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Singer Lab Group

We are interested in the development and evolution of flowering in legumes. Our work is focused on two species, Pisum sativum (garden pea) and Chamaecrista fasciculata (partridge pea).

We are interested in inflorescence architecture in pea because it has a significant effect on yield. In an evolutionary context it is fascinating that highly conserved genes create diverse floral architecture among species and families of plants. Specifically we are characterizing genes that affect the complexity of reproductive branching in the garden pea that also affect flowering in other species.

We use a candidate gene approach to identify mutants in pea that are homologs of cloned genes in Arabidopsis, explore genetic interactions, and develop a model of the genetic regulation of flowering in pea. The long-term goals of our research program are two-fold. First, genetic manipulation of inflorescence architecture can increase yield. The second aim is to understand the evolution of floral and inflorescence developmental pathways in the legumes using our pea model as a springboard. Comparisons with Arabidopsis are helpful, but the families are too distant to fully address evolutionary questions. Funded by 0422840.

Our work with Chamaecrista utilizes whole transcriptome analysis of developmentally sequenced shoot, root, and nodule tissue. Along with colleagues Jeff Doyle (Cornell), Greg May (NCGR), and Steven Cannon (Iowa State), we are using comparative genomics to understand the evolution of flowering in the legumes as well as the evolution of nodulation and polyploidy. Currently we are looking at 30 Chamaecrista ecotypes to investigate genetic variation contributing to variation in flowering time. Funded by NSF 0746571.


Lab Group Members (1986-Present)

Senior Research Scientist

Postdoctoral Associates

  • John Sollinger (1994-1999) - Currently an assistant professor of biology at Southern Oregon University
  • Sonja Maki (1989-1994)

Research Technicians

  • Heidi Mullen (1990-2008)
  • Scott Moses (1989-1990)
  • Sarah Huber (1988-1989)
  • Cole Hannon (1987-1988)

