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COLLEGE OF AGRICULTURE AND LIFE SCIENCES | ||
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Candace HaiglerProfessor of Crop Science and Plant Biology |
CROP SCIENCE
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4405 Williams Hall Box 7620 Raleigh, NC 27695 |
CURRICULUM VITAE | ||
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Candace_Haigler@ncsu.edu |
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The research in my laboratory centers on cellulose synthesis and the assembly of plant cell walls, particularly the secondary walls of cotton fibers and tracheary elements. Knowledge gained from these systems is expected to be applicable to improvement of cellulose biomass crops, such as wood, forage crops, and agricultural residues. An underlying theme of the research is the effort to achieve a better understanding of fundamental processes in plant biology as a foundation for production of value-added crops through genetic engineering or marker-assisted breeding.
Cellulose is the world's most abundant renewable material, and it exists with plant cell walls as crystalline fibrils. Its biogenesis is essentially a nanoscale structural manufacturing process with multiple levels of control (genetic, hormonal, biochemical, metabolic, cellular, and biophysical), and we still have much to learn about the details. We are especially interested in cotton fiber because, uniquely among plants, its secondary wall contains almost 100% cellulose. Cotton fiber is used intact for textiles and filler materials, and chemical cellulose purified from cotton fiber is a foundation for many industries.
We are interested in 21st century strategies to produce improved materials from cotton fiber, as well as in traditional quality parameters such as strength and fiber maturity. Our research is an integral part of the emerging transition to viewing cotton fiber, not as a bulk commodity, but instead as a higher value material grown from different genetic stocks for product-specific requirements.
Research in the Haigler lab is achieved through a unification of techniques including bioinformatics, genomics, molecular genetics, reverse genetics in the model plant Arabidopsis, fluorescence and electron microscopy, biochemistry, physiology, and plant transformation. Collaborators are sought whenever necessary to contribute expertise over this broad range.
A tracheary element of Zinnia elegans differentiating in culture; this cell system is used as a model for wood formation.
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Cotton fiber developing on cultured ovules is used in research on the molecular biology, biochemistry, and cell biology of cellulose synthesis.
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C. H. Haigler In Press. Substrate supply for cellulose synthesis and its stress sensitivity in cotton fiber. In: Brown RM Jr, Saxena I (eds) Cellulose: Molecular and Structural Biology, Kluwer Academic Publishers, The Netherlands
Haigler, C. H. 2006. Establishing the cellular and biophysical context of cellulose synthesis. In: T. Hayashi, ed. The Science and Lore of the Plant Cell Wall: Biosynthesis, Structure and Function, Universal Publishers: BrownWalker Press
Udall JA, Swanson JM, Haller K, Rapp RA, Sparks ME, Hatfield J, Yu Y, Wu Y, Dowd C, Arpat AB, Sickler BA, Wilkins TA, Guo JY, Chen XY, Scheffler J, Talierco E, Turley R, McFadden H, Payton P, Allen R, Zhang D, Haigler, C. H., Wilkerson C, Suo J, Schulze SR, Pierce ML, Essenberg M, Kim H, Llewellyn DJ, Dennis ES, Kudrna D, Wing R, Paterson AH, Soderlund C, Wendel JF. In press, 2006. A global assembly of cotton ESTs. Genome Research
Singh B, Haley L, Nightengale J, Kang WH, Haigler, C. H.,Holaday AS. 2005. Long-term night chilling of cotton, Gossypium hirsutum, does not result in reduced CO2 assimilation. Functional Plant Biology 32: 655-666
Haigler, C. H., Zhang, D., Wilkerson, C.G. 2005. Biotechnological improvement of cotton fiber maturity. Physiologia Plantarum 124: 285-294.
Roberts, A.W., Frost, A.O., Roberts, E.M., and Haigler, C. H. 2004. Roles of microtubules and cellulose microfibril assembly in the localization of secondary cell wall synthesis in developing tracheary elements. Protoplasma 224: 217-229.
Martin, L.K. and C. H. Haigler. 2004. Cool temperature hinders flux from glucose to sucrose during cellulose synthesis in secondary wall stage cotton fibers. Cellulose 11: 339-349.
Zhang, D., M. Hrmova, C.-H. Wan, C. Wu, J. Balzen, W. Cai, J. Wang, L.D. Densmore, G.B. Fincher, H. Zhang and C. H. Haigler. 2004. Members of a new group of chitinase-like genes are expressed preferentially in cotton cells with secondary walls. Plant Molecular Biology 54:353-372.
