Ann Hirsch
email: ahirsch@ucla.edu
phone: (310) 206-8673
fax: (310) 206-5413
office: 316 Botany
lab: 301
homepage: http://www.mcdb.ucla.edu/Faculty/Hirsch
Research Interests
We study the interaction between nitrogen-fixing bacteria (alpha-rhizobia) and legumes such as alfalfa, pea, and soybean in order to determine why this interaction occurs exclusively with certain plants. The roots of these plants house the bacteria, often in root nodules, where the bacteria convert atmospheric nitrogen into ammonia, thereby allowing the plant to live without added nitrogen fertilizer. We also investigate "non-traditional" nitrogen fixers, such as beta-rhizobia and actinomycetes, and the plants associated with them. Because these bacteria exhibit metabolic activities, such as cellulose degradation, as well as nitrogen fixation, they have potential not only to be used for enhancing crop nitrogen nutrition, especially as increased energy costs result in greater fertilizer expenditures, but also in the production of biofuels. To this end, we have undertaken a sequencing project of four Burkholderia genomes and two Micromonospora (actinobacteria) genomes. We are also interested in bacterial biofilm formation, especially by plant-associated bacteria. Such bacteria enhance plant growth by the secretion of specific chemicals and also by competing with root pathogens. Lastly, we have developed DNA-based methods to verify the authenticity of and to detect the presence of contaminants and adulterants of herbal medicines and botanicals. Botanicals are not regulated by the FDA, and hence are likely to be contaminated or adulterated. One of the most abused is Hoodia gordonia, which is used as a weight loss aid.
Selected Publications
Fujishige, N.A., Jankaew, K., and Hirsch, A.M.. 2009. Biofilm formation in Sinorhizobium meliloti Biology of Plant-Microbe Interactions 6: - [link].
Hirsch, A.M., Lum, M.R. and Fujishige, N.A.. 2009. Microbial encounters of a symbiotic kind—attaching to roots and other surfaces Root Hairs. Plant Cell Monographs 12: - [link].
De Hoff, P.L., Brill, L.M. and Hirsch, A.M.. 2009. Plant lectins: the ties that bind in root symbiosis and plant defense Mol. Gen. Genom 282: 1-15 .
Hirsch, A.M.. 2009. Bernard O. (Bernie) Phinney Plant Sci. Bull 55: 57-59 .
Hirsch, A.M.. 2009. Bernard O. Phinney ASPB News 36: 26-27 .
Tominaga, A., Nagata, M., Futsuki, K., Abe, H., Uchiumi, T., Abe, M., Kucho, K., Hashiguchi, M., Akashi, R., Hirsch, A.M., Arima, S., and Suzuki, A.. 2009. Enhanced nodulation and nitrogen fixation in the ABA low-sensitive mutant enf1 (enhanced nitrogen fixation) of Lotus japonicus Plant Physiol : - [link].
Suzuki, A., Hara, H., Kinoue, T., Abe, M., Uchiumi, T., Kucho, K., Higashi, S., Hirsch, A.M., and Arima, S.. 2008. Split-root study of autoregulation of nodulation in the model legume Lotus japonicus J. Plant Res 121: 245-249 .
Nishiguchi, M.K., Hirsch, A.M., DeVinney, R., Vedantam, G., Riley, M.A., and Manksy, L.M. “Mini-review:. 2008. Deciphering evolutionary mechanisms between mutualistic and pathogenic symbiosis Vie et Milieu (Life and Environment) 58: 87-106 .
Lum, M.R. and Hirsch, A.M.. 2007. Molecular methods for the authentication of botanicals and detection of potential contaminants and adulterants IVth International Conference on Quality and Safety Issues Related to Botanicals 720: 59-71 .
Lum, M.R., Lee, A., and Hirsch, A.M.. 2007. ENOD40 gene expression and cytokinin responses in the non-nodulating non-mycorrhizal (Nod-Myc-) mutant, Masym3, of Melilotus alba Desr Plant Signal. Behavior 2: 33-42 .