Steroids are important hormones in both animals and plants. They bulk up plants just as they do human athletes, but the pathway of molecular signals that tell the genes to boost growth and development is more complex in plant cells than in animal cells. Unlike animals, plants do not have glands to produce and secrete hormones. Rather, each plant cell has the ability to generate hormones. Another difference is that animal cells typically have receptor molecules that respond to select steroids located within a cell's nucleus. In plants, steroid receptors are anchored to the outside surface of a cell’s outer membrane—the membrane that delineates a cell as a single unit.
Zhiyong Wang has spent years homing in on the chemical signaling pathways of one major class of plant hormones called brassinosteroids, making it one of the best-studied aspects of cellular physiology and biochemistry. Brassinosteroids are involved in an incredibly wide array of functions, including response to environmental stresses, cell elongation, and resistance to pathogens. Wang believes brassinosteroids will be a major target for genetically engineering high-yielding crops.
Leaf angle (the orientation of the leaf to the Sun) is critical for optimal energy capture and thus yield; brassinosteroids control this angle. Mutant plants that are deficient in brassinosteroids show defects at many phases of the plant life cycle, including reduced seed germination, irregular growth in the absence of light, dwarfism, and sterility. As such, understanding the brassinosteroid pathway could help researchers improve plant growth and hardiness, which could increase crop yields and help fight world hunger.
The Wang lab has become the leader in uncovering this and other signaling pathways. Recently, Wang and his lab made new breakthroughs in how brassinosteroids are involved in the distribution of a plant’s gas-exchange system, as well as breakthroughs in how a plant responds to changes in light and temperature. Moreover, they discovered a system of “cross-talk,” by which a brassinosteroid interacts with a chemical signaling system controlled by another major class of plant hormones called gibberellins. Together, brassinosteroids and gibberellins form a “command center” controlling plant growth and environmental responses.
Wang received his B.S. in plant physiology from Lanzhou University, China, his M.S. from the Institute of Botany, Chinese Academy of Sciences, and his Ph. D. in molecular, cell and developmental biology at UCLA. For more see http://dpb.carnegiescience.edu/labs/wang-lab