Location: Crop Genetics Research2010 Annual Report
1a. Objectives (from AD-416)
Objective 1 – Develop new and improved combinations of yield and fiber traits and investigate the basic genetic factors related to the improved cottons. Objective 2 – Evaluate populations involving introgressed genes from wild species for agronomic acceptance and determine their genomic relationships. Objective 3: - Identify physiological traits that confer improved yield and fiber quality and investigate new management systems that optimize the performance of diverse varieties through pairing them with alternative production strategies.
1b. Approach (from AD-416)
Assemble germplasms originating from other Gossypium strains, race stocks, species, and genetic-breeding populations. Using genomics and other new biotechnology tools combined with conventional methods, evaluate new germplasms for its potential in developing improved combinations of yield, fiber quality, and pest resistance cottons. Investigate the underlying causes of the negative associations of yield and fiber quality. Determine how the micro-climate and management impact improved yield and fiber quality. Characterize the genetic vegetative-reproductive growth patterns, crop maturity, leaf shape and the physiological variances that interact with crop management. Identify physiological and genetic systems that have potential for being more efficient in developing new cotton cultivar systems that are environmentally safe and results in more competitive USA cottons. Identify biomarkers associated with improved yield and fiber quality for marker assisted selections. In cooperation with other ARS laboratories, describe developmental mechanisms of cellulose synthesis and improved fiber traits. Important fiber traits are fiber length, short fiber content, bundle strength, fineness and maturity.
3. Progress Report
In 2009, evaluations were made for yield and fiber quality 153 progeny that were F5:6 progenies from the MD 25 germplasm. The progeny tests of these lines resulted in 17 lines being selected because of better than average yield and fiber quality, and the presence of the nectariless trait. This trait confers resistance to tarnished plant bugs. This insect results in the greatest cotton yield losses and accounts for most insecticide applications for any insect in the Mid South. Also chosen from this population were 25 lines with fiber yield exceeding the commercial checks and also having good fiber traits, length, strength, and micronaire. MD 25 and MD 9ne are being released as germplasm releases. In cooperative research with USDA-ARS-SRRC, New Orleans, LA, agronomic data were provided for 98 F2:3 progenies of BC8, F2:3 high strength cottons for genomic analysis. The selected trait in these studies is higher fiber bundle strength. The objective of this study is to determine the number of genes, their effects, and genetic identity. In another cooperative project with the Cotton Ginning Laboratory, USDA-ARS, Stoneville, MS, the possibility of selecting cotton lines that require less energy and gin faster is being explored. The possible desirable outcome of this research is reducing the ginning energy requirements, decrease time required to gin a given quantity of seed cotton, improve fiber length and decrease short fiber content. Also, the quantity of sulfuric acid needed for seed processing would be reduced. The first two years of research involving 46 genotypes show considerable genetic variation for energy requirements and time required to gin a given quantity of cotton. Data also shows a simple seed characteristic, seed fuzz, is negatively associated with ginning energy requirements and ginning time rate. Research in 2010 is being expanded to measure the genetic variability in F4 and F5 from crosses made with genetically different backgrounds. In a two-year study, a 4 X 12 combining ability study was conducted. The 48 populations involve four diverse cottons crossed with 12 selected polycross progeny selections. The polycross populations involve introductions from the wild tetraploid species. The genetic distance, as indicated by SSR genomic analyses, was variable as to its ability to select good combiners. Genetic distance among lines developed form the John Cotton polycross from Gossypium (G.) barbadense showed usability but genetic distance was not a good indicator of combining ability for lines derived from a tetraploid species polycross.
1. About 75% of Cotton Produced in the U.S.A. is Exported. These new customers require a better quality of cotton for a given price than has been generally, in the past, required of the U.S.A. Classing and Marketing systems. To be more competitive on a world market, the U.S.A. needs to improve its fiber length, length uniformity, strength, fineness, and decrease its short fiber content. The release of two germplasms is a big step for improving the U.S.A.’s cotton quality. These germplasms, MD 9ne and MD 25 have an unusually good combination of yield and fiber quality. In multi-state regional variety tests, these two entries have had above average yield and high fiber and yarn strength, and superior uniformity and short fiber content. This combination results in more efficient spinning, less fiber waste, and a more uniform fiber and textile. The two germplasms also are nectariless or segregating for the nectariless trait. The nectariless trait confers resistance to the tarnished plant bug. This insect results in more yield losses and accounts for most insecticide applied than any other insect in the Mid South. Use of the new germplasms in applied breeding programs will result in increased yields, better fiber quality and a reduction in insect losses and insecticide application. These two germplasms are already producing new cotton strains that have these improved characteristics.
Bechere, E., Auld, D.L., Dotary, P., Kebede, H.A. 2010. Registration of Four Upland Cotton (Gossypium hirsutum L.) Genetic Stock Mutants with Tolerance to Imazamox. Journal of Plant Registrations. 4:155-158
Zeng, L., Meredith Jr, W.R. 2010. Neppiness in an Introgressed Population of Cotton: Genotypic Variation and Genotypic Correlation. Journal of Cotton Science. 14:17-25.