"The wonderful diversity that we see in maize today is the product of many things," Ware explains. "Several million years ago, the genome of the maize effectively doubled in size, to 20 chromosomes, and then, subsequently, returned to its current size of 10 chromosomes. In the detailed sequence that we now have obtained, we can begin to study the impact of that 'doubling event.'"
Ware notes that genome doubling is not uncommon in the plant kingdom, and hypothesizes that "it may be a very successful way for speciation to occur." Once an organism can draw on two full sets of essentially the same genes, it can begin "to de-evolve certain of the genes in one set and adapt them to some other function -- importantly, without compromising the gene's original function," she says. In this way, hypothetically, the plant could become more "capable," in genetic terms, over long periods of time.
The maize reference genome will also provide a basis for close investigation of the impact of human breeding and trait selection, in the much more proximate historical era since the plant's domestication, some 10,000 years ago. Maize is known to have evolved from a common grass found in Mexico and Central America called teosinte. It was human intervention -- breeding -- that led to full domestication and unimagined value and utility. As maize became ever more useful to people -- as food and animal feed -- it was carried beyond the volcanic soils of central Mexican valleys and the indigenous peoples of North and South America to the far reaches of the planet, at first by European mercantile and imperial powers of the sixteenth and seventeenth centuries. It has long been a central cultural element in the region of its initial domestication, but has since worked its way into the sinews of many other cu
|Contact: Peter Tarr|
Cold Spring Harbor Laboratory