2013 Annual Report
1a.Objectives (from AD-416):
Objective 1: Improve crop stress tolerance by determining, and developing technology to ameliorate, metabolic limitations by biological processes most sensitive to abiotic stress factors common in arid southwestern U.S. cropping systems. [NP 301, C4, PS 4A]
Sub-objective 1a: Improve crop tolerance to heat stress by devising approaches to improve the ability of Rubisco activase to activate Rubisco at leaf temperatures above the optimum for photosynthesis.
Sub-objective 1b: Develop new approaches to improve chilling tolerance by identifying metabolic mechanisms that limit biochemical/physiological processes most sensitive to chilling temperatures.
Objective 2: Develop improved germplasm resources for abiotic stress resistance and fiber quality in Gossypium barbadense and G. hirsutum utilizing and integrating classical and biotechnology-based methodologies. [NP 301, C3, PS 3C]
Sub-objective 2a: Develop improved germplasm resources for abiotic stress resistance and fiber quality in G. hirsutum utilizing and integrating classical and biotechnology-based methodologies.
Sub-objective 2b: Develop improved germplasm resources for abiotic stress resistance and fiber quality in G. barbadense utilizing and integrating classical and biotechnology-based methodologies.
1b.Approach (from AD-416):
The genetic potential of cotton, and crop species in general, for producing of abundant high quality economic yield is severely compromised by specific abiotic stresses, like temperature and water, that are endemic to the arid-southwestern U.S. In addition, early season chilling stress impacts yield by stunting growth and delaying planting date. The negative impact of these stresses is likely to intensify as the global climate changes and water availability becomes more limiting. The mission of this research unit is to use a multidisciplinary approach to improve stress tolerance and yield in cotton. Fundamental approaches that integrate physiology, biochemistry, biotechnology and classical plant breeding will be used to identify and modify the response of cotton to environmental stress. Through this research, new sources of cotton germplasm will be developed with improved stress tolerance, as well as higher fiber quality and enhanced yield. The basic biochemical strategies developed for improving stress tolerance in cotton will have broad application to the variety of crop plants cultivated in arid environments. BSL-1, App #P-3-98-1 3/4/98; Recert. 2/1/05. Replaces 5344-21000-008-00D (3/06) and 5347-21000-009-00D (3/10).
This is the final report for this project, which was terminated in March, 2013, and replaced with project 5347-21000-012-00D, Molecular Genetic Analysis of Abiotic Stress Tolerance and Oil Production Pathways in Cotton, Bioenergy and Other Industrial Crops". See the FY2013 Annual Report of the new project for additional information. Progress was made on all objectives and sub-objectives, all of which are under the ARS Plant Genetic Resources, Genomics and Genetic Improvement NP 301 Action Plan. Our first objective focused on improving stress tolerance in crops by determining and developing technology to ameliorate abiotic stress factors that are common in the arid southwestern U.S. In collaboration with scientists at the University of Arizona, ARS scientists in Maricopa, Arizona,developed and utilized high-throughput phenotyping methods to characterize the response of field-grown pima cotton varieties to heat and drought stress, and also determined the underlying metabolic responses associated with stress. This study, and the associated technologies developed for field-based phenotyping, have garnered considerable attention from the scientific community and serve as a model for further development of high-throughput, field-based phenotyping capabilities. Other research on the molecular mechanisms of heat stress response in plants revealed the importance of a protein called CP12 in regulating photosynthesis, and in a separate study, the crystal structure of a heat-sensitive protein called Rubisco activase was determined. In addition to heat stress, a portion of our work also focused on the molecular mechanisms of cold temperature adaptation in plants, because cold temperature can cause significant damage to cotton seedlings. In collaboration with scientists at the University of Guelph and the University of North Texas, scientists at the ARS determined the molecular signals and specific proteins that are involved in the cold-temperature regulation of omega-3 fatty acid desaturases in plants. These enzymes are known to play a critical role in cold temperature adaptation in plants, and these results underpin our current efforts to characterize the omega-3 desaturase gene family in cotton. The second main objective of our research project focused on developing improved germplasm resources for abiotic stress resistance and fiber quality breeding in Gossypium hirsutum. In collaboration with scientists at Monsanto Company and New Mexico State University, ARS scientists in New Orleans, Louisiana, College Station, Texas, and Maricopa, Arizona, developed an interspecific cotton recombinant inbred mapping population that was registered with the National Plant Germplasm System. Seed packets for the population were deposited at two ARS germplasm centers, and the associated phenotypic and genotypic information was submitted to the public cotton genomics database, CottonGen. Registering this mapping population has increased its accessibility to the global cotton community, and will undoubtedly facilitate the genetic improvement of fiber quality in Upland cotton.
Identification of the omega-3 fatty acid desaturase gene family in cotton. The production of cotton in arid regions would benefit from development of cold-tolerant cotton seedlings, which would allow for earlier planting dates and harvesting before the hottest, driest parts of the growing season. ARS scientists at the US Arid Land Agricultural Research Center in Maricopa, Arizona, in collaboration with scientists at Cornell University and Brigham Young University, have identified a total of 22 omega-3 fatty acid desasturase genes in cotton progenitor (Gossypium herbaceum and G. raimondii) and modern Upland cotton (G. hirsutum) species. The omega-3 desaturases are known to be important in determining cold tolerance in crop plants, and availability of these sequences will enable future studies aimed at identifying specific alleles for these genes, in a diverse cotton population, that associate with improved cold tolerance in cotton. These alleles would provide molecular markers for introducing this important trait into commercial cotton varieties.