Undergraduate research colleagues

  • Shanna Yang (14) - L-systems modeling of broccoli inflorescences
  • Jorde Ranum (’15) – Temperature effects on Chamaecrista flowering time
  • Stephanie Kravitz (’13) – Comparisons of Chamaecrista flowering time in three Minnesota prairie remnants
  • Ben Bedore (’13) - Genetic diversity in Chamaecrista populations in two Minnesota prairie remnants
  • Dhilhan Marasinghe (’14) – Genetic diversity in Chamaecrista populations in two Minnesota prairie remnants
  • Ned Heckman (’13) – Analysis of student models of gene x environment flowering time interactions
  • Raghav Changdra (’14) – Circadian expression of FT in Chamaecrista under short day conditions.
  • Anna Brezney (’13)  – Population genetics structure of Weaver Dune and McKnight PrairieChamaecrista
  • Lindsay Guthrie (’13) – Population genetics structure of Weaver Dune and McKnight Prairie Chamaecrista
  • Sarah Carter (’13) – SVP and flowering time in Chamaecrista, Carleton Science Fellow
  • Ian Hollyer (’13) – FVE and flowering time in Chamaecrista
  • Rachel Gottesman (’12) – FT and flowering time in Chamaecrista
  • Cameron Stahl(’14) – Investigating chitinase activity in  Sarracenia leucophy in the absence of symbionts
  • Meera Sury (’14) – Genetic diversity of Weaver Dune and McKnight Prairie Chamaecrista
  • Emma Singer (Mount Holyoke College ’14) – Expression of flowering genes in prairie-grown Chamaecrista
  • Marika Xydes Smith (’13) – Expression of flowering genes in prairie-grown Chamaecrista, Carleton Science Fellow
  • Madelyn Lehnard (’12) – Developmental regulation of photoperiod genes in Chamaecrista
  • Kristine Nachbor (’12) – Effect of photoperiod on flowering in Chamaecrista
  • Anna Snyder (’11) – Expression of temperature-dependent flowering genes in Chamaecrista
  • Kyla Walter (’11) – Expression of autonomous pathway flowering genes in Chamaecrista
  • Kelly Mayo (’11) – Characterization of the COCH homolog in Chamaecrista
  • May Dixon(’11) – Sequencing of the COCH homolog in Chamaecrista
  • Anna Newman ('11) - Analysis of LFY and KNOX1 expression in Chamaecrista 
  • Hunter Martin (’11) -  DNA barcoding of aster species in the Carleton Arboretum
  • Fang Yu Lee ('10) - Shoot transcriptome analysis in Chamaecrista
  • Danny Wells ('10) - Analysis of flowering gene expression in Chamaecrista vegetative and reproductive shoots using Solexa generated whole transcriptome sequences.
  • Kai Knutson ('11) - Analysis of the Chamaecrista transcriptome with JMP Genomics, Watson Fellowship awardee
  • Margaret Taylor ('10) - Testing VIGS constructs in peas
  • Viviann Chen (’09) – Programming bioinformatics tools in Perl, finishing second degree in engineering at Columbia
  • Emily LeGrand (’09) – Modeling interspecies defense responses to plant volatiles
  • Kim Morrell (’09) – Characterizing the 3’ end of Chameacrista homolog of PIM, graduate study, Cornell
  • Geoffrey House (’08) – 5’ RACE to identify 5’ end of Chameacrista homolog of PIM, graduate study in Water Resources Science at the University of Minnesota, Duluth
  • Zain Ali (’08)  - Constructing VIGS vectors for Chamaecrista, currently a research technician at Jackson Labs, Maine.
  • Liana Burghart (’07) – Real time PCR analysis of gene expression in pea, currently a research technician.
  • Anna Jolene Mork (’10) –Chameacrista homolog of PIM, recipient of a Barry M. Goldwater Scholarship
  • Jenna Forsyth (’07) – Sequencing the promoter region of PIM
  • Ron Hause (’07) – Genome walking to identify promoter region of PIM. Graduate school at the University of Chicago
  • Raven Bier (’07) – Genome walking strategies to identify promoter region of PIM
  • Anjuli Mishra (’07) – Chamaecrista homologs of pea inflorescence architecture genes, research technician
  • Tenzin Desa (’07) – Comparison of AP1 homologs in pea and Chamaecrista, graduate student at the Unviersity of Minnesota
  • Jayme Johnson (’06) – Virus-induced gene silencing to create phenocopies. Graduate studies at Duke
  • Kellie Carim (’06) – Asymmetry in purple coneflower populations.
  • Adam Williamson (’06) – Candidate gene approach to clone RUINOUS and COCHLEATA in pea. Graduate school at U.C. Berkeley
  • Adipong Brickshawana (’06) – Candidate gene approach to clone GRITTY in pea, graduate student at Mayo Graduate School
