Peggy G. Lemaux
- Peggy G. Lemaux
- Crop Biotechnology
- Cooperative Extension Specialist
- 411B Koshland Hall
- Berkeley, California 94720
- Phone 510.642.1589
- Lab Phone 510.642.1589
- Fax 510.642.4995
Outreach web site: ucbiotech.org
Ph.D. University of Michigan, 1977
B.S. Miami University, 1968
Cooperative Extension Specialist Peggy Lemaux’s laboratory performs both basic and applied research focused primarily on cereal crops, like sorghum, wheat, rice and barley. The objectives of these studies are to better understand crop plants and to use that knowledge to improve their performance and quality. More recently efforts with colleagues have focused on bioenergy – especially in the versatile feedstock, sorghum. In addition to research, Lemaux develops educational resources on food and agriculture that are disseminated to professionals, the media and consumers. These resources include an award-winning website (http://ucbiotech.org) that has afterschool curricula for middle school students, educational displays and games, videos, PowerPoint presentations and fact sheets. In 2015 the Global Food Initiative, through the UC Office of the President, provided resources for the CLEAR (Communication, Literacy and Education for Agricultural Research) program. This effort focuses on mentoring undergrads, grads and postdocs to engage in science-based communication with the media, legislators and the general public.
Use of genetic engineering strategies to understand and improve cereals and grasses
The Lemaux laboratory’s focus is on the development and use of genetic engineering and genomic strategies for monocotyledonous species, such as the cereals, wheat (Triticum aestivum), sorghum (Sorghum bicolor), barley (Hordeum vulgare), rice (Oryza sativa) and several grass species. Our long-term objectives are to use engineering and genome-editing technologies to study gene function, to explore basic biological questions and to use this information to improve crops.
Methods for stably transforming cereal crops are more routine today than two decades ago, but challenges still exist. Nearly all methods utilize in vitro-derived tissue culture materials, which leads directly or indirectly to limitations in varieties that can be transformed, to somaclonal variation and to transgene expression instability.
Most cereal transformation efforts involve culturing immature embryos to generate embryogenic or organogenic tissue. This approach has been successful for model genotypes but has been challenging for commercially important varieties. For this reason, our laboratory developed other culturing methods, including new target tissues, like cultured adventitious meristems (left) and highly regenerable
, green tissue (right, below), a developmental stage between embryogenic and organogenic tissue. Using these methods, we developed efficient transformation systems for previously recalcitrant varieties of wheat, barley, corn, rice, oat, sorghum and forage and turf grasses (e.g., Cho et al., 1998, 1999a; Ha et al., 2000; Cho et al., 2000a; Cho et al., 2000b; Zhang et al., 1999, 2002b; Gurel et al., 2009).
Another focus of the lab relates to functional genomics. For these efforts in barley, we used the maize transposable element, Ds, and its transposase gene (with P. Bregitzer, USDA-ARS). When these two elements are present in the same cell, Ds is activated and transposes to new genomic locations, preferentially into genic regions (Koprek et al., 2001; Brown et al., 2014a). The inverted repeat regions of the Ds sequence are then used for inverse PCR to sequence flanking DNA, identify the gene into which Ds inserted and to map its location (Cooper et al., 2004; Singh et al., 2006). Efforts have continued to identify tagged genes in barley (Brown et al., 2014b).
With the availability of effective transformation methods, transgenic cereals were created that over- and under-express elements of the NADPH thioredoxin (Trx) system (with B. Buchanan, UCB). To achieve maximal Trx overexpression in the grain, we used seed-specific promoters and vacuolar targeting to direct the transgenes to protein bodies of the endosperm (Cho et al., 1999b; Cho et al., 2007). Homozygous Trx h5 transgenic barley seeds germinated faster, alpha-amylase levels rose earlier and levels of the starch-degrading enzyme, pullulanase, were higher (Cho et al., 1999) - useful traits for the malting industry.
In wheat, homozygous lines overexpressing Trx h5 had lowered allergenicity in the gliadin fraction, as assessed using a canine model (Li et al., 2009), and improved dough quality with poor quality wheat flour (unpublished). Building on this work, Chinese collaborators, using an antisense construct for trx h9, demonstrated that this mitigated the devastating problem of preharvest sprouting. Using three years of data from field-grown plants, yield and quality of transgeniclines generally responded positively in both a low- and a high-gliadin variety.
As earlier evidence in barley had shown, changes in the endosperm caused effects in the embryo and aleurone. Work in Arabidopsis showed that thioredoxin, trxh9, unlike other thioredoxins, is located in the cell membrane and may function in cell-to-cell communication of the redox state (image right, Meng et al. 2010) - possibly related to communication between the endosperm and the embryo and aleurone. Future work will use proteomics and transcriptomics to continue unraveling the redox communication network.
