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Susan J. Lolle Purdue University National Science Foundation

Will that be allele cache or Mendelian credit? Evidence for the inheritance of ancestral sequences in Arabidopsis. Susan J. Lolle Purdue University National Science Foundation. Fusion mutants. Arabidopsis wild-type.

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Susan J. Lolle Purdue University National Science Foundation

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  1. Will that be allele cache or Mendelian credit? Evidence for the inheritance of ancestral sequences in Arabidopsis. Susan J. Lolle Purdue University National Science Foundation

  2. Fusion mutants Arabidopsis wild-type

  3. FIDDLEHEAD defined a class of mutations that resulted in ectopic organ fusion

  4. Two heads are better than one...

  5. hothead - phenotype • Organ fusion • Pollen hydration on vegetative surfaces • Increased rate of chlorophyll extraction • Limited self-fertility hth-10

  6. All hothead mutations are recessive Both copies of the gene must have a mutation to reveal the mutant phenotype

  7. Fundamentals of Mendelian Genetics • Two alleles per locus • Alleles can be dominant or recessive • Alleles are stable from one generation to the next, whether or not they contribute to the observed phenotype

  8. Self-fertilizing versesCross-fertilizing

  9. Progeny should all be homozygous hothead 100% progeny parent Stable Inheritance

  10. But, some progeny are wild-type! 90% 10%

  11. Mechanism? Arabidopsis wild-type Fusion mutant ?

  12. Sequencing of HOTHEAD • All mutant alleles contain a single point mutation in the HOTHEAD gene • Columbia and Landsberg wild-type alleles very similar; Ws quite different

  13. Using Molecular Markers to Genotype Allele ‘A’ Allele ‘a’ PCR amplify (using specific primers) Restriction Enzyme Digestion Gel electrophoresis

  14. Does phenotype relate to genotype?

  15. Does phenotype relate to genotype?

  16. What does the sequence tell us?

  17. I don’t know if this is such a wise thing to do, Bob.

  18. Is reversion really contamination?Is this a mistake? • Seed contamination due to wild-type plants grown in close proximity to mutants • Elevated levels of outcrossing in hothead mutants (who is the daddy?)

  19. Embryonic revertants • Revertants detected as embryos cannot be due to contaminating seed

  20. Explanations for Genetic Instability What does the sequence tell us? • Transposon-induced alleles • Inverted or direct repeats at the locus • Epigenetic alleles • High rate of random mutation • Gene conversion

  21. Gene conversion with other family members • None of these sequences could provide correction of the mutant nucleotide without introducing other changes HTH ACT GTT GGA ATT ACA hth-10 ACT GTT GAA ATT ACA At HTH-like 1GTT GTT GGG ATT ACC At HTH-like 2CCA CCTCAAGTTGTA At HTH-like 3CCA CCTCAAGTTGCA At HTH-like 4GTC GTG GGT GTT ACT At HTH-like 5GCC GTA GGA ATC ACC At HTH-like 6GCT GTT GGG ATC ACA At HTH-like 7GTC GTT GGA ATC ACA

  22. Instability of molecular markers in hth background

  23. Where did these sequences come from? • They were not present in the parental genome • molecular and genetic evidence • They were present in the ancestors • molecular and genetic evidence

  24. A DNA template cannot be detected in the parental genome Evidence strongly supports a ‘template-directed’ process. Is the template RNA? Where is it? How long does it persist?

  25. “@$#?!$” What might this mean? • Organisms could carry sequence information for more than two alleles • Mechanism might help self-fertilizing species avoid the negative consequences of inbreeding

  26. Should you worry about your ancestry? How long does the allele cache persist? Is it quality cache?

  27. National Science Foundation Acknowledgements People: Katie Krolikowski Ryan Lee Tina Nussbaum Wagler Liese Pruitt Trulie Thorley Mirayda Torres Jen Victor Jessica Young Collaborator: Bob Pruitt

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