Determining Genes That Contribute to Wheat Grain Softness: Shantel Martinez
Year:
Junior
Major:
Bioengineering
Mentor: Lesley Murphy, Ph.D.,
USDA/ARS Wheat Genetics, Quality,
Physiology & Disease Research Unit
Geneticist (Plants)
Support: Auvil Fellows, GPSI
Fellowship, USDA/ARS Pac-West Unit, Washington Wheat
Commission
The end usage of wheat is determined by the softness of the flour after the grain is milled. This value is referred to as the Skcs value. For example, hard wheat is used in making breads and soft wheat is used for cakes. The genetic characteristic of grain softness is expressed on chromosome 5D, where the grain hardness (Ha) locus of wheat is located.
“My project is looking at a line of wheat that is softer than the average soft wheat,” says Shantel Martinez, a bioengineering major who has participated in USDA/ARS Wheat Genetics, Quality, Physiology & Disease Research Unit lab for two years. Martinez did her first research for a month in the summer of 2007 as an Upward Bound high school student from Omak. The lab team found her data so interesting they offered her a job when she became a Washington State University student.
The wheat used in Martinez’s lab was developed by crossing bread wheat with a related wheat species known as Agropyron. This resulted in a chromosomal translocation from the Agropyron to the bread wheat on chromosome 6A. “We call this line of wheat ‘Supersoft.’” According to Martinez this extremely soft wheat could make better cakes and cookies. Her goal is to determine why Supersoft wheat is so much softer than other wheat and whether there is a genetic component, other than the Ha locus, that is contributing to the increase in softness.
She uses a technique called Polymerase Chain Reaction (PCR) to discover which loci may be contributing to grain softness. In PCR, DNA is heated and split, allowing the primers to bind to the corresponding base pairs of DNA. When DNA is cooled, the primers anneal to the DNA strand, and an enzyme known as Taq polymerase begins DNA replication where the primers annealed to the DNA. Martinez’s SSR primers are designed to help genotype the entire wheat genome, focusing on Supersoft’s chromosome 6A.
After performing PCR, the DNA is then separated using acrylimide electrophoresis gels to create genotypic data. Gel electrophoresis is a technique used for the separation of DNA, RNA, or protein molecules using an electric current applied to a gel matrix. Martinez will then collect the phenotypic data and maps quantitative trait loci (QTL) with a computer program called QTL Cartographer. QTLs are stretches of DNA that estimate the locations of genes that underlie the trait in question. They also can be molecularly identified to help map regions of the genome that contain genes involved in specifying a quantitative trait. Martinez’s results from her initial data suggests a significant QTL for the Supersoft trait on the chromosome 6A.
.jpg)
Shantel Martinez inserting electrophoresis gels to create genotypic data.
Her mentor is Lesley Murphy, a geneticist with the USDA. “Shantel’s project is very large and ambitious,” comments Murphy, “but I am certain that she will produce a valuable body of work that has the potential to benefit wheat breeders that specialize in soft wheat production.”
Martinez’s undergraduate team research was depicted on a poster displayed at the 2009 Integrated Plant Sciences Retreat; she won the Best Undergraduate Poster award.
She hopes that her undergraduate research will “encourage both undergraduates and graduates to pursue research in plant genetics or anything else.”
Recently, Martinez received financial support from the Auvil Fellows program for two semesters to help continue her research project. She plans to publish her work and continue working in the lab until she graduates. Martinez also intends to get a Ph.D. and pursue a career in bioengineering research.
