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Associate Professor of Biology
Office: 210 BBIowa City, IA 52242
Office Phone: 319-335-583
Email: email@example.comWeb: More About Dr. Cheng - Related Websites and Resources
BS, Horticulture, National Taiwan UniversityPhD, Plant Physiology, University of Connecticut
Post Doctorate, Plant Molecular Biology, HARVARD UNIVERSITY
Biosciences Graduate ProgramInterdisciplinary Graduate Program in GeneticsInterdisciplinary Graduate Program in Neuroscience
"Molecular and Genetic Analysis of Leaf Greening and Senescence
My laboratory studies the molecular mechanisms by which environmental signals are incorporated into the growth and developmental program of plants. We concentrate on two aspects, greening and senescence of the leaves. Greening occurs at the beginning of leaf development and senescence precedes the death of a leaf. Both greening and senescence are regulated by internal factors, such as hormones and sugar levels, as well as by environmental factors, such as light. We use a combination of classical genetics and molecular cloning technologies to identify genes regulating these developmental processes. The overriding strategy in these studies is to isolate mutants defective in these processes, and use these mutants as inroads to understand the developmental programs leading to greening and senescence. Arabidopsis thaliana is our model organism. Arabidopsis is well suited for genetic analysis. The genetic and physical maps of the Arabidopsis genome are well integrated and its sequence is nearly completed. This facilitates cloning the gene of interest. Once the genes are cloned, we can employ molecular technologies to examine the regulation of the gene’s expression, the biochemical function of the protein it encodes, and the developmental and physiological roles of the protein. The characterization of mutants in greening and senescence is described briefly below.
We have identified mutants defective in greening. One of these, cr88, has been characterized extensively. Genetic, physiological, and ultrastructural studies suggest that CR88 may interact with other components of the photomorphogenesis pathway to play an important role in controlling the greening process, including controlling chloroplast development and the expression of light-regulated genes.
To study the senescence process, we isolated mutants that are delayed in this process. One such mutant, sds1, has been characterized. The sds1 mutant exhibits delays in both natural and artificially induced senescence (see figure). The delays in phenotype correlate with delays in the down-regulation of photosynthetic gene expression and in the up-regulation of senescence marker gene expression. Currently we are characterizing another 20 mutants that exhibit delays in senescence. Because little is known about the regulation of leaf senescence at molecular level, these mutants will be instrumental in understanding how senescence is controlled.
The combination of genetic, molecular biological, and biochemical studies will allow us to understand how the greening process and senescence are controlled during plant development."
Date Last Modified: 06/07/2014 -
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