Understanding Complex Traits in Maize through Structural and Functional Genomics

1. Understanding Complex Traits in Maize through Structural and Functional Genomics Georgia Davis

2. Structural genomics • Science related to discovery of gene order and organization across the genome.

3. Structural Genomics • Genetic mapping • Physical mapping • In situ hybridization

4. Functional Genomics • Science related to the discovery and definition of the function of genes C16 C18 C20 C22 C24 C26 Aldehydes Alcohols Wax Esters RNA Whole plant Cellular Biochemical

5. Trait analysis Gene disruption strategies Targeted Random DNA microarrays RNA profiling Protein chips Protein prediction algorithms Functional Genomics

6. Functional Genomics • Insect Resistance • QTL Analysis • Biochemical Pathway Identified. • Major QTL With Unknown Function. • Aflatoxin Reduction • QTL Analysis • Major QTL With Unknown Function. • One Biochemical Pathway Identified.

7. Fall armyworm • Present east of Rockies and South of Canada. • Eggadult in 4 weeks • One female lays several hundred eggs. • Broad host range

8. Hosts of Fall Armyworm

9. Southwestern Corn Borer • Narrow host range. • Mainly in southeastern US.

10. Southwestern Corn Borer Hosts

11. Germplasm Fall armyworm damage 10 days after infestation with 30 larvae per plant

12. Lepidopteran Resistance Beet armyworm Corn ear worm Fall armyworm Southwestern corn borer European corn borer

13. Juvenile traits • Dull epicuticular wax layer • Fatty alcohols • No leaf hairs • Adventitious roots present • No buliforme cells • Cells are rounded

14. Juvenile vs. Adult Leaves • Leaves maintain their phase status throughout development. • Number of juvenile leaves varies among inbreds. • A number of mutants in juvenile to adult phase change have been identified.

15. Summary of QTL Study gl15 1 2 3 4 6 7 8 9 10 5 27% 11% 59% 43% 66% 51% 7% SWCB FAW Juvenility

16. Gl15 • Apetala2-type transcription factor. • Regulates long-chain wax ester synthesis. • Controls epidermal juvenile to adult phase change.

17. Functional Genomics • Insect Resistance • QTL Analysis • Biochemical Pathway Identified. • Major QTL With Unknown Function. • Aflatoxin Reduction • QTL Analysis • Major QTL With Unknown Function. • One Biochemical Pathway Identified.

18. Hosts of Aspergillus flavus

19. Aspergillus flavus Infection via silk channel wounds in kernels cracks in kernels

20. Aflatoxin Aflatoxin B1 • Potent carcinogen. • Associated with liver cancer in humans.

21. Health concerns

22. Aflatoxin contamination • Large environmental influence. • Drought stress increases aflatoxin level. • Correct genes in both fungus and host required for high levels of toxin formation. • Synthesis is biochemically similar to anthocyanin biosyntheis in maize.

23. Aflatoxin QTL Summary D A A D Mp313Efavorable allele Va35 favorable allele

24. Anthocyanin vs. aflatoxin c1-n bz2 a2 a1 sh2 a2 bt pr in1 su c2 bz1 23X  toxin c1-p pr sh bz wx c2 7X  toxin a1 9X  toxin C2I-df r-g c sh wx

25. Functional Genomics C16 C18 C20 C22 C24 C26 Aldehydes Alcohols Wax Esters RNA Whole plant Cellular Biochemical

26. Summary • Structural genomics provides the tools needed to support functional genomics. • In plants, future technological advancements in the areas of protein-protein interactions and site-specific knockouts on a genome-wide scale are needed.