Robert Carver, Cohn, Marc A.
INVESTIGATOR: Cohn, M. A.
PLANT PATHOLOGY & CROP PHYSIOL
LOUISIANA STATE UNIVERSITY
BATON ROUGE, LOUISIANA 70893
ENVIRONMENTAL AND GENETIC DETERMINANTS OF SEED QUALITY AND PERFORMANCE
CLASSIFICATION HEADINGS: R136 . Conservation of Biological Diversity; S5240 . Seeds and other plant propagules; F1020 . Physiology; R203 . Plant Biological Efficiency and Abiotic Stresses Affecting Plants; S0330 . Wetland and riparian systems; S2150 . Aquatic plants; R206 . Basic Plant Biology
NON-TECHNICAL SUMMARY: Spartina alterniflora is the main plant that prevents erosion of coastal and salt-marsh soils along the Gulf Coast of the United States and elsewhere. While the plant can reproduce vegetatively, use of transplants to stabilize at-risk coastal areas is prohibitively expensive to impossible on a large scale. Therefore, planting from seeds is most desirable. However, the seeds are unusual because they die when they are dried (recalcitrant); in contrast, most crop seeds can be stored dry (orthodox) for long periods of time under the proper conditions. Use of Spartina seeds to control coastal erosion would be a viable restoration strategy if the seed handling, processing and plant varietal conservation could be improved. The goal of the project is to identify the causes of recalcitrant seed death and define methods to conserve these seeds in a dry state. In previous research with other plants, three possible reasons for recalcitrant seed death have been proposed: oxidative stress, lack of stress protective proteins, and lack of protective sugars. However, it is not clear whether previous correlations are the result of interactions with seed aging, germination processes, or dormancy. Using a novel comparative approach, with orthodox Spartina pectinata and Spartina spartinae as physiological controls, our previous work has ruled out common forms of oxidative stress as the cause of recalcitrant-seed death. In the work encompassed by this proposal, this approach will be extended to protective proteins and sugars. Should we identify specific proteins and sugars that are associated with seed desiccation tolerance, biotechnology strategies can be used to introduce these features into Spartina alterniflora seeds. Because many economically important plants have recalcitrant seeds (e.g. coffee, tea and avocado), the impact of our findings will be relevant for seed conservation and production of crop plants.
OBJECTIVES: Goals/Objectives. 1. Identify and characterize biophysical, genetic, and environmental factors regulating or influencing seed development, germination, vigor and dormancy. 2. Determine and model the biotic and abiotic factors affecting seed germination, seedling emergence, and establishment of sustainable populations in natural and agro-ecological systems. 3. Develop, evaluate, and transfer technologies to assess and improve seed and seedling quality, health, performance, utilization, and preservation.Expected Outputs. 1. Effects of environmental stress during seed development on seed quality. 2. Influence of seed desiccation rate and time of maturity on seed quality. 3. Identification and characterization of genes and biochemical processes important in the development and expression of seed quality. 4. Development of post-harvest methods to enhance seed quality.
APPROACH: Using the comparative physiology of Spartina alterniflora (recalcitrant) vs. S. pectinata (orthodox)in response to seed desiccation, the roles of DNA oxidation, protein oxidation, RNA oxidation, protective proteins, protective sugars, and antioxidants will be studied to identify the cause of recalcitrant seed death. Standard biochemical, electrophoretic and proteomics methods will be utilized. Seeds of each species will be flash-dried to specific seed moisture contents and parameters quantified. Both dormant and non-dormant seeds will be assayed. This evaluation approach avoids confusion of artifacts due to seed aging, germination, and dormancy with biochemical lesions responsible for inability of Spartina alterniflora seeds to survive desiccation. Efforts will comprise publication in peer reviewed journals, presentations at regional, national and international meetings, and extension/producer groups, as appropriate.
