1a. Objectives (from AD-416)
1) Develop genetic resources and cropping practices that increase cotton water-use efficiency. 2) Develop new cotton genetic resources with improved fiber quality, lint yield stability, and adaptation. 3) Develop management techniques for cotton grown with conservation tillage after a winter biofuel crop.
1b. Approach (from AD-416)
Basic genomic and applied research will be conducted on improving cotton water use efficiency. In this research, molecular techniques will be used to search for genes that may provide more tolerance to water-deficit stress. Field studies will be conducted to screen cotton germplasm for water-deficit stress tolerance and to determine how agronomic practices affect plant water status. Contemporary plant breeding methods will be used to develop and release high yielding germplasm lines with improved fiber quality. Germplasm combining ability studies as well as studies determining genetic mechanisms for improved fiber quality will be conducted to accelerate the germplasm development program. We will evaluate cotton production potential when double cropped with winter crops harvested for biofuels. Winter crop biomass and energy content, cotton seedling establishment, and cotton fertility needs will be assessed.
3. Progress Report
Gene Identification Research: Two experiments were conducted to identify genes in cotton that are involved in plant water use. The first experiment focused on identifying the aquaporin genes in cotton. Aquaporin gene products are proteins in cell membranes that facilitate water movement in and out of cells. Our research identified 71 cotton aquaporin genes. The expression of some aquaporin genes depends on plant tissue types and/or soil water availability. The second experiment focused on identifying a broad set of genes that show expression patterns sensitive to soil water availability. Our research identified greater than 225 water sensitive genes. We anticipate that both research experiments will provide useful targets for the genetic improvement of water use efficiency in cotton. Genetic Improvement Research: Two experiments are currently being conducted with the ultimate goal of developing new cotton genetic resources with improved fiber quality, lint yield stability, and adaptation. The first experiment is evaluating the breeding combining ability of the high fiber quality and genetically diverse Pee Dee germplasm with cotton germplasm developed in numerous other U.S. cotton production areas. Preliminary analysis of two years of field data identifies specific Pee Dee germplasm lines that combine well with other U.S. cotton germplasm. This finding allows for the development of breeding offspring with high fiber quality and excellent lint yield potential. The second experiment is determining the genetic relationships between several germplasm sources of high fiber quality. Preliminary analysis of two years of field data suggests that these germplasm sources likely contain and transmit different genetic factors for high fiber quality that can be combined to further improve fiber quality. We anticipate that both research experiments will provide information and breeding populations to develop new cotton genetic resources with improved fiber quality, lint yield stability, and adaptation. Cropping Systems Research: A two-year study investigating the influence of nitrogen fertilizer rate on the root hydraulic conductivity of four cotton genotypes was conducted. Similar experiments were conducted in Florence, SC, and Stoneville, MS. All data have been collected and are currently being analyzed. Data were also collected for two years at two locations (Florence, SC, and Auburn, AL) to evaluate the potential of using winter cover crops as co-feedstocks with animal manures for pyrolysis. Biomass and energy content was measured on rye, wheat, oats, crimson clover, vetch, and Austrian winter pea. Preliminary analysis indicates that of six cover crops evaluated, rye appears to have the highest suitability of the cover crops for use as a co-feedstock, particularly because of its high biomass production potential. Data were also collected from a two-year study investigating the potential of using phosphorus recovered from swine waste water as a fertilizer source for cotton produced with conservation tillage following a rye cover crop that was harvested for biomass. Soil and plant data from this study are currently being analyzed.
1. Genetic improvement of the 70-year Pee Dee cotton germplasm program. After 70 years of cotton breeding activities, the Pee Dee cotton germplasm program has developed a unique and diverse collection of high fiber quality germplasm resources that continue to contribute to the development of current commercial cultivars. Using extensive field performance data collected over three years across four U.S. states, ARS researchers from Florence, South Carolina, estimated the Pee Dee cotton germplasm program’s level of genetic improvement following 70 years of cotton breeding. The research has two important implications for cotton breeders and producers. First, the research shows that the breeding methods used over 70 years have increased yield 3% per breeding cycle while simultaneously decreasing the negative relationship between yield and fiber quality. Second, the research provides cotton breeders an extensive litmus test of specific breeding methods that can be used to design new, knowledge-based breeding strategies to develop new and improved cotton cultivars. The research is expected to both improve cotton breeding efficiency and facilitate a broadening of the genetic base in cotton so that long-term genetic improvement can continue.
2. Development of a rapid screening technique for cottonseed oil and protein. Cottonseed oil and protein are economically important by-products of cotton fiber production. Traditional methods to measure cottonseed oil and protein have been dependent upon destructive, time-consuming, chemical-extraction-based procedures. In collaboration with the University of North Texas, ARS researchers in Florence, South Carolina, developed an accurate, rapid, and inexpensive nuclear magnetic resonance method to non-destructively quantify cottonseed oil and protein. The novel method offers a rapid screening tool that can be used to develop cotton germplasm with customized oil and protein profiles. Customized cottonseed oil and protein germplasm have potential to develop new cotton-based products.
Mi, X., Eskridge, K.M., Wang, D., Baenziger, P.S., Campbell, B.T., Gill, K.S., Dweikat, I. 2010. Bayesian mixture structural equation modelling in multiple-trait QTL mapping. Genetics Research. 92:239-250.