Recent work overexpressing Trx h5 in sorghum appears to lead to improved digestibility (Wong et al., unpublished), important because sorghum flour is the least digestible of all cereals, particularly after cooking. Homozygous transgenic seed also appear to have increased seed size. To accelerate gene function studies in cereals, we are developing transformation strategies for green foxtail (Setaria viridis), a fast-cycling, diploid C4 monocot.
In 2015 the lab started the EPICON project, funded by a 5-year DOE grant. This is a collaborative project between UC Berkeley, UCANR, Joint Genome Institute and the Pacific Northwest National Laboratory. The goal of the EPICON project is to use transcriptomics and epigenetics to develop an in-depth understanding of drought tolerance in Sorghum bicolor in the field. We will utilize pre-flowering and post-flowering drought tolerant lines in a three-year trial to identify key mediators of drought tolerance. We will also observe fluctuations in the microbial populations over time, which might also function in sorghum’s ability to survive drought.
My faculty position, as a Cooperative Extension Specialist, mandates statewide responsibility for outreach and educational programming related to agriculture and food. These efforts are designed to increase public understanding of agricultural practices, food production and the impact of new technologies, including biotechnology and genome editing, on food and agriculture. Educational programming and resources that are developed include development of an award winning, informational website, http://ucbiotech.org, which provides science-based information and resources. Two articles related to these efforts were published in Annual Review of Plant Biology, “Genetically Engineered Crops and Foods: A Scientist's Analysis of the Issues. Part I and II (Lemaux PG. 2008; 2009). Along with my long-time assistant, B. Alonso, we have created games, displays, videos and afterschool curricula. The curricula, aimed at middle school students, are DNA for Dinner, Backyard Mystery and Learning Plant Biology: It’s All in the Touch. A recent effort, CLEAR (Communication, Literacy, Education for Agricultural Research) was initiated with funds from UCOP’s Global Food Initiative. This program aims to enable undergrads, grads and postdocs to gain skills in communicating with the media, legislators and the public about issues related to science. CLEAR fellows engage in writing pieces for the popular press, organizing roundtables, participating in outreach events and developing videos. A graduate class was offered to further students’ skills in interacting with the public, Science Communication: Nuisance or Necessity?
Muñoz-Amatriaín, M., Lonardi, S., Luo, MC., Madishetty, K., Svensson, J.T., Moscou, M.J., Wanamaker, S., Jiang, T., Kleinhofs, A., Muehlbauer, G.J., Wise, R.P., Stein, N., Ma, Y., Rodriguez, E., Kudrna, D., Bhat, P.R., Chao, S., Condamine, P., Heinen, S., Resnik, J., Wing, R., Witt, H., Alpert, M., Beccuti, M., Bozdag, S., Cordero, F., Mirebrahim, H., Ounit, R.,Wu, Y., You, F., Zheng, J., Šimková, H., Doležel, J., Grimwood, J., Schmutz, J., Duma, D., Altschmied L., Blake, T., Bregitzer, P., Cooper, L., Dilbirligi, M., Falk, A., Feiz, L., Graner, A., Gustafson, P., Hayes, P.M., Lemaux, P.G., Mammadov, J. and Close, T.J. 2015. Sequencing of 15,622 gene-bearing BACs clarifies the gene-dense regions of the barley genome. The Plant Journal 84: 216-227.
Brown, R.H., Singh, J., Singh, S., Dahleen, L.S., Lemaux, P.G., Stein, N., Mascher, M. and Bregitzer, P. 2014a. Behavior of a modified Dissociation element in barley: A novel tool for genetic studies and for breeding transgenic barley. Molecular Breeding 35 (3): 85 DOI 10.1007/s11032-015-0193-9.
Brown, R.H., Dahleen, L.S., Lemaux, P.G., and Bregitzer, P. 2014b. Registration of the Barley Transposon-Tagged Population I: Seventy Lines - Each with a Single, Unique Site of Ds Insertion. J Plant Registrations 8: 226-230.
Coulman, B., Dalai, A., Heaton, E., Lee, P. C., Lefsrud, M., Levin, D., Lemaux, P.G., Neale, D., Shoemaker, S.P., Singh, J., Smith, D.L. and Whalen J.K. 2013. Developments in crops and management systems to improve lignocellulosic feedstock production. Biofuels Bioproducts and Biorefining 7: 582–601.
Ren, J.-P., Li, Y., Wong, J.H., Meng L., Cho, M-J., Buchanan B.B., Yin, J. and Lemaux P.G. 2012. Modifying Thioredoxin Expression in Cereals Leads to Improved Pre-Harvest Sprouting Resistance and Changes in Other Grain Properties. Seed Science Research 22: S30-S35.
