Christie Williams

Assistant Professor (Adjunct) USDA-ARS, Research Molecular Biologist
 
Office Phone: 494-6763
Office Number: WSLR 236
Lab Number: WSLR 241
Office Phone: 494-0183
Email Address: cwilliams@purdue.edu


Education

PhDGenetics


Professional Background

University of California, Berkeley, Ph.D. in Genetics, 1987.
University of California, Davis, B.S. in Genetics (with Honors), 1976.

Professional Experience:
Purdue University Department of Entomology, Assistant Professor-Adjunct and USDA/ARS Research Molecular Biologist, 1995-present.

University of California, Davis, Department of Plant Pathology, Postdoctoral Researcher, 1992-1995.

University of California, Davis, Department of Vegetable Crops, Postdoctoral Researcher, 1991-1992.

University of Wisconsin, Madison, Department of Plant Pathology, Research Geneticist USDA/ARS, 1987-1990.

University of Hawaii, Manoa, Department of Plant Molecular Physiology, Postdoctoral Researcher, 1985-1987.
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Professional Associations

Sigma Xi Scientific Research Society, International Society for Plant Molecular Biology, International Triticeae Mapping Initiative, Ohio Valley Entomological Association, American Society of Plant Biologists ô


Research Interests

Host-plant ResistanceMolecular genetic basis of resistance in wheat to the Hessian fly


Professional Activities

A) Identification of defense-related genes.
Goal: Identify wheat genes induced during the interaction with the Hessian fly.

Little is known about the biochemical basis of wheat/Hessian fly interactions. In other plants that mount a gene-for-gene response to bacteria, viruses or fungi, genes are induced that are considered characteristic of a hypersensitive response and a signal transduction pathway. These are not the primary resistance genes that initiate a signal transduction cascade, but are downstream genes directly involved in defense. Often, during a compatible interaction, the same genes are induced much later than during an incompatible interaction. We are identifying RNA species that differ in timing and level of induction during compatible and incompatible interactions. H9-containing wheat plants are being challenged with either virH9 Hessian fly (compatible) or virH6 fly (incompatible). Subtraction methods are being used to remove all mRNA species that are common to infested and uninfested plants. The induced mRNA are being cloned, sequenced and analyzed to determine whether they are homologous to data-base sequences that are associated with resistance in other plants. We are currently working with 40 partial cDNA clones that appear to be differentially expressed in wheat in response to Hessian fly feeding. Stress-response genes, similar to sequences from other species, are among the wheat sequences that have been isolated. Some of these clones that we have isolated are similar to: Triticum aestivum cDNA clone from etiolated seedling root, NADH dehydrogenase ND1 [Triticum aestivum], Secale cereale cDNA from cold stressed winter rye seedlings, Member of the PF|00955 Anion exchanger family [Arabidopsis thaliana], Putative cinnamyl alcohol dehydrogenase [Malus x domestica], Glucose acyltransferase [Solanum berthaultii], Putative pumilio/Mpt5 family RNA-binding protein [Arabidopsis thaliana], Bacterial blight resistance protein Xa1-like protein [Oryza sativa]. Other cDNAs that we have isolated are unique and have never before been implicated in a stress response.


B) Characterization of Hfr-1 expression.
Goal: Identify environmental conditions that induce the expression of this gene.

The gene described in “C” below responds with increased expression to avirulent first-instar Hessian fly larval feeding. We are determining whether that expression is specific to Hessian fly infestations or whether it is a general stress response. Plants have been subjected to wounding, dessication, and treatment with Methyl Jasmonate, Salicylic Acid, BTH and ABA. We have shown that Hfr-1 is induced only by Salicylic Acid and BTH, suggesting that it is a specific response to Hessian fly and the induction of defense response pathways used to combat microbial infections. BTH is able to induce mRNA levels of Hfr-1 to 80 times the uninfested level. Hessian flies induce the mRNA about 8 fold.Although SA causes increased expression of Hfr-1, SA does not induce resistance to Hessian fly. Thus additional pathways must be involved in resistance. The level of mRNA is independent of the number of larvae that are on a plant. But the increase in mRNA is much higher near the larval feeding sites than in the leaves, although the message is induced systemically in the plant.

C) Characterization of Hfr-1 mRNA
Goal: Determine the molecular class of the deduced protein.

Blast analysis indicates that the protein encoded by Hfr-1 is very similar to a mannose-binding jacalin-like lectin. The amino acid sequence contains all 12 of the amino acids that are invariant among all proteins known to function as mannose-binding jacalin-like lectins. These amino acids are necessary for the beta-prism fold structure of the protein. This class of lectins is quite divergent in all other amino acids in the lectin domain, allowing a great diversity in substrates. Our collaborator in Belgium (Els Van Damme) has determined that our BTH-treated wheat plants have a greatly increased level of a protein that has mannose-binding jacalin-like lectin activity.