KEYWORDS: spartina alterniflora; seed death; seed recalcitrance; coastal erosion; soil stabilization; desiccation tolerance; seed physiology; proteomics; oxidative stress; nonreducing sugars
PROGRESS: 2010/01 TO 2010/12
OUTPUTS: The results obtained have been incorporated into lecture materials for undergraduate and graduate level courses, presented each year. The project has also supported the research training of one doctoral student (seed physiology, biochemical techniques, and mass spectroscopy) and one undergraduate (seed physiology and scientific method). Services included advising faculty and students in the LSU AgCenter Coastal Plants Project concerning development of seed germination protocols for various marsh plant species. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: There are three target audiences for these efforts: (1)the seed conservation community, (2) the coastal preservation community, and (3) undergraduates and graduate students in seed physiology and professional development courses. The investigator has participated in and advised groups and individuals on the relevant aspects of recalcitrant seed biology and experimental strategies/design. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
IMPACT: 2010/01 TO 2010/12
Over 100 differentially expressed proteins among Spartina alterniflora (desiccation intolerant, DI), Spartina pectinata (desiccation tolerant, DT) and Spartina spartinae (desiccation tolerant) seeds were found by two-dimensional gel electrophoresis between DT vs. DI species, and some of these differences included differential post-translational protein phosphorylation and protein glycosylation. Some of these protein profile differences were detected after fractionation of total soluble protein extracts, while others were detected in a heat-stable protein fraction. Spartina alterniflora seed protein profiles also changed as a result of storage of the seeds in cold water, which we have shown triggers the transition from the dormant to the germinable, non-dormant state. The identification of these proteins via mass spectroscopy should provide clues as to the nature of desiccation intolerance and dormancy of Spartina alterniflora seeds.
PUBLICATIONS (not previously reported): 2010/01 TO 2010/12
Subudhi, P.K., A. Parco, P. Singh, T. DeLeon, and M. A. Cohn (2010) Quantitative trait loci for seed shattering and seed dormancy in weedy red rice. CSSA Abstracts. 2010 Annual Meeting. Long Beach, CA. http://a-c-s.confex.com/crops/2010am/webprogram/Paper61295.html
PROGRESS: 2009/01/01 TO 2009/12/31
OUTPUTS: We developed (1) a new technique to extract and fractionate proteins from recalcitrant and orthodox Spartina seeds, and (2) a new process to determine if recalcitrant seed death is caused by physical or biochemical factors. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: There are two target audiences for these efforts: (1) the seed conservation community, and (2)the coastal preservation community. The investigator has participated in and advised groups and individuals (both within the research community and outside of it) on relevant aspects of recalcitrant seed biology. The investigator has participated in scientific meetings and field day presentations in the area of expertise. PROJECT MODIFICATIONS: Not relevant to this project.
IMPACT: 2009/01/01 TO 2009/12/31
(1) We found the optimal extraction buffer components, processing temperatures and durations, and centrifugation programs to reproducibly obtain total and heat-stable protein fractions from Spartina alterniflora, Spartina pectinata, and Spartina spartinae seeds for one-dimensional and two-dimensional gel electrophoretic analysis. This will allow meaningful comparisons of proteomic profiles and likely identification of key proteins involved in both recalcitrant seed death and loss of Spartina seed dormancy. (2) Different drying temperatures changed only the rate of water loss. Therefore, recalcitrant seed death is caused by a physical process (deficiency), rather than biochemical events. The impact of these results is to justify the focus of subsequent research upon identification of structural proteins required for survival of seeds in the dry state.
PUBLICATIONS: 2009/01/01 TO 2009/12/31
Subudhi, P.K., A. Parco, P. Singh, T. DeLeon, N. Baisakh, and M. A. Cohn (2009) Development of an introgression library of red rice for mapping and cloning of genes for weedy traits. Plant & Animal Genomes XVII Conference, January 10-14, 2009. San Diego, CA
Name: Cohn, M. A.