Wong, J.H., Pedersen, J.F., Buchanan, B.B. and Lemaux, P.G. 2012. Western Blot Analysis Uncovers Clues to Prolamin Digestibility in Raw and Cooked of Meal from Sorghum and Corn. European Journal of Plant Science and Biotechnology 6 (Special Issue 1): 56-65 (Print ISSN 1752-3842)
Gurel S., Gurel E., Miller T.I. and Lemaux P.G. 2012. Agrobacterium-Mediated Transformation of Sorghum bicolor Using Immature Embryos. In: Transgenic Plants: Methods and Protocols. Methods in Molecular Biology. Dunwell J.J., Wetten A.C. 847: 109-122.
Meng, L., Wong, J.H., Feldman, L.J., Lemaux, P.G. and Buchanan, B.B. 2010. A membrane-associated thioredoxin required for plant growth moves from cell to cell, suggestive of a role in intercellular communication. Proceedings of the National Academy of Sciences USA 107: 3900-5.
Meng, L., Zhang, S. and Lemaux, P.G. 2010. Developing a Molecular Understanding of In Vitro and In Planta Shoot Organogenesis. In: Plant Tissue Culture, Development and Biotechnology. Trigiano, R. N. and Gray, D. (eds.), CRC Press, pp. 259-278.
Li, Y., Ren, J., Cho, M-J., Zhou, S., Kim, Y.B., Guo, H., Wong, J.H., Niu, H., Kim, H-K., Morigasaki, S., Lemaux, P.G., Frick, O.L., Yin, J., Buchanan, B.B. 2009. The Level of Expression of Thioredoxin is Linked to Fundamental Properties and Applications of Wheat Seeds. Molecular Plant 2: 430-441.
Gurel, S., Gurel, E., Kaur, R., Wong, J., Meng, L., Tan, H-Q., Lemaux, P.G. 2008. Efficient, Reproducible Agrobacterium-mediated Transformation of Sorghum Using Heat Treatment of Immature Embryos. Plant Cell Reports (DOI 10.1007/s0029-008-0655-1).
Wong J.H., Lau T., Cai N., Singh J., Pedersen J.F., Vensel, W.H., Hurkman, W.J., Wilson, J.D., Lemaux, P.G., Buchanan, B.B. 2008. Digestibility of Protein and Starch from Sorghum (Sorghum bicolor) Is Linked to Biochemical and Structural Features of Grain Endosperm. Journal of Cereal Science 49: 73-82.
Zhang, S., Gu, Y.Q., Singh, J., Coleman-Derr, D., Brar, D.S., Lemaux, P.G. 2007. New insights into Oryza genome evolution: High gene colinearity and differential retrotransposon amplification. Plant Molecular Biology 64: 589-600.
Singh, J., Zhang, S., Chen, C., Cooper, L., Bregitzer, P., Sturbaum, A., Hayes, P. and Lemaux, P.G. 2006. High-frequency Ds remobilization over multiple generations in barley facilitates gene tagging in large genome cereals. Plant Molecular Biology 62: 937–950.
Lemaux, P.G. 2012. Genetically Engineered Crops Can Be Part of a Sustainable Food Supply: Food and Food Safety Issues. In: The Role of Biotechnology in a Sustainable Food Supply (Popp, J., M. Jahn, M. Matlock and N. Kemper, eds.), Cambridge, Chapter. 7, pp. 122-140.
Lemaux, P.G. 2010. What's Slowing Commercialisation of GE Crops? Regulatory, Economic, Intellectual Property and Consumer Acceptance Issues. In '1st Australian Summer Grains Conference'. Gold Coast, Australia. (Eds B George-Jaeggli, DJ Jordan). (Grains Research and Development Corporation).
Lemaux P.G. 2007. “Do We Need Genetically Modified Foods to Feed the World? A Scientific Perspective”. In: Realities of Nutrition, 3rd Edition. Morrill JS and Deutsch RM. Orange Grove Publishing, Menlo Park CA, pp. 268-270.
Honors and Awards
American Society of Plant Biologists Excellence in Education Award, 2012
President, American Society of Plant Biologists, 2011
Society for In Vitro Biology 2010 Lifetime Achievement Award - Society for In Vitro Biology - 2010
Fellow - Crop Science Society of America - 2007
Distinguished Service Award, Outstanding Outreach - Cooperative Extension Academic Assembly Council, Division of Agriculture and Natural Resources - 2006
Dennis R. Hoagland Award for outstanding contribution to agricultural research - American Society of Plant Biologists - 2003
Fellow - American Association for the Advancement of Science - 2002
Distinguished Service Award, Outstanding Research - Cooperative Extension Academic Assembly Council, Division of Agriculture and Natural Resources - 1997
Honored Women of the University of California, Berkeley - UC Berkeley - 1995