  • Julie VanderMeer (’05) – Cloning genomic peaFUL gene in pea, research fellow at NIH, graduate studies UCSF
  • Sarah Tilman (’05) – Morphological comparison of double mutants of PIM and different COCH alleles. Taught in Washington, DC (deceased)
  • Soren Peterson  ’05)- Cloning PeaFUL. Graduate studies at Stanford.
  • Lien Ly  (’04)– 3D analysis of branching in COCH mutants, graduate studies at Rutgers
  • Shaheynoor Talukder (’04)– Investigation of rotational transforms for branching in peas with asymmetric leaf morphology, masters degree in molecular biology from University of Toronto, then law school
  • Julie Nilsen Murphy (’04)– Application of L-systems using L-studio to modeling mutant peas, research technician, UC Santa Cruz
  • Suzanne Stock (’03)– Analysis of PIM expression in COCH mutants. Dental school in Iowa
  • Lindsay Calvert (’03)– Cloning COCH by putative homology with FUL, teaching students with learning disabilities.
  • Jessie Singer (‘07) – Investigation of rotational transforms for branching in peas with asymmetric leaf morphology. Graduate student, UC Berkeley (French Literature)
  • Dan Spieser  (’03)- Cloning PeaFUL from COCH mutants. Graduate studiest at Duke.
  • Melissa Dozier  (’03)– Analysis of redundant functions of COCH and PIM
  • Liz Addis (’02) -  Expression of PEAM9 using in situ hybridization. Graduate studies at University of Washington after work as a research technician at MIT
  • Kenechi Ejebe  (’02) – Transforming peas with Agrobacterium . Completed a research fellowship at the NIH, medical school at George Washington University.
  • Katherine Kleese (Grinnell student) – Transformation of pea using Agrobacterium. After graduating from Grinnell Katie took an environmental education position in northern Minnesota. PIRG coordinator in Portland Oregon. Audobon Nature Center in Minnesota.
  • Erin Boswell (’02)– Genetic analysis of multiflowering in pea. Masters in Public Health after a research fellowship at the CDC in Atlanta. In medical school.
  • Erin McKittrick (’01) - Erin is investigating the interaction between coch and pim. The double mutants have an almost complete inhibition of floral development.  Graduate school, University of Washington.
  • Katherine Fitzgerald (’01) – Asymmetery in COCHLEATA mutants (received honor in independent study, completed graduate study at Utah in mathematical biology, and is currently an ecology graduate student at Stanford.
  • Scott Haddock (’00) - Worked with Jane Bowen on sequencing of putative cloned genes (pea homolog of CEN in snapdragon).  Graduate studyl in genetics. Lab technician, virology
  • Brad Short (’00)- environmental effects/GA effects on pim. Teaching with Teach for America.
  • Ingrid Anderson (’99) - analysis of the coch mutant of pea that alters symmetry (SEM analysis). Ingrid is in graduate school at Indiana University.
  • Melissa Carlson (’99) - effect of gibberellic acid on the floral mutant, pim, of pea analyzed in the pim slender double mutant (slender increase gibberellic acid levels).  Melissa also investigated the effects of another gibberellic acid biosynthesis gene (LE) on pim.  Wilderness Ranger, US Forest Service.
  • Carey Sydney (’99)- experimental analysis of the coch mutant of pea (a mutation that gives the plant a true front and back!) to determine whether the gene is regulated by other flowering genes or is active during the vegetative phase of development.  Techniques include meristem culture, grafting, surgical manipulation of the meristem, scanning electron microscopy, and genetic analysis.
  • Laura Hopper  (’99)- analysis of the timing and location of the expression of the PIM gene in pea which is critical in assigning floral meristem identity.  Also continuing efforts to clone the pea homolog of the CEN gene from snapdragon which supresses terminal flower formation.  Clinical Research Coordinator, Americas Doctor.
  • Jane Bowen (’99)- Purification and sequencing of putative cloned genes (pea homolog of CEN in snapdragon).  Graduate studies– University of North Carolina, Chapel Hill
  • Jason Fischbach (’99)- environmental effects/GA effects on pim. Wilderness Ranger, US Forest Service.
