Long before plants and animals inhabited the earth, when life consisted of single-celled organisms afloat in a planet-wide sea, bacteria invaded these organisms and took up permanent residence. One bacterium eventually became the mitochondria that today power all plant and animal cells; another became the chloroplast that turns sunlight into energy in green plants.
A new analysis by two University of California, Berkeley, graduate students more precisely pinpoints when these life-changing invasions occurred, placing the origin of photosynthesis in plants hundreds of millions of years earlier than once thought.
“When you are talking about these really ancient events, scientists have estimated numbers that are all over the board,” said coauthor Patrick Shih. Estimates of the age of eukaryotes – cells with a nucleus that evolved into all of today’s plants and animals– range from 800 million years ago to 3 billion years ago.
“We came up with a novel way of decreasing the uncertainty and increasing our confidence in dating these events,” he said. The two researchers believe that their approach can help answer similar questions about the origins of ancient microscopic fossils.
Shih and colleague Nicholas Matzke, who will earn their Ph.D.s this summer in plant and microbial biology and integrative biology, respectively, employed fossil and genetic evidence to estimate the dates when bacteria set up shop as symbiotic organisms in the earliest one-celled eukaryotes. They concluded that a proteobacterium invaded eurkaryotes about 1.2 billion years ago, in line with earlier estimates.
Read more at: Phys.org