Location: Plant Physiology and Genetics Research
2009 Annual Report
Objective 2: Determine the physiological, biochemical, and molecular factors limiting the growth and yield of oilseed, latex, and biomass crops that could be targeted for improvement in a conventiional and/or molecular breeding program.
Objective 3: Develop economical production systems for new/alternative industrial crops.
Guayule: Transgenic guayule lines with Mendel Technology were evaluated in the field for morphological traits and in the laboratory for rubber and resin contents. Preliminary analyses of the results do not indicate any significant increases in rubber, resin or biomass yield compared to the non-transgenetic parent. Samples from herbicide tests completed in 2008 are being evaluated for rubber and resin contents to determine if herbicides used in plant establishment affected rubber and resin yields. A three year field study was completed at Halfway, Texas to screen for cold tolerance in guayule germplasm. Samples were taken for biomass yield and rubber and resin concentration determination. A new test was established based on preliminary analyses of these results which showed there are differences in the germplasm for cold tolerance in guayule germplasm at this location. The first year of a study to determine the effects of month of harvest on guayule rubber, resin, and biomass yields and the subsequent regrowth of plants following harvest was conducted. A study was initiated to determine if a ploidy analyzer could be used to accurately reflect ploidy levels in guayule germplasm. Methods were developed for accelerated solvent extraction of resin and rubber from guayule tissue. These methods, coupled with the development of more rapid and accurate procedures for measuring resin and rubber, increased the speed of germplasm evaluation in field and growth chamber studies of guayule.
Other oilseeds: Selection nurseries were established for camelina and vernonia and improved germplasm identified for further evaluation and crossing.
1)an unpleasant odor,.
2)negative effects on soil properties,.
3)loss of latex in the waste liquid, and.
4)treatment and disposal costs. Results of research conducted by ARS scientists in Maricopa, AZ, showed that the unpleasant odor of the waste streams can be corrected, negative effects on soil properties can be overcome by recycling two of the waste streams and minimal treatment of the third waste stream, and lost latex can be recovered by recycling two of the waste streams. The results from this initial study indicate that the potential problems associated with the waste streams generated during guayule latex production can be overcome relatively easy and result in potential beneficial use of the waste streams, resulting in reduced treatment and disposal costs. 5. Effects of plant population and planting date effects on guayule latex, rubber, and resin yields. Guayule is being commercialized in the southwestern USA utilizing new germplasm lines that have not been fully evaluated for the effects of various agronomic practices on their biomass, latex, rubber, and resin yields. ARS scientists in Maricopa, AZ, evaluated three of the lines being used in commercialization for biomass, latex, rubber, and resin concentrations and yields at two plant populations (recommended and 2X recommended), two transplant dates (fall and spring), and six harvest dates (1 year old – 3.5 years old). Results showed little effect of transplanting date or plant population, but that spring harvests were better than fall harvests and the lines AZ-1 and AZ-3 had greater biomass, while AZ-5 had a higher content of latex, rubber, and resin . These results will be of benefit to the new guayule industry to determine optimum transplanting and harvesting dates, plant populations, and lines to use in guayule production. 6. Post-harvest storage effects on guayule latex, rubber, and resin contents and yields. Guayule is a new crop being commercialized for hypoallergenic latex production. Since natural processes that occur in the plant following harvest result in loss of latex almost immediately and immediate processing of shrub for latex on a commercial scale is not feasible, a storage system that maintains latex concentration and yield is needed. ARS scientists in Maricopa, AZ, compared nine different storage systems to fresh harvested shrub. Results showed that keeping harvested shrub moist prior to latex extraction maintained latex yields and concentration compared to dry storage, increasing extractable latex yields by as much as 100%. The recommendations developed from this research on postharvest storage of guayule will allow growers and processors more flexibility in their harvesting and processing schedules.
Coffelt, T.A., Williams, C.F. 2009. Characterization and recycling of waste water from guayule latex extraction. Industrial Crops and Products (29), pp. 648-653.
O'Quin, J.B., Mullen, R.T., Dyer, J.M. 2009. Addition of an N-terminal epitope tag significantly increases the activity of plant fatty acid desaturases expressed in yeast cells. Applied Microbiology and Biotechnology. 83:117-125.
Lessire, R., Cahoon, E., Chapman, K., Dyer, J.M., Eastmond, P., Heinz, E. 2009. Highlights of Recent Progress in Plant Lipid Research. Plant Physiology and Biochemistry. 47:443-447.
Salvucci, M.E., Coffelt, T.A., Cornish, K. 2009. Improved methods for extraction and quantification of resin and rubber from guayule. Industrial Crops and Products 2009. 30:9-16.
Chow, P., Nakayama, F.S., Blahnik, B., Youngquist, J., Coffelt, T.A. 2008. Chemical constituents and physical properties of guayule wood and bark. Industrial Crops and Products, 28:303-308.