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 strategies to understand and improve cereals and grasses
The Lemaux laboratory focuses on development and use of genetic and genomic technologies for monocotyledonous species, wheat (Triticum aestivum), sorghum (Sorghum bicolor), barley (Hordeum vulgare), and rice (Oryza sativa). Long-term objectives are to use these technologies to study gene function, explore basic biological questions and to improve crops.
Methods for stably transforming cereal crops are more routine today than decades ago, but challenges still exist. Nearly all methods utilize in vitro- 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 other varieties of interest. For this reason, our laboratory developed other culturing methods, including new target tissues, like cultured adventitious meristems and highly regenerable, green tissue (right), 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., 2001; Cho et al., 2000a; Cho et al., 2000b; Zhang et al., 1999, 2002b; Gurel et al., 2009). Presently we are implementing a “game-changing” technology, developed at Pioneer Hi-Bred. It involves introducing developmental genes, babyboom and wuschel, that reset cells to an early developmental stage, leading to transformation success with more cultivars and the use of explants, like seeds and leaves (Lowe et al. 2016. Plant Cell 28:1998–2015).
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 preferentially to genic regions (Koprek et al., 2001; Brown et al., 2014). Inverse PCR was used 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., 2014).
With effective transformation methods, transgenic cereals were created that over- and under-expressed elements of the NADPH thioredoxin (Trx) system (with B. Buchanan, UCB). To achieve maximal grain Trx overexpression, we used seed-specific promoters and vacuolar targeting to direct transgene expression to protein bodies of the endosperm (Cho et al., 1999b; Cho, M.-J., Lemaux P.G., Buchanan B.B. Production of proteins in plant seeds. Official Gazette of the United States Patent and Trademark Office Patents. Patent Number: US 07157629, January 2, 2007. The Regents of the University of California). 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) - important traits for malting.
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 approach for trx h9, demonstrated that this mitigated the devastation of preharvest sprouting. Using three years of data from field-grown plants, yield and dough quality of transgenic lines generally responded positively in both a low- and a high-gliadin variety.
Earlier evidence in barley showed that changes in the endosperm caused effects in the embryo and aleurone. Work in Arabidopsis showed that trxh9, unlike other thioredoxins, is located in the cell membrane and may function in cell-to-cell communication of the redox state (Meng et al. 2010) - possibly functioning in communication between endosperm, embryo and aleurone.
Recent work overexpressing Trx h5 in sorghum appears to lead to improved digestibility (Wong et al., unpublished), important becausesorghum flour is the least digestible of all cereals, particularly after cooking. Homozygous transgenic seed also appear to have increased seed size. To gene function studies in cereals, we developed 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 BER grant. The goal of this collaborative project, between UC Berkeley, UCANR, the Joint Genome Institute and the Pacific Northwest National Laboratory, is to use transcriptomics and epigenetics to develop an in-depth understanding of drought tolerance in Sorghum bicolor in the field. Recent studies have shown that environmental stresses – like drought – can lead to epigenetic changes, allowing plants to respond to changing environments more quickly. Specifically it is well known that associations of specific bacteria and fungi with plants have positive effects on plant fitness. EPICON researchers will also track changes in the sorghum-associated microbial communities to determine whether they correlate with changes that directly contribute to the crop's drought tolerance.
The duration and intensity of drought is increasing in California and worldwide largely due to climate change. Faculty member Peggy Lemaux is leading a $12.3 million Department of Energy Biological and Environmental Research-funded project to examine how the drought- tolerant cereal crop, sorghum, survives water limitation.
Lemaux and fellow PMB researchers John Taylor, Devin Coleman-Derr and John Vogel, are partnering with Elizabeth Purdom, Department of Statistics, Jeff Dahlberg and Robert Hutmacher, directors of ANR Research Stations, Axel Visel from DOE’s Joint Genome Institute and Christer Jansson, at DOE’s Pacific Northwest National Laboratory.
Five Year Project
This five-year project, “Epigenetic Control of Drought Response in Sorghum" (EPICON), comes in the midst of an historic drought in California. During three years of field-testing, researchers will investigate responses of sorghum to drought, including how gene expression changes at the transcriptional and epigenetic levels, which proteins and metabolites are altered and interactions with its microbiome.
"Historically, the genetic manipulation of crops, which is critical to increasing agricultural productivity, has concentrated on altering the plant’s genetic sequence, encoded in its DNA," said Lemaux.
"However, recent studies have shown that environmental stresses – in our case drought – can lead to epigenetic changes in a plant’s genetic information. Because epigenetic changes occur without altering the underlying DNA sequence, they allow plants to respond to a changing environment more quickly."
It is now well known that associations of specific bacteria and fungi with plants have positive effects on plant fitness. EPICON researchers will also track changes in the sorghum-associated microbial communities to determine whether they correlate with changes that directly contribute to the crop's drought tolerance.
EPICON researchers will develop better predictions about how sorghum and other cereal crops are affected by future climate scenarios, leading to approaches to improve crop growth and production under water-limiting conditions.
As a Cooperative Extension Specialist, I have 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, 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). With my long-time assistant, B. Alonso, we created games, displays, videos and middle-school afterschool curricula, DNA for Dinner, Backyard Mystery and Learning Plant Biology: It’s All in the Touch. A recent project, CLEAR (Communication, Literacy, Education for Agricultural Research) was initiated with funds from UCOP’s Global Food Initiative. CLEAR aims to enable undergrads, grads and postdocs with skills in communicating about science with the media, legislators and the public. CLEAR fellows write pieces for the popular press, organize roundtables, participate in outreach events and develop videos.
Xu, L., Naylor, D., Dong, Z., Simmons, T., Pierroz, G., Hixson, K., Kim, Y-M., Zink, E.M., Engbrecht, K.M., Wang, Y., Gao, C., DeGraff, S., Madera, M., Sievert, J.A., Hollingsworth, J., Birdseye, D., Scheller, H.V, Hutmacher, R.B., Dahlberg, J., Jansson, C., Taylor, J., Lemaux, P.G., Coleman-Derr, D. 2018. Drought delays development of the sorghum root microbiome and enriches for monoderm bacteria. Proceedings of the National Academy of Sciences USA 115 (8) doi: 10.1073/pnas.1717308115.
Kirst, H., Gabilly, S.T., Niyogi, K.K., Lemaux, P.G., Melis, A. 2017. Increasing crop plant canopy productivity upon decreasing the light-harvesting antenna size of photosynthesis. Planta 245:1009-1020; DOI : 10.1007/s00425-017-2659-y.
Kleist, T.J., Cartwright, H.N., Perera, A.M., Christianson, M.L., Lemaux, P.G., Luan, S. 2017. Genetically Encoded Calcium Indicators for Fluorescence Imaging in the Moss Physcomitrella: GCaMP3 Provides a Bright New Look.. Plant Biotechnology Journal July 20, 2017 doi: 10.1111/pbi.12769.
Singh, S., Tripathi, R.K., Lemax, P.G., Buchanan, B.B., Singh J. 2017. Redox-dependent interaction between thaumatin-like protein and β-glucan that influences the malting quality of barley. Proceedings National Academy of Science 114 (29) 7725-7730.
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) http://www.globalsciencebooks.info/JournalsSup/12EJPSB_6_SI1.html
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
Award of Excellence, Extension Education Community Education Materials, ASA-CSSA-SSA, November 2015
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