Location: Crop Genetics Research2013 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:
Progress made this year: Evaluation of 184 F3:4 progeny lines to determine selection response and correlated selection response among fiber traits continued. A two-year experiment was started to evaluate genetic variations in F2 and F3 populations derived from 2-way, 3-way, and double crosses. Experiment was continued to analyze effects of late planting on lint yield and fiber quality and breeding values to improve our knowledge of quantitative genetics of fiber traits and breeding methods for genetic improvement of lint yield and fiber quality and develop management options for cotton production by late planting. F1 of three Pima varieties crossed with Delta lines were backcrossed (BC) with the Delta lines (recurrent parents) to combine the superior quality of the Pima varieties with the high yield and adaptability of the Delta lines. The F2 of these crosses were also separated and planted as nectariless and nectaried. To break the negative linkages between lint yield and fiber strength, F2 and F3 of the two sets of polycrosses involving eight parents each were planted in the field to make a modified bulk. The F2 of the cross MD 15 X SG 747 was planted to continue to develop recombinant inbred lines to use in quantitative trait loci (QTL) analyses for marker assisted selection. Final BC3 and random cross 3 for the cross MD 15 X SG 747 will be made. In a collaborative project, the genetics of ginning efficiency (heritability, genetic advances from selection and genotypic correlations with other important traits) have been determined. To study combining ability of ginning efficiency, crosses were made between best and worst ginners, and the F2 was grown in the Mexico Winter Nursery to enable a replicated trial of the F2. A length uniformity index study was also initiated to evaluate to length distribution in Delta cotton with 18 entries planted at Stoneville, MS, Lubbock, TX, and Florence, SC. During the five years that project was conducted the following were accomplished: Significant genotypic variations for lint yield and fiber quality were detected in two exotic germplasm populations, Species Polycross (SP) and JohnCotton (JC), derived from multiple crosses among tetraploid Gossypium species. Selections for lint yield and fiber quality were made in SP and JC germplasm populations and nine germplasm lines with desirable combination of lint yield and fiber properties were selected and released. Three germplasm lines with superior yield, fiber quality and pest resistance were also released. A new random mating population was developed by multiple crosses of 12 SP and JC germplasm lines and 4 cultivars, followed by five generations of random mating and four generations of selfing, and will be used for genetic and breeding studies in the next five years project for introgression of the novel genes into Upland cotton. Thirty-nine marker-trait associations were identified by an association mapping in 260 SP germplasm lines using single sequence repeat (SSR) markers. These markers were registered in Cotton Database and available to cotton researchers worldwide.
1. Data from Regional High Quality Tests used to test location effects. Data from Regional High Quality Tests, conducted as part of the USDA-ARS National Cotton Variety Tests during 2003 and 2009, were used to analyze test locations based on genotype by environment effects on lint yield. ARS scientists at Stoneville, MS, grouped test locations for cotton yield stability in order to identify redundant test sites and identify weather variables attributed to genotype by environmental interactions. Results showed that Lubbock, TX, and Las Cruces, NM, were unique to other test locations. Test locations can be more reasonably arranged by increasing sites in the Plains and Western test regions and reducing sites in the Central, Delta, and East regions. Daily minimum temperature was a significant attribute of the genotype by environment interactions for lint yield in the early and late growing seasons of upland cotton cultivars. This result suggests that genetic improvement of cotton cultivars for tolerance to low temperature during the early and late growing season could increase yield stability.
2. Identification of a mutant population of cotton with improved fiber quality. Cotton has a narrow germplasm base that often limits success of breeding programs. The use of chemically induced mutants can alleviate some of these problems. An ARS scientist at Stoneville, MS, chemically mutated the germplasm line MD 15 and developed an improved population with higher fiber length and fiber strength. Cotton breeders from five universities and companies have requested and received seeds of this germplasm population to select individual plants that suit their individual breeding program.
3. Identification and registration of a naked-tufted cotton mutant with high lint turnout and high ginning efficiency. Naked seed cotton lines developed so far by breeders have low lint turnouts which translates into low lint yield. A naked-tufted cotton mutant called 9023n4t with high lint turnout, high ginning efficiency, and low short fiber content and low neps (fiber entanglement) was identified and submitted for registration by an ARS scientist at Stoneville, MS. This mutant can be included in cotton breeding programs to exploit its positive traits without the fear of adverse effect from low lint percent exhibited by other naked seed phenotypes identified so far.
Zeng, L., Wu, J., Bechere, E. 2013. Genetic effect and genetic values of fiber properties in F2 and F3 hybrids between germplasm lines and high yield cultivars. Euphytica. 459-469.