RESEARCH INTERESTS:

Plant genetics and plant physiology have been my long-term research interests. I am a member of a national research team that developed the first soybean genetic map of 20 linkage groups (Cregan et al., 1999). That genetic map has now been upgraded to 1845 markers plus 150 classical markers (Song et al., 2004). We are currently working on using SNP markers to create a soybean transcript map. Molecular markers in the soybean map provide the means for identifying genomic segments - more commonly known as quantitative trait loci (QTLs) - that govern soybean traits such as yield or seed protein, and then allow breeders to introgress the favorable alleles at these loci into new varieties via marker-assisted selection. Indeed, my lab group recently used the soybean molecular marker map to identify, map, manipulate a QTL allele that increases soybean seed protein content by a substantive two percentage points (Chung et al., 2003). In more recent work, we used a selective genotyping technique to show that this allele for high protein is present in 37 or the 41 highest protein accessions in the soybean germplasm collection. Another of my primary research goals has been to make genetic improvement in soybean yield per se more rapid and effective via the introduction and use of modern genomic and molecular marker technologies to identify yield-determining traits. My lab was able to show that soybean yield response to water abundance and scarcity was linear. Moreover, we showed that the QTLs governing the response slope (i.e., water-use-efficiency, or WUE) were not different from those QTLs governing mean soybean yield per se at any level of water abundance or scarcity (Specht et al., 2001). I and my collaborators have recently embarked on research aimed at exploring the possibility of "mining" favorable alleles at yield QTLs from the wild relative of soybean (Glycine soja) for use in the cultivated soybean (Glycine max). However, we have also recently identified statistically significant (positive) transgressive segregants (TS) for yield in an elite x elite mating involving high-yielding northern x southern USA cultivars. Using molecular markers we plan to identify the parental, grandparental, and ancestral origin of the yield-enhancing QTL alleles that are responsible for this TS. This research is expected to provide significant insight on how breeders are able to continue to mine favorable genes from elite x elite matings.

COURSES TAUGHT:

• AGRO 896A (even-numbered years) Linkage Mapping and QTL Analysis.
• AGRO 896B (odd-numbered years) Plant and Crop Response to Abiotic Stress.

EXTENSION INTERESTS:

I have no extension appointment, but do serve as a scientific expert and liaison for soybean producers and their organizations at the State level (NSDUMB, NSA) and the National level (USB, ASA).

SELECTED PUBLICATIONS:

• Song, Q. J., L.F. Marek, R.C. Shoemaker, K.G. Lark, V.C. Concibido, X. Delannay, J.E. Specht, and P.B. Cregan. 2004. A new genetic linkage map for soybean. Theor. Appl. Genetics 109:122-128. (To get an electronic version of the map go to: http://bldg6.arsusda.gov/~pooley/soy/cregan/soymap.html )
  
  
• Purcell L. and J.E. Specht. 2004. Chapter 12. Physiological traits for ameliorating drought stress. pp. 569-620. In H.R. Boerma and J.E. Specht (eds.) Soybeans: Improvement, Production, and Uses. Agronomy 16. American Society of Agronomy. Madison, Wisc.
  
  
• VanToai, T.T. and J.E. Specht. 2004. The physiological basis of soybean yield and environmental adaptation. pp. xxx-xxx. In H.T. Nguyen and A. Blum. (eds.) Physiology and Biotechnology Integration for Plant Breeding. Marcel Dekker, Inc., New York, New York. (In press)
  
  
• Chung, J., H.L. Babka, G.L. Graef, P.E. Staswick, D.J. Lee, P.B. Cregan, R.C. Shoemaker, and J.E. Specht. 2003. The Seed Protein, Oil, and Yield QTL on Soybean Linkage Group I. Crop Sci. 43: 1053-1067.
  
  
• Staswick, P.E., Z. Zhang, T. E. Clemente and J.E. Specht. 2001. Efficient down regulation of the major vegetative storage protein genes in transgenic soybean does not compromise plant productivity. Plant Physiol. 127:1-8.
  
  
• Demirbas, A., B.G. Rector, D.G. Lohnes, G.L. Graef, P.B. Cregan, R.C. Shoemaker and J.E. Specht. 2001. SSR Markers Linked to the Soybean Rps Genes for Phytophthora Resistance. Crop Sci 41:1229-1227.
  
  
• Specht, J.E., K. Chase, M. Macrander, G.L. Graef, J. Chung, J.P. Markwell, M. Germann, J.H. Orf, and K.G. Lark. 2001. Soybean response to water: A QTL analysis of drought tolerance. Crop Sci. 41:493-509.
  
  
• Specht, J.E., D.J. Hume, and S.V. Kumudini. 1999. Soybean yield potential - A genetic and physiological perspective. Crop Sci. 39:1560-1570.
  
  
• Cregan, P.B., T. Jarvik, A.L. Bush, R.C. Shoemaker, K.G. Lark, A.L. Kahler, N. Kaya, T.T. VanToai, D.G. Lohnes, J. Chung, and J.E. Specht. 1999. An integrated genetic linkage map of the soybean. Crop Sci. 39:1464-1490.
  
  
• Chung, J., J. Lee, K. Arumuganthan, G.L. Graef, and J.E. Specht. 1998. Relationships between nuclear DNA content and seed and leaf size in soybean. Theor. Appl. Genet. 96:1064-1068.
  
  
• Lohnes, D.G. and J.E. Specht. 1997. Evidence for homoeologous linkage groups in the soybean. Crop Sci. 37:254-257.
  
  
• Shoemaker, R.C., K. Polzin, J. Labate, J. Specht, E.C. Brummer, T. Olson, N. Young, V. Concibido, J. Wilcox, J.P. Tamulonis, G. Kochert, and H.R. Boerma. 1996. Genome duplication in soybean (Glycine subgenus soja). Genetics 144:329-339.
  
  
• Akkaya, M.S., R.C. Shoemaker, J.E. Specht, A.A. Bhagwat, and P.B. Cregan. 1995. Integration of simple sequence repeat (SSR) DNA markers into a soybean linkage map. Crop Sci. 35:1439-1445.
  
  
• Shoemaker, R.C. and J.E. Specht. 1995. Integration of the soybean molecular and classical genetic linkage groups. Crop Sci. 35:436-446.