Mr. Utku Avci, Ph.D. student
Part of a Gossypium hirsutum cotton fiber viewed in the scanning electron microscope. Photo by M. J. Grimson, reprinted from: Cotton Fiber Development and Processing, An Illustrated Overview, R. Seagull and P. Alspaugh, eds., Cotton Incorporated, Cary NC and International Textile Center, Texas Tech University. 88 pp.
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A cross-section of a Gossypium hirsutum cotton fiber that was engaged in secondary wall deposition. The specimen was prepared by cryogenic fixation and viewed in the transmission electron microscope. Micrograph reprinted from Salnikov, V., Grimson, M.J., Seagull, R.W., Haigler, C.H. 2003. Protoplasma 221: 175-184.
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2) Cellular control of cellulose synthesis, including use of cryogenic and microwave-assisted methods for accurate preservation of cell structure and protein locations
A cross-section of a Zinnia elegans tracheary element differentiating in a suspension culture. The transmission electron micrograph is of a specimen fixed and embedded using
cryogenic methods, so that native protein location had almost no opportunity to change. The selective location of sucrose synthase at patterned sites of secondary wall thickening is indicated
by the colloidal gold tag after immunolocalization. This location for the sucrose synthase is consistent with a model for channeling of
UDP-glucose to the cellulose synthase. Micrograph reprinted from Salnikov, V.V, Grimson, M.J., Delmer, D.P., and Haigler, C.H. 2001. Phytochemistry 57: 823-833.
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A high magnification view in the transmission electron microscope of a Gossypium hirsutum cotton fiber in which sucrose synthase is located by the colloidal gold tag.
The enzyme is near the plasma membrane and the cortical microtubules, which is consistent with channeling of UDP-glucose to cellulose synthases embedded in the plasma membrane.
This study, which used cryogenic methods, established a technique to obtain reliable data about protein location
within secondary wall stage cotton fibers. Micrograph reprinted from Salnikov, V., Grimson, M.J., Seagull, R.W., Haigler, C.H. 2003. Protoplasma 221: 175-184.
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3) Metabolic control of cellulose synthesis, including its environmental sensitivity.
In seeking to address an agronomic problem in which cotton fiber cellulose synthesis is severely hindered by cool night temperatures (e.g. < 72°F or 22°C), we are interested in the metabolic control of cellulose synthesis. In collaboration with Dr. Scott Holaday and Dr. Bir Singh at Texas Tech University, we are analyzing a family of transgenic cotton plants with up-regulated sucrose phosphate synthase, which is expected to promote the synthesis of additional sucrose in heterotrophic cells to support cellulose synthesis. We also have other families of transgenic plants in progress through the work of Ms. Wendy Cai at Texas Tech University.
A metabolic diagram of a cotton fiber engaged in secondary wall cellulose synthesis. Reprinted from Haigler, C.H., M. Ivanova-Datcheva,
P. S. Hogan, V. V. Salnikov, S. Hwang, L. K. Martin, and Delmer, D.P. 2001. Carbon partitioning to cellulose synthesis. Plant Molecular Biology 47: 29-51.
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4) Development of tools for cotton biotechnology
To support future biotechnological strategies for modification of secondary wall deposition in cotton fiber, promoters to drive foreign gene expression at this stage are needed. We identified a gene that was differentially expressed in 18 DPA fiber during secondary wall deposition compared to 12 DPA fiber during primary wall deposition. Its promoter was isolated and fused to GUS and tested by stable transformation of cotton. The expression during secondary wall deposition in lint fiber was as expected, but there was also GUS activity in other cotton cells with secondary walls. In collaboration with co-authors on the manuscript (see figure legend), we determined that the corresponding protein resembled chitinases, but it was likely to lack hydrolytic activity while retaining chitin-binding activity. Other researchers showed that proteins in this family are required for cellulose synthesis, although their mechanism of action is unknown. Expression of this protein in cotton fiber supports the usefulness of the cell type for our ongoing work to identify novel participants in cellulose synthesis via genomic approaches.
GUS activity, reporting promoter activity, was observed from the onset of secondary wall deposition at ~16 DPA. GUS activity persisted for a long period of secondary wall deposition, until at least 40 DPA. Micrograph reprinted from Zhang, D., M. Hrmova, C.-H. Wan, C. Wu, J. Balzen, W. Cai, J. Wang, L.D. Densmore, G.B. Fincher, H. Zhang and C.H. Haigler. In Press. Plant Molecular Biology
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| POB 7620 Williams Hall NCSU, Raleigh, North Carolina, 27695 |
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(919)515-2647 MAIN OFFICE (919)515-7959 FAX contact_cropsci@ncsu.edu |