Picking strawberries

Picking strawberries

Photo Credits: COURTESY

Sequenced strawberry genome may pave way for the breeding of higher quality strawberries

As a result of the collaboration between scientists at UC Davis and Michigan State University, strawberry cultivators may be able to use its DNA as a guide to breed strawberries with certain qualities pertaining to color, taste, shape and aroma.

In a recent article titled “Origin and evolution of the octoploid strawberry genome,” a team of researchers including Steve Knapp, a professor in the Department of Plant Sciences and director of the Strawberry Breeding Program, and Patrick Edger, an assistant professor in the Department of Horticulture at Michigan State University, revealed their sequencing of the genome for the cultivated strawberry, after having analyzed its origins and evolutionary process.

“I think one of the primary drivers [for our research] is that [the] strawberry is an octoploid, which means that it has eight sets of chromosomes which makes it really unique compared to humans because humans, we have one set of chromosomes from each one of our parents,” Edger said.

The researchers looked into how the strawberry attained eight sets of chromosomes and if there were any genetic variations resulting from this difference compared to diploids. Edger explained that once they had sequenced the genome, the scientists identified where each gene was and sequenced the RNA from the genes for every species of strawberry from their global species collection. From there, they conducted a phylogenetic analysis to discover the evolutionary origins of each gene.

“What was very interesting is that as the genome was sequenced, a clear picture emerged of how the ancestral species have gone around the world from East Asia over to Land Bridge to North America, and just how the species formed and how everything evolved was really fascinating,” Knapp said.

The researchers found that the progenitor species were native to Japan, Asia and Eastern Europe and North America. Edger explained that they had predicted potential conflicts in the development of the octoploid due to the progenitor species evolving in different environments, which would likely result in conflicts in the timing of genes being expressed. However, they found that a subgenome, called the woodland strawberry, controls a majority of the traits being expressed by the octoploid.

With this sequenced genome, Edger stated that they can now begin implementing molecular breeding to select for “good genes,” such as those that indicate good fruit quality, which promotes faster breeding. He described this process as a “23andMe for strawberries” where the genetics of each strawberry in a breeding program can be identified. Knapp explained that the use of this information for the agricultural industry was a large reason in conducting this research.

“You’ve got a long string of DNA code and they’re all addresses and without the address I don’t know where to go to find a gene that I need for resistance to a disease or for a fruit quality attribute,” Knapp said. “So the genome is a foundation, it’s a roadmap type foundation to track genes and understand how they make a strawberry a strawberry and how a plant is fighting off pathogens or pests. So the practical implications of it are that we have a tool now to do this kind of genetics research so that we can build better varieties or cultivars.”

Knapp stated that a large driving force for their research was the work of young scientists from UC Davis and MSU who were involved in the study.

“There are a lot of authors, but a lot of really talented young people, early career people, who drove the innovation and the science here to make this happen,” Knapp said.

Written by: Michelle Wong — science@theaggie.org