Stanford, CA Plants are very sensitive to light conditions because light is their source of energy and also a signal that activates the special photoreceptors that regulate growth, metabolism, and physiological development. Scientists believe that these light signals control plant growth and development by activating or inhibiting plant hormones. New research from Carnegie plant biologists has altered the prevailing theory on how light signals and hormones interact. Their findings could have implications for food crop production.
It was previously known that a plant hormone called brassinosteroid is essential for plant's responses to light signals. This crucial steroid-type hormone is found throughout the plant kingdom and regulates many aspects of growth and development. Surprising new research from a team led by Carnegie plant biologist Zhi-Yong Wang shows that light does not control the level of brassinosteroid found in plants as was expected. Instead brassinosteroid dictates the light-sensitivity of the plant. It does this by controlling the production of a key light-responsive protein.
The team's findings on interactions between brassinosteroid and light in sprouting seedlings have changed the prevailing model for understanding the relationship between light conditions and hormone signals in regulating photosynthesis and growth. Their results are published in Developmental Cell on December 14.
While under the soil's surface, in the dark, plant seedlings grow in a special way that speeds the process of pushing the budding stem out into the air, while simultaneously protecting it from damage. This type of growth is called skotomorphogenesis. Once exposed to light, seedlings switch to a different, more regular, type of growth, called photomorphogenesis, during which the lengthening of the stem is inhibited and the leaves expand and turn green.
Many components are involved in this developmental switch, including brass
|Contact: Zhi-Yong Wang|