In the late 19th century Gregor Mendel used peas to show that one copy of a gene (allele) is inherited from the mother and one from the father. In the progeny, the inherited genes are expressed at the right time and in the right place, but until recently, it was thought that although gene products could be modified during the life of the organism, the genes themselves were unchanged, except for random mutation. Now it appears that one copy of some genes can alter the expression of the other copy, and those changes are passed down to the next generation. These epigenetic alterations, called paramutations may be important in introducing changes when plants and other organisms are environmentally stressed. The exact mechanisms of how genes talk to other genes and change their behavior are being investigated, and recent results suggest that these processes could be important in engineering plants responsive to a variety of environmental conditions.
Dr. Vicki Chandler and her colleagues have studied paramutations in maize and other plants and have identified some of the genes and mechanisms that operate in this epigenetic process. Dr. Chandler, of the Department of Plant Sciences at the University of Arizona, Tucson, will be presenting this work at a symposium on Maize Biology at the annual meeting of the American Society of Plant Biologists in Mrida, Mexico (June 28, 9:10 AM).
The sequencing of genes, proteins, and, ultimately, whole genomes has revealed that genomes are not simply strings of genes, but rather complex, communicating, and interacting regions of information that could be compared to DNA computers controlling growth, development, and metabolism in each organism. The physical architecture of the genome is also highly complex. The nucleus, where the genome resides, is not full of strings of DNA like a pot of spaghetti. Rather, the strands of DNA are wrapped around proteins called histones and the whole is organized into an
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American Society of Plant Biologists