D) Genomics of resistance
Goal: to identify wheat cDNAs that respond to infestation and infection.

In collaboration with the company CuraGen, our lab along with 3 other wheat labs on campus has constructed about 50 cDNA libraries from plants undergoing compatible and incompatible interactions with Hessian fly, scab and Septoria fungus and Barley Yellow Dwarf Virus. CuraGen is using its patented “gene calling” system to identify and compare cDNAs that are in common among all of the diseases and cDNAs that are unique to each interaction.

E) Proteomics of resistance
Goal: to identify proteins that respond to infection and infestation.

In collaboration with 4 other labs on campus, we are using tandem mass spectroscopy to identify phosphorylated peptides that change in abundance during compatible and incompatible interactions. Our first test case is an incompatible interaction between wheat and Septoria fungus. Several peptides have been identified and are currently being sequenced.


Completed Projects:

A) Predicting the success of wide crosses, based on a marker for the hybrid sterility locus of rice.
Goal: Provide a PCR-based marker, for use in marker-assisted breeding, that will allow early detection of fertile individuals in wide crosses.

Exploitation of crosses between the japonica and indica subspecies of rice is hindered by hybrid sterility. However, germplasm containing the S-5n wide compatibility allele, derived from tropical japonica (javanica), can be used as an intermediate in the transfer of traits. A PCR-based DNA marker, STS213, was designed and used to identify the fraction of an F3 population, segregating for S-5n and the japonica allele S-5j, that was most likely to yield fertile progeny from crosses with indica rice. Plants carrying the STS213 allele associated with wide compatibility, had significantly higher fertility than plants containing the japonica allele. The ability to detect seedlings bearing S-5n, the wide-compatibility allele, will facilitate the introgression of this allele into temperate japonica cultivars while eliminating the need to test cross, self and score for fertility a majority of the individuals during introgression.

B) Molecular markers for a new wheat gene conferring resistance to the Hessian fly. This was the masters work of C.C. Collier and resulted in a manuscript that is in preparation.
Goal: To provide Sequence-tagged sites that will aide in the introgression of a new, robust resistance gene into a pyramided germplasm line.

The new resistance locus (temporary designation = Hf5), derived from durum wheat, was characterized to determine that 1) it did not correspond to a previously known gene and 2) that it was robust in both homozygous and heterozygous common wheat. Two tightly linked molecular markers were identified (AFLP) and converted into inexpensive, easy to use Sequence-tagged site markers (PCR based and specific to the resistance locus).

C) Identification of loci that respond to feeding by Hessian fly larvae.
Goal: Identify genes that may be associated with the signal-transduction pathways leading to insect resistance. This work resulted in a manuscript that is in preparation.

Through gene-for-gene interactions, wheat plants respond to specific biotypes of Hessian fly upon the initiation of larval feeding. Plants containing the H9 resistance gene responded to avirulent biotype L larvae with a rapid increase in Hessian fly-induced mRNA in their leaves. A gene whose expression was modulated by larval infestation was identified and a partial cDNA clone was isolated through differential display analysis. The full-length cDNA clone was identified through the use of the Genome Walker Kit. The expression of this gene (Whi-1; wheat Hessian fly-induced) increased for two days before returning to preinfestation levels by day five, correlating with the onset of resistance. Whi-1 mRNA levels did not increase in plants infested with virulent larvae. Both the kinetics of expression and the similarity of the partial cDNA clone to plant defense genes suggested a defense-related function. Blast searches indicated three conserved domains that correspond to various classes of Pathogenesis Response genes.

D) Identification of wheat Expressed Sequence Tags (ESTs). Partially in collaboration with Drs. Joe Anderson and Steve Goodwin, USDA-ARS.
Goal: Identify wheat genes that are highly expressed in young leaves.

We have cloned and sequenced over 1000 partial cDNA clones that are abundant in young wheat leaves. The presumed functions of the corresponding proteins are being determined by similarity to other sequences in the BLAST database. These EST sequences have been submitted to BLAST for inclusion in the web-accessible DNA sequence database

D) Search for new resistance genes
Goal: to use wheat disomic substitution lines to identify chromosomal regions from Lophopyrum elongata that contribute new resistance to insects and pathogens.

In collaboration with 3 other labs on campus, we screened 20 wheat disomic substitution lines for resistance to Hessian fly, scab powdery mildew and Septoria fungus and Barley Yellow Dwarf Virus. Strong resistance was found to scab and Septoria, with mild resistance to Barley Yellow Dwarf Virus. Because this work was done on substitution lines, we were able to identify which chromosomes of the donor species were involved.


Collaborations:

A) Hessian fly resistance genes in wheat.
Goal: Characterize eight new genes and whether they are allelic to other reported genes for Hessian fly resistance.

