Researchers Study Genetic Differences Between Domestic, Wild Tomato
April Flowers for redOrbit.com – Your Universe Online
An international team of researchers from the US, Europe and Japan have compiled the first comparison of both the DNA sequences and which genes are active – or being transcribed – between the domestic tomato and wild varieties.
Julin Maloof, professor of plant biology in the College of Biological Sciences at the University of California, Davis, says the findings give insight into the genetic changes involved in the domestication process and may aid in future efforts to breed new traits into tomato or other crops.
Breeding new traits into domesticated tomatoes often involves crossing them with wild relatives. The findings, published in the Proceedings of the National Academy of Sciences (PNAS), reveal that a large block of genes from one particular species of wild tomato is present in domestic tomatoes, and has widespread, unexpected effects across the entire genome.
Maloof’s team examined the domestic tomato, Solanum lycopersicum, and wild relatives S. pennellii, S. habrochaites and S. pimpinellifolium. The effects of evolutionary bottlenecks were revealed when the genomes were compared. Such effects were found at the original domestication in South America, and again later when tomatoes were brought to Europe for cultivation.
The study found, among other things, genes associated with fruit color showed rapid evolution among domesticated, red-fruited tomatoes and green-fruited wild relatives. S. pennellii, a desert tomato variety, was found to have accelerated evolution in genes related to drought tolerance, heat and salinity.
Biologists are being given the unprecedented ability to look at all the genes in an organism by new and emerging technologies. The current study examined not just the plants’ DNA, but also the messenger RNA being transcribed from different genes. It might help to think of the RNA transcripts as the instruction manuals, where the DNA is a list of parts.
Combining an understanding of the plants’ biology with gene-expression profiling allows the researchers to understand how genes interact to create complex phenotypes, according to Neelima Sinha, professor of plant biology at UC Davis.
“Genomics has fast-tracked previous gene-by-gene analyses that took us years to complete,” said Sinha.
“We could not have done a study like this ten years ago — certainly not on any kind of reasonable budget,” Maloof said. “It opens up a lot of new things we can do as plant scientists.”