1. Comparative mapping of the Oregon Wolfe Barley using doubled haploid lines derived from female and male gametes
L. Cistue, A. Cuesta-Marcos, S. Chao, B. Echavarri, Y. Chutimanitsakun, A. Corey,
T. Filichkina, N. Garchia-Marino, I. Romagosa, P. M. Hayes

2. Rationale/Goals
Aimed to increase the Oregon Wolfe Barley population size to create a more useful linkage map
Great resource, particularly for Barley research
Barley is an economically important plant
Aimed to study differences in creating linkage maps from doubled haploid populations with different sources (female vs male gametes)
Increased population size better for QTL mapping

3. Introduction
Previous population doubled haploids from female gametes (H.b.) – 82 unique individuals
A number of different types of molecular data were used on linkage map for this population
RFLP, AFLP, SSR, DArTs, SNPS, RADs
Created population of doubled haploids from male gametes (A.C.) – 93 individuals
Combined population – = 175

4. OWB Dominant Parent
OWB Recessive Parent

5. Materials and Methods Create linkage map using molecular markers
SNP markers (total of 1,328 polymorphic markers)
Created linkage maps for the A.C. population, the H.b. population, and the combined data set
Phenotypes
Grew plants in greenhouse and measured a number of characters important to barley growers
QTL Mapping
QTL = quantitative trait locus
Links phenotype with genotype
Finding the locus (or loci) that control a phenotypic trait

6. Results
All the loci are in the same order!

7. Results
Why would we see different numbers of crossovers between these two populations?
Because male and female gametes may have different rates of recombination (one reason that this study was done with male gametes – to see if this was true)
Because the two populations were derived from different meiotic events, and one would expect some level of variability
Recombination rate is 1.78 in A.C., 1.72 for H.b.
So, pretty darn close

8. Results
Female Gamete
What is the expected dominant allele frequency in this population?
What are the different dashed lines?
What does it mean if the peak is over the dashed lines?
Male Gamete
0.5 – same for recessive
Different confidence levels
Way to avoid calling false positives
Combined
Segregation distortion – genotype frequencies NOT what expected

9. Results Main takeaway:
Segregation distortion was higher in the A.C. population
Regions on 3H and 5H correspond with areas found to control phenotypes that could have affected a plant’s ability to survive the A.C. process
Region on 2H corresponds with ZEO-1, a dominant dwarfing allele.
Perhaps when ZEO-1 was dominant, the plants did not survive, so the study did not see their alleles in the population.

10. QTL mapping = connecting phenotype to genotype
Shows positions on the chromosome (in cM) where QTLs, or the region controlling traits, are found. The peaks also map to the same place as known genes VRS1 and ZEO1
The peaks are not straight lines at a single position because of linkage
These genes are pleiotropic – seen in multiple peaks aligned with each gene

11. Conclusions
Some differences between populations from male and female gametes, but both would be suitable for linkage map studies
Recombination rate slightly higher in A.C. population
Higher segregation distortion in A.C. population, but not due to production method
Gained further insight into relationships between genotype and phenotype and what loci control which phenotypes
Successfully created a larger population of OWB doubled haploids for future studies

13. Generate F1 progeny
Make doubled haploids from pollen of progeny
B B b
Bb Bb
Plant two seeds per individual to phenotype in greenhouse
Plant grows and produces seed
BB or bb genotype