e-mail:haughn @mail.ubc.ca
office phone: (604) 822-9089
lab phone: (604) 822-2437

Professor, Dept. of Botany
B.Sc. Biology (1978), Dalhousie Univ.;
Ph.D. Genetics (1985) Cornell Univ.;
Postdoctoral Fellow (1985-1987) MSU-DOE Plant Research Laboratory;
Assistant Professor of Biology (1987-1990), Univ. Saskatchewan;
Associate Professor of Biology, (1990-1993), Univ. Saskatchewan.

Haughn Lab Website

Research Interests:
My laboratory uses molecular genetics to study the mechanisms regulating morphogenesis and differentiation in Arabidopsis.

1. Mechanisms underlying cell differentiation. The seed coat is a specialized tissue derived from ovule integuments. In some species, including Arabidopsis thaliana, large quantities of polysaccharide mucilage (pectin) and secondary cell wall are produced by seed coat epidermal cells at specific times during differentiation. Because these modifications are not required for viability, the Arabidopsis seed coat epidermal cells represent a unique dispensable tissue that can be used to identify genes involved in complex polysaccharide biosynthesis and secretion (Haughn and Chaudhury, 2005), important processes about which relatively little is known. As a first step to develop this unique model system we investigated the structure and differentiation of Arabidopsis seed coat secretory cells including the synthesis, secretion and extrusion of mucilage (Western et al., 2000). We next isolated a number of mutants defective in the differentiation, synthesis and extrusion of mucilage (Western et al., 2001). Our cloning of one of these, MUM4 (Western et al., 2004) identified a key pectin biosynthetic enzyme that proved to be an important tool for dissecting the network of transcription factors regulating differentiation of the seed coat epidermal cells and for isolation of additional mutants through modifier screens. Our recent cloning and characterization of the MUM2 gene (Dean et al., 2007) has shown that it encodes a B-galactosidase required for modification of the mucilage to allow for its normal hydration properties. This gene therefore establishes an important link between a specific enzymatic reaction and alteration of the chemical physical properties of pectin that may play roles in other processes like fruit ripening and cell wall loosening during growth. Since mucilage is primarily pectin and pectin is secreted from cells we characterized the secretory apparatus during differentiation of the seed coat epidermis. We demonstrated that mucilage is indeed secreted through the Golgi and that during the transition into the mucilage secretory phase there are dramatic changes to the Golgi morphology and number (Young et al., 2008). Current projects include microarray analysis of seed coat differentiation, cloning and characterizaytion of the MUM1gene, genetic modifier analysis of MUM4 and MUM2, identification of seed coat specific promoters, expression of recombinant proteins in the epidermal cells and development of analytical techniques for the rapid determination of pectin structure.

2. Control of Plant Morphogenesis. During morphogenesis three separate developmental axes must be specified to elaborate morphology: abaxial-adaxial, proximal-distal and central-lateral. We recently identified and partially characterized two important genes, BOP1 and BOP2, that play key roles in the establishment of proximal-distal symmetry in leaf and floral morphogenesis. The two BOP genes encode redundant regulatory proteins with high sequence similarity to the well-characterized protein NPR1. NPR1 functions as a key regulator of systemic acquired pathogen resistance. A systemic signal of pathogen attack (salicylic acid) activates NPR1 post- translationally allowing it to function as a transcription factor. Our current evidence suggests that BOP functions in a manner similar to NPR1 (Hepworth et al., 2005). We have also characterized the abscission-related function of BOP demonstrating that it is needed to promote development of the abscission zone cells (McKim et al, 2008). We continue to investigate the mechanism of BOP function.

3. TILLING. TILLING (Targeted Induced Local Lesions in Genomes) is a powerful technique that can identify a series of allelic mutations or SNPs in a target gene by heteroduplex analysis (Till BJ, et al. 2003, Genome Res. 13:524-530; Gilchrist and Haughn, 2005). It can be adapted for use in a high-throughput facility, and has been successfully applied to many plants and animals. Beginning in 2002 we established a TILLING facility, CAN-TILL ( http://www.botany.ubc.ca/can-till/ ) at UBC. We are in the process of developing a TILLING service in Canada that will be able to identify mutations in genes from a wide variety of different organisms. To date we have successfully TILLED in Arabidopsis thaliana, Caenorhabditis elegans (Gilchrist et al., 2006B), and Brassica oleracea (manuscript in revision) and we are currently testing this technique in Brassica napus as part of the Genome Alberta/Genome Canada project Designing Oilseeds for Tomorrow's Market. We have also used TILLING to look at natural variation in Populus trichocarpa (known as EcoTILLING; Gilchrist et al., 2006A). We are always in search of partners to develop TILLING populations in other organisms.

Research Team:
Erin Gilchrist (Research Associate)
Abdul Ahad (Research Associate)
Jun Huang (Graduate Student, PhD)
Robin Young (Graduate Student, PhD)
Sarah McKim (Graduate Student, PhD)
Yuanyuan Yu (Graduate Student, MSc)
Jonathan Griffiths (Graduate Student, PhD)
Zhaoqing Jin (Graduate Student, PhD)
Tanya MacInnes (Technician)
 

Western, TL, DJ Skinner & GW Haughn. (2000). Differentiation of mucilage secretory cells of the Arabidopsis thaliana seed coat. Plant Physiology 122: 345-355.