  • Catherine Reinke (’98) - Transformation of pea with Arabidopsis genes.  Catherine took off winter term 1997 and worked full time on her project in the lab with the support of NSF REU funds that supplemented my grant.  Her research experience helped her obtain a summer 1997 position at Cornell.  She graduated from Carleton with degrees in English and Biology, has a Ph.D. from the University of Chicago was a visiting faculty member at Carleton. Currently a postdoc at Northwestern.
  • Josh Miner  (’98)- Protein purification for antibody production. 
  • Andrew McCall  (’98)- Investigated the evolution of branching patterns in legumes.  Andy was a Fulbright Fellow in New Zealand and earned a Ph.D. in ecology at U.C. Davis. Visiting faculty member at Carleton (2006), currently an assistant professor of biology at Dennison College.
  • Jim Crantz (’98)-  Expression of the pea homolog of AP1 in the common sepal/petal whorl of pea flowers.  Graduate studies in ecological modeling at the University of Michigan.
  • Sara Rubinstein  (’98) - Analysis of meristem termination in det uni double mutants of pea.  Currently a professional photographer.
  • Yewah Lau  (’98)- Analysis of segregation ratios of crosses of two pea genes to determine whether or not they function independently.  Yewah is pursuing graduate studies in ecology. USDA Forest Service.
  • Amanda Helin  (’98)- Scanning electron microscopy analysis of veg2-2 mutant of pea to determine if an inflorescence branch reverts to a vegetative branch.  Amanda is working as a research technician at the University of Chicago.
  • Gita Rao (’98)- Transformed pim mutant of pea with AP1 gene of Arabidopsis to determine whether or not there was functional homology between the two genes.  Gita graduated with a degree in English and is currently program director for Cabrini Connections in Chicago.
  • Kris Groff Barry (’98)=developed an in situ hybridization technique in pea so we could study the expression patterns of flowering genes in different pea mutants.  Kris received a Ph.D. in  horticulture at the University of Florida and is currently a postdoc at the University of Texas.
  • Laura Cox  (’98)- construction of plasmids with different markers for Agrobacterium transformation of plants.  Technical services at Epic Systems in Madison, WI.
  • Doreen Hartzell  (’98)- Morphological and genetic analysis of a non-flowering mutant of pea.  Doreen graduated with degrees in German and Biology, followed by a Fulbright Fellowship in Germany.
  • Lydia Ong (’96) - Role of Gibberellins in Floral Meristem Development in Pea.  University of Minnesota Medical School
  • Amanda Peterson Sarata (’96) - Amanda worked with Doug Wieczorek and used RFLP analysis to investigate possibility that the pea homolog of the Arabidopsis gene AP1 was the gene identified by the pim mutation in pea.  She worked as a laboratory technician in industry after graduation and is currently enrolled in a dual degree program in law (J.D.) and Science and Technology Policy (M.S.)
  • Sunshine Garber Beck (’96)- Investigated interactions among genes regulating the number of flowers formed per node on garden peas. Case Manager Assistant, Diocesan AIDS Ministry, Texas
  • Charles Johnston (’95) – Role of leaf primordial in early flowering in pea. Editor, Lost Planet
  • Glen Rundell (Rochester Institute of Technology)-Image analysis to quantify meristem size differences between det and wild-type peas. President and CEO, Advanced Information Management Group, Schenectady, NY
  • Mark Havrilla (Kenyon College)-Image analysis of meristem shape in pea mutants.
  • Amy Horan (University of Wisconsin, River Falls)-Premature senescence in det mutants of pea, administrative associate, St. Johns Luthern Church, Northfield, MN
  • Lisa Ainsworth (UCLA) and Kate Ainsworth Lovrien (’95)-Misconceptions in plant biology (funded by NSF REU site in Cognitive Studies). Kate went to graduate school at Washington University.
  • Doug Wieczorek (’95) - Used RFLP analysis to investigate possibility that the pea homolog of the Arabidopsis gene AP1 was the gene identified by the pim mutation in pea.  PhD, the University of Iowa.
  • Jenny Fick (’95)- Morphometric Analysis of a Meristem Identity Mutant of Pea. She presented her research at the Pew Biological Sciences Symposium and at the Carleton Student Research Symposium in the Fall of 1995.  Veterinarian, graduated from University of Michigan Veterinary School.
