Revealed the secret of light sensitivity of plants


16/12/2010

As you know plants are very sensitive to light, because the light is for them a necessary source of energy, as well as an important condition in which activated special photoreceptors that regulate growth, metabolism, and physiological development. Scientists believe that these light conditions control the growth and development of the plant, resulting in an action or stopping the activity of certain hormones. A new study by biologists at Carnegie specializing in plants has changed the hitherto known theory of how to interact with the light signals and hormones. This new information could be useful in the successful implementation of agricultural crops.

First it is known that the plant hormone called brassinosteroid, necessary for plant response to light signals. This decisive steroidal hormone found throughout the plant kingdom and is responsible for the regulation of many aspects of growth and development. Surprising new study group of researchers led by biologist Zee-Yong Wang (Zhi-Yong Wang) at Carnegie shows that light does not control the level of brassinosteroid found in plants, as expected. Instead brassinosteroid dictates the light sensitivity of the plant. It does this by controlling the production of key protein that reacts to light.

Details of the research group on the interaction with light in brassinosteroid growing seedlings have changed the usual pattern of understanding the relationship between light conditions and hormones in the regulation of photosynthesis and growth. The results were published in the December issue of the publication Developmental Cell.

Although still below the soil surface, in the dark, plant seedlings grow in a special way, which accelerates the process of pushing the stems buds in the air at the same time protecting it from damage. This type of growth is called skotomorfogenez. Once under the rays of light, seedlings switch to a different, more regular, type of growth, called photomorphogenesis, during which the barrel stops growing, and the leaves are broad and green.

Many components are involved in the development process, including brassinosteroid. Previous studies have shown that mutant plants with insufficient brassinosteroid grew as if they were in the world, even when they were in the dark. The study also revealed that many genes responded to stimulation by light and brassinosteroid in the opposite direction. But scientists do not fully understand how this antagonistic process took place, especially after they found that the levels of brassinosteroid in plant cells is not significantly different between plants grown in the dark and the light.

A new study by a team of scientists at Carnegie identifies a protein called GATA2, as a missing connection in the communication system. This protein tells developing seedlings which type of growth to follow.

GATA2 - part of a class of proteins indicator GATA, which are found in plants, fungi and many animals. GATA factors promote the construction of new proteins, the recipes for which are encoded in the DNA. This is done by switching various genes. In Arabidopsis, the pilot plant of the cabbage family, is used in this analysis, there are 29 genes for different members of the family factor GATA. Some of them have shown their influence in the development of the flower, the metabolism of carbon and nitrogen, and the production of the green pigment chlorophyll.

The research team of Wang found that GATA2 comes in a variety of genes whose activity turns on the light, but off BRASSINOSTEROIDS. Then, it became apparent that the protein inhibits the production of brassinosteroid GATA2, light stabilizes and its presence in the plant cell.

Original: Physorg Translation: M. Potter


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