By Rachel Webber, College of Agricultural, Human and Natural Resource Sciences intern

Scientist Cameron Peace and lab
technician Terry Rowland.


Tests show some seedlings
have more chromosomes
Terry Rowland uses high-throughput machines to test extracted DNA from about 800 leaf samples at a time.
He runs the tests on about 2,000 samples a day and delivers the results to breeding programs. Last year, Rowland conducted an estimated 8,000 DNA tests during a three-month period.
He said an unexpected discovery was that some seedlings have three sets of chromosomes instead of two – just one example of the type of marker-indicated information that breeding programs can use. Kate Evans, director of the WSU apple breeding program, said the extra set of chromosomes usually results in a larger tree with bigger fruit and leaves.
PULLMAN, Wash. – With summer finally here, scientists in Washington State University’s horticultural genomics program are assisting their colleagues in WSU tree fruit breeding programs by providing DNA information about traits desirable – or not – for growers.
Finding genes associated with desirable traits has been compared to the proverbial needles in haystacks, but marker-assisted breeding techniques developed by WSU’s horticultural genomics program make the search manageable.
Using state-of-the-art technology (see accompanying story), lab technician Terry Rowland looks in leaf samples for indicators within the DNA that predict the cultivar’s flavor, texture, size, disease resistance, health-benefiting properties, or other profit-bearing characteristics.
“Sweet cherry and apple seedlings have already germinated (for the year) and are eagerly offering up their first leaves,” said Cameron Peace, program leader and assistant professor of horticulture.
Pinpointing specific traits before the fruit trees mature results in substantial financial savings. The program’s service allowed WSU researchers to more efficiently use $87,000 for the apple and cherry breeding programs in 2010.
Once a new cultivar is developed, growers need to be convinced it is worth adopting. The breeding programs use the genetic information to determine what qualities to keep in apples or which to pair with another trait for better taste, texture or storability.
Genetic information can be used to describe which cultivars can be compatibly planted to ensure a good fruit set, as well as the potential to produce high quality fruit and be self-fruitful (capable of setting a crop of self-pollinated fruit).
“The idea is that if growers know which new cultivars are genetically superior, they are more likely to produce the fruit commercially,” Peace said.
Learn more about WSU’s interdisciplinary research efforts to breed new fruit varieties by visiting