  • Renee Delozier  Read (’94)– Role of flowering time genes in pea on meristem development in culture. Ph.D. Washington University
  • Karen Ong (’94)-Effect of light and sucrose on timing of initiation of shoot meristems in culture. High school teacher, Brookline, MA.
  • Monique Oliver (’94) – Analysis of growth of rapid cycling Brassicas. News producer,  WTVD ABC11, Durham, NC
  • David Remucal (’93)– Heterostylous development in purple loosestrife. Graduate school, University of Colorado, Denver
  • Samara Reck-Peterson (’93)-Stability of determination for floral shoot organogenesis in tobacco internodes. Ph.D. Yale, postdocs at Standford and UCSF.
  • Eugene Hong (’93)-det-a heterochronic mutation affecting apical senescence in pea. M.D./Ph.D. University of Washington.
  • Pam Holloway (’92)-Flowering in culture apices of pea. Career in teaching and directing high school theater.
  • Andrea Winbauer (’92)-Effects of light and sucrose on stability of shoot organogenesis in tobacco internodes. Attended graduate school at Washington State University, Pullman. Technologist, ARUP Labs.
  • Chris Navia (’92)-Competence for floral determination in tobacco. Graduate study in political science, University of Michigan.
  • Yvonne Stephanie Carrasco (’92)-Effect of veg on inflorescence determination in pea. Research coordinator, University of Texas, El Paso.
  • Erik Stokstad (’92)-Isolating plasma membrane proteins from single shoot apices. Writer for Science
  • Tanya Halvorsen (’91, MIT)-Photoperiodic induction of gene expression in Nicotiana.  Ph.D. MIT
  • Pat Carriere (’91)-Effects of high levels of B-chromsoomes on embryo development in maize
  • Steve Halligan (’91)-Assay to isolate plasma membrane proteins form individual shoot apices.
  • Louise Latterell (’91)-Stability of determination for shoot organogenesis in tobacco. University of Minnesota Medical School, currently a family physician in Madison, WI.
  • Phillip Chung (’91) – Effect of genotype on timing of inflorescence determination in pea. Physician
  • Paula Hong (’91)-Shoot regeneration from cultured pea meristems. Pediatric opthalmogist, Reno, NV
  • Carolyn Ferguson (’90)-Inflorescence determination in pea. Ph.D. University of Texas, Austin, postdoc Washington University, currently a faculty member at Kansas State.
  • Tim Jegla (’90)-Stability of determination for vegetative shoot formation in cultured tobacco. Ph.D. in neurobiology from Washington University, postdoc at Stanford, currently work in biotech industry.
  • Tracy Smith (’90)-Gene expression in photoperiodically induced leaves of Pharbitis and Nicotiana. Ph.D. MIT, postdoc at UCSF, currently a science writer
  • Marti Louw (’90) - Competence for floral development. Associate producer, WGBH/NOVA, graduate studies in media at Carnegie Mellon.
  • Quynh Nguyen (’89) - Effect of the veg mutation on axillary bud development in pea. Went to the University of Minnesota Medial School.
  • Scott Moses (’89) - Transposon tagging of the Maryland mammoth gene in Nicotiana tabacum. University of Minnesota Medical School, currently a family physician in MN.
  • Daniel Christ (’89, St. Olaf) - Developmental physiology of the det mutant of Pisum sativum. Currently a horticulture assistant for a commercial greenhouse.
  • Heidi Asbjorensen (’89) - Readings in agroforestry. Graduate study at Yale in forestry.
  • Bev Nazarian (’89) - Leaf processes in flowering in tobacco. University of Minnesota Medical School. Currently a pediatrician in Worccester, MA
  • Sarah Huber (’88) – Floral development of asters. Peace Corps in Boliva, research technician at Cornell, currently  a high school teacher in Maryland.
  • Ann Holtz (’88) - Competence of tobacco internode tissue for floral development. Lab manager, Clonetech Technologies, CA.
  • Lynn Quam (’88, St. Olaf) – Effect of position of pea axillary bud development. Research technician at Mayo.
  • Lois Bauer (’87) – Effect of plant growth substances on Drosera rotundifolia. Went to Johns Hopkins Medical School, now a pediatrician.
  • Cole Hannon (’87) – Competence for floral development in tobacco seedlings. Clinical program manager, Medtronic.