In cooperation with Dr. Herbert Ohm (Agronomy, Purdue University) we have constructed F2 mapping populations in order to determine the chromosomal locations of several new resistance genes. This information has been used in selecting which of the genes to combine into breeding lines. Tightly linked genes will be more difficult to combine initially, but will be easier to introgress. In addition. we have constructed di-allele crosses between the plants containing the new genes and between six cultivars that each contain deployed genes. So far we have shown that several of the lines contain unique new sources of resistance. The results will insure that we combine only genes that are non-allelic and which were not deployed previously.


B) Generation of ESTs from wheat seedlings
Goal: Identify, clone and sequence 1000 ESTs to serve as basis for generating database described in 7C. C. E. Williams, J.M. Anderson and S. B. Goodwin. Funded by Agricultural Genomics Initiative Grants –Purdue Univ. $5000. These EST sequences were submitted to the BLAST database, 2000.

C) Proteomics of Wheat Resistance.
Goal: Use Mass Spectrometer analysis to identify proteins whose abundance changes in response to microbial infection or Hessian fly infestation. Grant Proposal submitted by C. E. Williams, J.M. Anderson, H.W. Ohm, F. Regnier and S. B. Goodwin was funded by the Showalter Trust, 2000, $100,000.

D) Generation and characterization of a disease and pest-specific wheat EST database and microarrays.
Goal: Identify, clone and sequence 10,000 ESTs associated with resistance responses from various organs during disease and pest resistance. by C. E. Williams, J.M. Anderson Herb Ohm and S. B. Goodwin.

E) Dean’s Team Award, School of Agriculture, Purdue University, 2000
Awarded to the Purdue Small Grains Group for work in basic and applied research on wheat and oats and production of germplasm and cultivars that exhibit resistance to major diseases and pests (10 members of the team).


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Selected Publications

1. Williams, C. E. Woodman, J. C., Chen, C. H., Alleman, M. L., Johns, M. A. and Freeling, M. An annotated bibliography of the Adh genes of maize, from 1966 through 1981, and predictions on the future of classical genetics. pp. 145-153. In Maize for Biological Research, W. F. Sheridan (ed.). Univ. Press. 1982. (Book Chapter).

2. Williams, C. E. Organ-specific expression of alcohol dehydrogenase in Drosophila melanogaster and Zea mays. Ph.D. Dissertation in Genetics, University of California, Berkeley. 1987.

3. Williams, C. E., Hunt, G. J. and Helgeson, J. P. Fertile somatic hybrids of Solanum species: RFLP analysis of a hybrid and its sexual progeny from crosses with potato. Theor. Appl. Genet. 80:545-551. 1990.

4. Williams, C. E., Kloeckener-Gruissem, B. and Freeling, M. Naturally occurring variants of maize Adh-1 differ in organ-specific expression, both in quantity and developmental timing. Maydica 36:115-128. 1991.

5. Williams, C. E., Wielgus, S. M., Haberlach, G. T., Guenther, C., Kim-Lee, H. and Helgeson, J. P. RFLP analysis of chromosomal segregation in progeny from an interspecific hexaploid somatic hybrid between Solanum brevidens and Solanum tuberosum. Genetics 135:1167-1173. 1993.

6. Williams, C. E. and St. Clair, D. A. Phenetic relationships and levels of variability detected by restriction fragment length polymorphism and random amplified polymorphic DNA analysis of cultivated and wild accessions of Lycopersicon esculentum. Genome 36:619-630. 1993.

7. McGrath, J. M., Wielgus, S. M., Uchytil, T. F., Kim-Lee, H., Haberlach, G. T., Williams, C. E. and Helgeson, J. P. Recombination of Solanum brevidens chromosomes in the second backcross generation from a somatic hybrid with S. tuberosum. Theor. Appl. Genet. 88:917-924. 1994.

8. Williams, C. E. and Ronald, P. C. PCR template-DNA isolated quickly from monocot and dicot leaves without tissue homogenization. Nucleic Acids Res. 22: 1917-1918. 1994.
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9. Ronald P. C., Holsten T., Scambray J., Song W. Y., Wang G. L. and Williams C. E. Molecular genetic analysis of the rice bacterial blight resistance locus Xa21. In Plant Genome and Plastome: Their Structure and Evolution. K. Tsunewaki (ed.) pp 95-100. 1995. (Book Chapter).

10. Ronald, P. C., Song, W. Y., Wang, G. L., Chen, L. L., Kim, H. S., Pi, L. Y., Holsten, T. E., Ruan, R., Wang, B., Williams, C. E., Zhai, W. X., Zhu, L. H. and Fauquet, C. The rice disease resistance gene encodes a receptor kinase-like protein. Proceedings form the Third International Rice Genetics Symposium, Manila, Philippines, 16-20 October. 1995. (Conference Proceedings).

