Too much exposure to far-red light was harmful to plants, according to the study
Light wavelengths can impact how plants develop their chloroplasts — which determine how green the plant is — according to a new study published in American Journal of Botany.
Chloroplasts are organelles that conduct photosynthesis using sunlight and carbon dioxide. They contain pigment chlorophyll, which captures the energy from sunlight, converts it, and stores it in the energy-storage molecules. Chlorophyll is what gives plants their green colour.
According to scientists, the strength of light emission or its wavelength can determine the greenness of a plant.
Scientists from Michigan State University’s MSU-DOE Plant Research Laboratory examined how far-red light — at the extreme end of the visible light spectrum — impacts chloroplast development in seedlings.
Far-red comes before infra-red, in the visible light spectrum. Plants detect the wavelength through light-absorbing signalling proteins called phytochromes.
According to researchers, protein Sigma factor 6 (SIG6), also known to contribute to chloroplast development, plays a crucial role in early stages of a plant’s life.
“If we expose wild plants to excessive amounts of far-red at an early stage and then transfer them to normal white light, they do not ‘green’, said Hussien Alameldin, a researcher at the University’s Montgomery lab.
“In other words, the chloroplasts don’t accumulate enough chlorophyll pigments and are thus less healthy and productive,” he added.
This meant that too much exposure to far-red was harmful to plants.
To understand why, researchers tested lab plants under extreme far-red exposure.
They grew mutant plants — each missing a gene related to chloroplast development. After exposing the plants to far-red light over the first five days of growth, they transferred them back to normal white light to examine how each mutant fared.
Researchers noted that plants without SIG6 protein — which plays a crucial role in early stages of a plant’s life — stood out. They developed green leaves even under extreme conditions.
“This indicated that SIG6 played a role in regulating of greening mechanism,” said Alameldin.
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