#phytochromes

[wayti-blog]

Phytochromes: The 'eyes' that enable microalgae to find their way in aquatic depths

The phytoplankton that populate oceans are known to play a key role in marine ecosystems and climate regulation. Like terrestrial plants, th

"The phytoplankton that populate oceans are known to play a key role in marine ecosystems and climate regulation. Like terrestrial plants, they store atmospheric CO₂, and produce half of our planet's oxygen via photosynthesis. However, the mechanisms that control their distribution remain poorly understood.

By studying the light perception process of diatoms, a group of phytoplankton, scientists from the CNRS and Sorbonne University discovered that these microalgae use light variation sensors which are codified in their genomes: phytochromes.

These photoreceptors enable them to detect changes in the light spectrum in the water column, thereby providing information regarding their vertical position within it. This function is especially important in turbulent aquatic environments subject to substantial water mixing—such as high latitude, temperate, and polar regions—in order to adjust their biological activity, in particular photosynthesis."

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[deepgreenpermaculture]

Why Do Plant Leaves Sometimes Turn Red Under Artificial Grow Lights?

When plants are grown under artificial lighting, such as LED grow lights, the leaves might turn red in colour, due to a phenomenon known as anthocyanin accumulation. Anthocyanins are water-soluble flavonoid plant pigments that produce the major red, blue and purple colours in flowers, fruits and vegetables to attract pollinators and seed dispersers. An interesting fact about anthocyanins is that…

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[cannatuga]

Plants are responsive to temperature, and can distinguish differences of 1°C. In A r a b i d o p s i s , warmer temperature accelerates flowering and increases elongation growth (thermomorphogenesis). The mechanisms of temperature perception are however largely unknown. We describe a major thermosensory role for the phytochromes (red light receptors) during the night. Phytochrome null plants display a constitutive warm temperature response, and consistent with this, we show in this background that the warm temperature transcriptome becomes de-repressed at low temperatures. We have discovered phytochrome B (phyB) directly associates with the promoters of key target genes in a temperature dependent manner. The rate of phyB inactivation is proportional to temperature in the dark, enabling phytochromes to function as thermal timers, integrating temperature information over the course of the night.

Plant development is responsive to temperature, and the phenology and distribution of crops and wild plants have already altered in response to climate change.

[...] We used transcriptome analysis to determine whether disrupted thermomorphogenesis in phyABCDE is specific for temperature signaling or is a consequence of misregulated growth pathways.

[...] Since phytochromes are central regulators of plant responses to the environment, their acquisition of a thermally responsive behavior suggests an evolutionary route to integrate temperature information into development. Single amino acid changes as well as post-translational modifications can alter the dark reversion rate, suggesting sequence diversification among phytochromes affords diversity in thermal responsiveness for different climates. The Pfr dark reversion rate represents a sensitive mechanism to integrate small differences in temperature over the night in order to make developmental decisions.

[currentsinbiology]

 Plant ‘thermometer’ triggers springtime budding by measuring night-time heat

An international team of scientists led by the University of Cambridge has discovered the 'thermometer' molecule that enables plants to develop according to seasonal temperature changes.

Researchers have revealed that molecules called phytochromes -- used by plants to detect light during the day -- actually change their function in darkness to become cellular temperature gauges that measure the heat of the night.

The new findings, published today in the journal Science, show that phytochromes control genetic switches in response to temperature as well as light to dictate plant development.

At night, these molecules change states, and the pace at which they change is "directly proportional to temperature" say scientists, who compare phytochromes to mercury in a thermometer. The warmer it is, the faster the molecular change -- stimulating plant growth.

J.-H. Jung, M. Domijan, C. Klose, S. Biswas, D. Ezer, M. Gao, A. K. Khattak, M. S. Box, V. Charoensawan, S. Cortijo, M. Kumar, A. Grant, J. C. W. Locke, E. Schafer, K. E. Jaeger, P. A. Wigge. Phytochromes function as thermosensors in Arabidopsis. Science, 2016; DOI: 10.1126/science.aaf6005