University Park, Pennsylvania, USA
July 13, 2011
The molecular mechanisms that control genetic modifications in specific tissues during plant development are the focus of a National Science Foundation grant for $1.2 million to Surinder Chopra, associate professor of maize genetics in Penn State's College of Agricultural Sciences.
The three-year project is a collaborative effort with the University of Delaware, which will provide training opportunities in plant epigenetics and the study of variation of plant genes. Epigenetics studies the situation when genes' functions are modified without any change in their DNA sequences, sometimes creating silent genes whose characteristics are not expressed in the organism.
The research aims to produce the means for scientists to make precise genetic modifications in plants, Chopra explained. "Crop improvement is brought about by the use of genetic and breeding strategies that allow combination of genes from different parental lines into new germplasm --inbred lines and then hybrids," he said. "The key to the success of a new hybrid is the stable inheritance of its traits -- or genes. However, genes that eventually become silent because of unknown epigenetic modifications lead to a breakdown of the cultivar. This research will allow us to identify genes in the maize plant that are candidates for epigenetic gene silencing."
After researchers learn about these genes and their regulation, Chopra noted, the process of genetic modification by plant breeding will become more effective and efficient because scientists can select required alleles of genes that can be stably inherited over generations.
Genes "express" in different parts of the plant, depending upon the proteins needed in those tissues, Chopra pointed out. Regulation of gene expression in higher living organisms -- including plants -- is controlled by molecular mechanisms, which can restrict the expression to a specific signal, developmental stage, tissue or cell.
"So, when a gene's expression is not needed, the gene can be shut down -- called gene silencing -- by regulatory mechanisms."
The research will build a basic understanding of what causes the instability of genes, Chopra said. "This project is focused on understanding the function of genetic modifiers that regulate gene expression via epigenetic pathways. Such modifiers can then be used in breeding programs for specific agronomic traits."
The project will also undertake a genome-wide search to find all the genes that are epigenetically affected in certain maize lines.
Penn State graduate students PoHao Wang, Kameron Wittmeyer and Nur Suhadha are using genetic and molecular techniques to identify and map epigenetic factors. A number of graduate and undergraduate students and postdoctoral fellows at both institutions will work with faculty. They will be cross-trained in computational biological aspects and epigenetic gene regulation, according to Chopra.
Students will learn classical and cutting-edge plant-biology techniques that are used to understand and dissect the molecular basis of regulation of tissue-specific gene expression.
In addition, as part of the project, high school students and teachers will participate in a summer biotechnology workshop to learn gene-expression techniques in maize.
"The study of gene-expression stability and instability allows us to understand how different plant traits are inherited and how plants cope with different environmental stresses," Chopra said. "After all, environment has a big influence on plant gene-expression modifications, and some of these influences are via epigenetic changes that are transmitted for multiple generations."
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