Professor's plant research published in 'Science'

Corrected Tuesday, Sept. 19, 2000 at 8:45 p.m.\nOn the fourth floor of Jordan Hall, professor Carl Bauer and his team of scientists have spent days and nights working on what they consider the most important reaction on Earth. \nThe reaction is photosynthesis and Bauer, post-doctorate fellow Jin Xiong and graduate student William Fischer recently published an article in the Sept. 8 issue of Science explaining the reaction's evolutionary development.\n"The photosynthetic systems that are seen in modern plants originated in bacteria," said Bauer. He referenced research of Distinguished Professor of Biology and Chairman of the Department of Biology Jeffrey Palmer. Palmer's research suggests the modern plant is photosynthetic due to a single event in which a cell draws in a photosynthetic bacterium, which evolved into a chloroplast (the cellular component of plants in which photosynthesis occurs). Thus, by studying the evolutionary mechanism of photosynthesis in bacteria, an understanding of how and in what photosynthesis developed.\nThe finding of Bauer's research was that purple bacteria have the oldest photosynthetic pathway. This contradicts previous theories speculating that green bacteria were the oldest photosynthetic species. It is an important discovery which furthers our knowledge of not only where photosynthesis comes from, but also how it works, Bauer said. \nThe method by which Bauer and his team determined the evolutionary pathway is very similar to the technique used for forensic DNA testing. \n"Evolutionary biology has changed drastically in the last 10 years," Bauer said. "It is no longer sufficient to characterize species by their outside appearance. It is possible to examine the genes that cause those outside appearances. \n"By sequencing the DNA, it is possible to trace the many small evolutionary steps between species and determine the order in which these changes occurred. Modern analytical and computational techniques, some of which were developed here at IU, allow the determination of the DNA sequence within the bacteria, transfer that data to a database, and compare the different species' genetic makeup."\nXiong added, "The evolution of photosynthesis in bacteria is very hard to follow since bacteria traded DNA frequently."\nHe said the family tree of bacteria was more analogous to "spaghetti." It is possible for bacteria to mix DNA with other species of bacteria. This causes the family tree to be very difficult to interpret. With the findings recently reported to Science, we now know one "noodle" of the evolutionary pathway of bacteria, he said. \nDavid J. Des Marais, an editor of Science, recently commended the new approach Bauer is taking in researching photosynthesis. Since life began on Earth 3.8 billion years ago, it is very difficult to understand what early life forms were like, he said. Microfossils from the earliest sedimentary rocks have typically undergone extensive alteration due to their age. However, the genetic makeups of those early organisms are still preserved in the large biological molecules (DNA) and pathways (photosynthesis) of modern species, he said.