Location: Crop Germplasm Research2011 Annual Report
1a. Objectives (from AD-416)
Objective 1: Conserve and distribute a wide diversity of cotton genetic resources and associated information to researchers and breeders worldwide. Sub-objective 1.A: Strategically expand U.S. holdings of cotton genetic resources, especially wild relatives of cotton, through germplasm exchanges and plant explorations. Sub-objective 1.B: Maintain more than 10,000 cotton accessions in the active collection. Regenerate cotton accessions at the Cotton Winter Nursery (CWN) each year, with priorities determined by user input and by seed inventory and viability. Increase the proportion of the active collection backed-up at the National Center for Genetic Resources Preservation (NCGRP). Sub-objective 1.C: Distribute on request cotton accessions and information that meet the specific needs of researchers and breeders. Sub-objective 1.D: Collect and submit data to GRIN and CottonDB. Objective 2: Strategically evaluate (phenotype) cotton genetic resources for priority biotic and abiotic stress resistance, quality factors, and other priority agronomic traits. Sub-objective 2.A: Evaluate cotton accessions in the Cotton Winter Nursery for fiber properties (strength, length, micronaire, elongation). Sub-objective 2.B: Coordinate the cooperative evaluation of cotton genetic resources for other priority agronomic traits, such as resistance to various abiotic and biotic stresses. Sub-objective 2.C: Incorporate the evaluation data collected above into GRIN, CottonDB, and other genetic resource databases. Objective 3: Characterize the genetic variability in cotton genetic resources via genotyping with leading edge genetic marker technology. Sub-objective 3.A: Genotype priority cotton accessions with SSR genetic markers, and incorporate genotypic data into GRIN, CottonDB, and/or other databases. Sub-objective 3.B: With the genotypic information obtained above, measure genetic variation within and among cotton accessions. Sub-objective 3.C: Coordinate the cooperative DNA marker characterization of the cotton germplasm collection with a core subset of portable molecular markers developed by the sister project (6202-21000-030-00D).
1b. Approach (from AD-416)
To conserve and distribute a wide diversity of cotton genetic resources (Objective 1), 400-500 new accessions will be added to the collection – primarily through germplasm exchanges with national collections held in China, France, India, Russia, and Uzbekistan. Plant explorations will also be conducted as funds for this purpose are provided by the Plant Exchange Office section of the National Germplasm Resources Laboratory. Approximately 1,000 accessions (10% of the collection) will be regenerated each year, with priority for regeneration based upon age of seed and germination rate. We will distribute upwards of 4,000 accessions per year for a total worldwide distribution of approximately 20,000 accessions over the period of this project plan. To meet the goal of evaluating cotton genetic resources for priority biotic and abiotic stress resistance, quality factors, and other priority agronomic traits (Objective 2), basic descriptor data will be collected during the grow-outs for regeneration in the Cotton Winter Nursery or in our greenhouses and specific collaborations will be established to evaluate germplasm for responses to biotic and abiotic stresses. To facilitate incorporation of evaluation data into GRIN, CottonDB, and other genetic resource databases, methods of electronic data collection and downloading into appropriate databases will be developed and cooperative efforts with managers at the Database Management Unit will be established to create new and appropriate fields within the GRIN database. More detailed or complex data will be stored in the local database until GRIN establishes the proper formats for public display. Efforts to characterize the genetic variability of the collection via genotyping with genetic marker technology (Objective 3) are being pursued in cooperation with the sister project (6202-21000-030-00D), and are focused on developing a comprehensive set of 208 core DNA markers for evaluation. To evaluate the suitability of the markers, a standard panel of the U.S. Cotton Germplasm Collection is being used. When appropriate markers have been identified, the DNA marker profile of a preselected set of 384 accessions representing a subset of the U.S. Cotton Germplasm Collection will be scored. Genetic diversity and phylogenetic relationships will be evaluated using population genetic software such as NT-SYS and Arlequin. The 384 samples will be clustered using the computer package PAUP and/or the neighboring-joining method. Once a core set of DNA markers is established and validated on the selected subset of the U.S. Cotton Germplasm Collection, the markers will be made available to cooperators, and coordination will be provided to accomplish the work in an efficient manner to prevent duplication of effort. Standard use of the core DNA markers will enable all characterizations and evaluations of Gossypium germplasm to be pooled into a common, publicly available database for analysis and interpretation across different gene pools or germplasm sources.
3. Progress Report
To maintain and characterize the National Cotton Germplasm Collection, seed of nearly 2,300 accessions was increased in FY 2011, with about 90% of the increases being accomplished in the Cotton Winter Nursery in Mexico. The remainder was accomplished in field and greenhouse facilities at College Station. A large portion of these accessions had descriptors taken and fiber analysis performed. For the first time, digital photographic records were made of many of the accessions. Sixteen accessions were added to the collection in FY 2011 from elite germplasm whose plant protection status has expired. Seed requests in FY 2011 continued to be high, with 2030 accessions being distributed in response to requests from 99 individuals and institutions. In a project to characterize the genetic diversity of the cotton germplasm collection, genotyping of 2,300 accessions with 105 molecular SSR markers was completed through a cooperative effort with other ARS scientists at Stoneville, MS, and New Orleans, LA. Analysis of this very large data set is an ongoing effort of all cooperators. In a project to determine the genetic diversity of cotton cultivars in the cotton germplasm collection, we completed genotyping of 60 cultivars from North Africa, South Africa, China, and the U.S. A collaborative effort with Texas A&M University to characterize the phenotypic diversity of cultivars continues with data collection and analyses of agronomic and quality traits. In a collaborative project with other ARS scientists to identify/develop high and low oil content germplasm, second-year replicated yield trials were grown in College Station, TX, and Florence, SC, to evaluate seed oil index, fiber quality, and agronomic properties.
1. Regeneration and characterization of cotton accessions at the Cotton Winter Nursery. Seed of almost 10,000 cotton accessions must be renewed periodically to maintain the genetic diversity represented in the germplasm collection maintained by ARS, and to continue to provide cotton researchers worldwide with critical germplasm to facilitate their research and breeding needs. ARS scientists at College Station, TX, through management of the Cotton Winter Nursery in Mexico, increased more than 2,000 cotton accessions, representing about 20% of the entire collection. Descriptors were taken on all of the accessions. And in a move to utilize digital imagery to make information more available to users, a substantial percentage of the collection was documented via digital photography. The Cotton Winter Nursery remains as one of the most critical support operations for the worldwide cotton research and development communities.
2. Improved/diversified cotton fiber and agronomic traits. As spinning technology advances, the textile industry demands higher quality cotton fiber to meet the needs of the new technology. And as input costs increase, farmers demand higher yielding cotton to offset the increasing expenses of cotton production. Improving both fiber quality and yield are overarching goals of modern cotton breeding programs. ARS scientists at College Station, TX, established through detailed analysis of seven parents and their progeny that, though difficult, it was possible to increase lint yield and fiber quality simultaneously. However, the work also showed that greater progress can be made when improving these traits individually rather than attempting to improve them at the same time. This knowledge is highly important in development of new strategies for cotton improvement, as measured both by yield and fiber quality.
Hinze, L.L., Percy, R.G., Jones, D. 2010. Fiber quality of cultivars and breeding lines in the Cotton Winter Nursery and U.S. environments. Journal of Cotton Science. 14(3):138-144.