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Advances in biotic and abiotic stress tolerance
1. Background, and why I am here Insect resistance in Arabidopsis Epistasis and growth rate Insect resistance in the field Approaches to drought tolerance in rice Thomas Mitchell-Olds Institute for Genome Sciences & Policy Department of Biology Duke University [email_address] Advances in biotic and abiotic stress tolerance
2. University of Wisconsin : Ph.D. in Botany; Plant Breeding & Plant Genetics Postdoc in Human Genetics
6. Why am I here? 1) Research to benefit human welfare 2) Rice is similar to Arabidopsis 3) Phenotypes in the field 146 276 150 Undernourished population in millions
8. Correspondence of QTLs for insect resistance & glucosinolate levels Insect Resistance in Arabidopsis LOD score Insect resistance Position on Chromosome V Position on Chromosome V Glucosinolates R S-Glucose NOSO 3 -
9. Myrosinase Other products Thiocyanates (RSCN) Nitriles (RCN + S) Isothiocyanates (RNCS) R S-H NOSO 3 - Insect resistance and chemical defense R S- Glucose NOSO 3 - Arabidopsis glucosinolates: From amino acid precursor Influence insect resistance Genetically variable Evolve non-neutrally Breakdown of glucosinolates leads to toxic products
10. Cloning QTL for insect resistance and glucosinolates LOD score Position on Chromosome V Position on Chromosome V Initial QTL mapping Fine scale mapping of GS QTL Positional cloning Verification by transformation QTL cloning is easier for secondary traits (like GS) than for insect damage or yield under drought Insect resistance Glucosinolates
11. MAM2 gene controls Kroymann et al . 2003 PNAS glucosinolate concentration & resistance to generalist herbivores but not specialist herbivores, and does not impact growth rate
12. Why are complex traits polymorphic? Data come from cloned QTLs Hence no information on small effect QTL Growth rate QTL in Arabidopsis thaliana Kroymann & Mitchell-Olds, Nature, 2005 Epistasis and growth rate Juergen Kroymann
13. Growth rate QTL in the MAM region 0 1 2 3 4 5 6 7 8 0 25 50 75 100 125 150 175 200 225 250 0 1 2 3 4 5 6 7 8 0 25 50 75 100 125 150 175 200 225 250 F ratio 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 0 25 50 75 100 125 150 175 200 225 250 position [kb] MAM2 gene does not impact growth rate
14. 0 25 50 75 100 125 150 175 200 225 250 0 1 2 3 4 5 6 7 8 0 25 50 75 100 125 150 175 200 225 250 F ratio 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 0 25 50 75 100 125 150 175 200 225 250 position [kb] Two Growth rate QTL in the MAM region 0 1 2 3 4 5 6 7 8 Right QTL: gr Left QTL: gl - 0.06 - 0.03 0 0.03 0.06 Mass (L er - Col) [mg] - 0.06 - 0.03 0 0.03 0.06 Mass (L er - Col) [mg] - 0.06 - 0.03 0 0.03 0.06 Mass (L er - Col) [mg] Tightly linked QTL show opposite effects Ler > Col Col > Ler
23. Genus Boechera (formerly Arabis) Close relative of Arabidopsis Genome ~ 250 Mb Positional cloning Transformation Undisturbed natural populations Diploid apomixis
24. Resistance variation in Boechera stricta 0 20 40 60 80 100 Percent Leaf Damage 0 20 40 60 80 100 Frequency Trichoplusia ni
25. Glucosinolate quantity in Boechera stricta About 30% of variation is under genetic control
26. BCAA: branched chain amino acids: Val, Leu, Ile 0.0 0.2 0.4 0.6 0.8 1.0 Proportion of GS from BCAA 0 10 20 30 40 50 60 Frequency Glucosinolate type in Boechera stricta Met-GS BC-GS Met allele is more resistant BCMA locus: Branched Chain Methionine Allocation T. ni : generalist herbivore BCMA controls resistance to generalist herbivore
30. Susceptible BC allele Resistant Met allele N = 2,032 plants; 47,109 leaves CO MT 0 5 10 15 Percent Leaf Damage High herbivore pressure Lower herbivore pressure
31. ANOVA: significant natural selection in the wild, P < 10 -9 Colorado: Herbivory reduces survival Montana: No natural selection on herbivore resistance Survival 993 plants in Colorado Selection gradient: 1% of leaf area removed reduces fitness by 1.1% How does insect resistance influence fitness? How does insect resistance influence fitness? How do secondary traits influence yield under drought?
32. Susceptible BC allele Resistant Met allele Strong selection for resistance No selection for resistance CO MT 0 5 10 15 Percent Leaf Damage High herbivore pressure Lower herbivore pressure
33. BCMA summary Positional cloning of BCMA Influence of trait on fitness in field environment
34. Approaches to drought tolerance in rice 1) Yield in managed stress environments 2) Trait dissection into component traits
35. Benfey lab Duke Univ Nondestructive, automated analysis of root architecture 360 degrees using computer controlled motorized turntable
38. Approaches to drought tolerance in rice 1) Yield in managed stress environments 2) Trait dissection into component traits 3) Dissecting drought environments Develop laboratory models of drought environments Understand their effects on drought tolerance Quantify axes of environmental variation Photo by J. Lamo & O. Michael
39. Ruiz Corral, et al. 2008, Crop Sci 48: 1502 Different maize races are grown in different environments Quantify axes of environmental variation Environmental Conditions PC1 Environmental Conditions PC2 Shapes indicate genetic groups
40. Hypothetical example: environmental dependence of drought tolerance Plot nurseries based on environments Measure yield advantage at each site 3D plot: yield advantage vs. environment Grow NILs in multiple environments
41. Hypothetical example: environmental dependence of drought tolerance Develop laboratory models of drought environments What aspects of the environment control the yield advantage?
42. Approaches to drought tolerance in rice 1) Yield in managed stress environments 2) Trait dissection into component traits 3) Dissecting drought environments 4) Integrated pedigrees for QTL & association analysis - Cannot use association approach for traits that differ between indica, japonica, or other groups - Epistasis is a major problem for association studies
43. Bao-Hua Song Kasavajhala Prasad Antonio Manzaneda Carrie Olson-Manning Philip Benfey Eric Schranz Aaron Windsor Juergen Kroymann Maria Clauss Karl Schmid Dan Kliebenstein Jonathan Gershenzon Kathy Springer Toyin Aremu-Cole Molly Mitchell-Olds Sara Mitchell-Olds Janoo Naqvi Slater Hurst Michael Cameron J. Lutkenhaus Laura Saucier Elizabeth Ballweg Cheng-Ruei Lee Antje Figuth Susi Donnerhacke Kerstin Weniger Sylke Dietel Marion Kupper Sylke Dietel Grit Schubert Katja Schwarzer Nancy Richter D. Schnabelrauch Tabea Birk Kerstin Weniger NSF NIH Duke MPG