistry and environmental events that may have taken place many months in the past.

The color of leaves comes from 4 pigments whose effects are governed by photosynthesis. The one that is actually used in photosynthesis is chlorophyll and it causes leaves to be green. But when a tree begins to prepare for dormancy, it stops producing chlorophyll, the green pigmentation fades, and the other pigments that were already in the leaves become visible.

There are xanthoplylls, which are the yellow pigments that are seen the most in fall trees. They are the same pigments that color egg yolks and sometimes parts of the human eye. They are only produced by plants and appear in humans and animals only through consumption.

There are carotenes, which are the orange pigments found in fruits and vegetables, such as carrots, oranges, some bell peppers and squashes.

And there is anthocyanin, which is the pigment found in blueberries, blackberries, and red or violet roses. Its color depends on the pH level of the plant; higher pH leads to darker color. This is the pigment seen in red maples, black cherry trees, Shumard oaks, and more. Only 10% of trees in temperate climates produce anthocyanin and its red pigmentation and most of those trees are in New England.

All these pigments serve purposes. They help trees absorb light energy, prevent sun damage, and even regulate how much energy chlorophyll produces.

There are complicated chemical and environmental factors at play in fall foliage but when they come together like they did this year, it’s a magnificent spectacle.

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Why Do Trees Change Color?

Photo, posted October 17, 2020, courtesy of John Brighenti via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Lake George Health Report

December 26, 2019 By EarthWise Leave a Comment

The Offshore Chemistry Program, run by the Darrin Fresh Water Institute at RPI, has been monitoring the deep waters of Lake George in New York for 40 years. Lake George, nicknamed the Queen of American Lakes, is famed for the transparency of its water and a new report on the health of the lake reveals that it is doing rather well.

According to the report, although concentrations of chemicals and pollutants like salt and nutrients have increased in the deep waters of Lake George, they are still too low to harm the ecosystem at those depths.

The Offshore Chemistry Program studies the lake as part of a collaboration between RPI, IBM Research, and the FUND for Lake George that is called the Jefferson Project. This long-term commitment provides a wealth of information over time matched by few lake studies in the world.

The recent results show that levels of salt, the nutrient orthophosphate, and chlorophyll have increased substantially over time, but none are yet at a level that will cause harm.

Orthophosphate occurs naturally, but most likely the higher levels are due to improperly functioning septic systems, failing wastewater treatment systems, and stormwater runoff. The orthophosphate most likely triggered the increase in chlorophyll, which probably is associated with increased density of chlorophyll in individual algal cells, rather than an increase in total algal mass in the lake.

Overall, the results demonstrate the continuing resilience of Lake George to a growing array of stressors. In nearly 40 years of human activities, the lake has changed in a number of ways, but the changes have so far been relatively small. With such careful monitoring, we can hope to keep them that way.

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Four Decades of Data Sounds Early Warning on Lake George

Photo, posted September 24, 2009, courtesy of GPA Photo Archive via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.