11. Ronald, P. C., Holsten, T., Scambray, J., Song, W. Y., Wang, G. L. and Williams, C. E. Molecular genetic analysis of the rice bacterial blight resistance locus, Xa21. In Rice Blast Disease. Ziegler, R S., Leong, S.A., and Teng, P.S.(eds.) 1995. (Book Chapter).

12. Williams, C. E., Wang, B., Holsten, T. E., Scambray, J., de Assis Goes da Silva, F. and Ronald, P. C. Markers for selection of the rice Xa21 disease resistance gene. Theor. Appl. Genet. 93:1119-1122. 1996.

13. Ratcliffe, R., Cambron, S., Maas, F., Williams, C., Jones, M., Liang, C. and Collier, C. Hessian fly. Annual Wheat Newsletter Vol. 42. 1996. (Technical Report).

14. Ratcliffe, R., Shukle, R., Williams, C., Cambron, S., Maas, F., Russel, V., Zantoko, L. and Collier, C. Hessian fly. Host Plant Resistance Newsletter. 1996. (Technical Report).

15. Williams, C. E., Yanagihara, S., McCouch, S., Mackill, D. and Ronald, P. Predicting success of indica/japonica crosses in rice, based on a PCR Marker for the S-5n allele at a hybrid-sterility locus. Crop Sci. 37:1910-1912. 1997.

16. Ratcliffe, R., Cambron, S., Maas, F., Williams, C., Jones, M., Liang, C. and Collier, C. Hessian fly. Annual Wheat Newsletter Vol. 43. 1997. (Technical Report).

17. Ratcliffe, R., Shukle, R., Williams, C., Cambron, S., Maas, F., Russel, V., Zantoko, L., Collier, C., Fasoula, D., Jones, M. and Liang, C. Hessian fly. Host Plant Resistance Newsletter. 1997. (Technical Report).

18. Williams, C.E. and Liang, C. Feeding of Hessian fly larvae on resistant wheat induces a gene homologous to a wheat gene activated by the SAR-inducung chemical BTH. In Proceedings of the 9th International Wheat Genetics Symposium. A. E. Slinkard (ed.) pp. 339-341. 1998. (Conference Proceedings).

19. Ratcliffe, R., Cambron, S., Maas, F., Gumaelius, L., Williams, C., Jones, M., Liang, C., Fasoula, D. and Collier, C. Hessian fly. Annual Wheat Newsletter Vol. 44. 1998. (Technical Report).

20. Ratcliffe, R., Cambron, S., Maas, F., Gumaelius, L., Williams, C. and Collier, C. Hessian fly. Annual Wheat Newsletter Vol. 45. 1999. (Technical Report).

21. Ratcliffe, R., Cambron, S., Gumaelius, L., Williams, C., Nemacheck, J., and Collier, C. Hessian fly. Annual Wheat Newsletter Vol. 46. 2000. (Technical Report).

22. Williams, C. E. Liang, C., Cambron, S. E., Nemacheck, J., and Collier, C. C. Wheat gene responding to feeding by avirulent first-instar Hessian fly larvae. In Proceedings of the 10th International Triticeae Mapping Initiative Workshop. pp.
10-12. 2000. (Conference Proceedings).

23. Harris, M. O., Williams, C. E. Ratcliffe, R. H., Stuart, J. J., Foster, S. P., Kanno, H., Morris, B. D., Rani, U., Shukle, R. H., Ohm, H. W., Pickering, R. A. and Griffin, W. Biology and host-plant relationships of the Hessian fly: past and current research. In: New Approaches to Gall Midge Resistance in Rice. J.S. Bentur (ed.). International Rice Research Institute, Los Banos, Philippines (in press). (Book Chapter).

24. Anderson, J. M., Ohm, H. W., Patterson, F. L., Sharma, H. C., Buechley, G., Goodwin, S. W., Huber, D., Perry, K., Shaner, G., Ratcliffe, R. H., Shukle, R., Williams, C. E., Cambron, S., Collier, C. C. and Stuart, J. Annual Wheat Newsletter Vol. 47. 2001. (Technical Report).

25. McGrath, J. M., Williams, C. E., Haberlach, G. T., Wielgus, S. M., Uchytil, T. F. and Helgeson, J. P. Introgression and stabilization of Erwinia tuber soft rot resistance into potato after somatic hybridization of Solanum tuberosum and S. brevidens. Accepted by Amer. J. Potato Res., July 17, 2001.

26. Williams, C. E., Collier, C. C., Nemacheck, J. A., Liang, C. and Cambron, S. E. A Wheat gene, related to defense-response genes and lectins, is systemically induced by attempted feeding of avirulent first-instar Hessian fly larvae. Accepted by J. Chem. Ec., Oct. 16, 2001.

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