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United States Department of Agriculture

Agricultural Research Service


Location: Crop Genetics Research

2011 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
Eleven Pima varieties were tested for earliness, lint yield, and quality at Stoneville. The best performing Pima lines will be crossed with Delta lines to transfer their superior fiber quality. To broaden the genetic base of Delta cotton, F3 of twelve Gossypium (G.)hirsutum and G. barbadense lines crossed with best Delta cotton were selected for lint yield and quality and the nectariless trait. To break the negative linkages between lint yield and fiber strength, a polycross involving eight diverse cotton germplasm was made. F1 were promoted to F2 and second set of the polycross was made in the winter nursery at Mexico. The final set of the polycross was made in the field this year. A new set of polycrosses, involving different parents, was also started in the field. Ultimately, through a series of selections, lines that combine both high yield and high strength will be developed. Selections from chemically mutated MD 90ne and MD 15OP that showed significant variation for fiber length and strength were grown as progeny rows in the field. Cotton variety with partially naked seed traits gin faster and have lower short fiber content and neps because of the lower wear and tear on the fiber caused by ginning. Allelism tests were performed to determine if partially naked seed mutant germplasm ‘SC 9023 NS’ has similar or different gene(s) for nakedness than germplasm previously identified with naked seed. One hundred and sixty seven segregating F4 and F5 lines from five separate crosses were screened for lint yield, fiber quality, and the presence of the nectariless trait. In a collaborative project between three ARS research units, three parents with low and high net energy ginning requirements and two parents that have low and fast ginning rates were crossed to generate the populations needed for a molecular study. Nine selected exotic germplasm lines from ‘Species Polycross’ (SP) and JohnCotton (JC) were crossed with five high yield cultivars in a factorial design. These crosses were designed to introgress desirable exotic genes into high yield cultivars for genetic improvement of both lint yield and fiber quality. F2 and F3 derived from these crosses were grown under multiple environments. The populations will be evaluated for lint yield and fiber quality to identify genotypes with high lint yield and high quality, determine genetic values and genetic associations of fiber properties including neppiness traits, and reveal epistatic effects with exotic genes. In a study designed to analyze heritability of yield components such as lint percent and AFIS-measured properties such as fiber neps, F3 plants of two single crosses, FiberMax 832 x SP205 and MD15 x SP156, were planted with their parents. These F3 plants will be harvested to determine yield components and fiber properties. The top 5% of F3 plants will be selected for lint percentage and fiber neps.

4. Accomplishments
1. Germplasm potential for genetic improvement of lint yield and fiber quality. In order for cotton produced in the U.S. to be competitive in world markets, the fiber quality needs to be improved; use of exotic germplasm in breeding populations may be one method to improve the most important fiber traits. ARS scientists at Stoneville, MS, determined the potential of the Species Polycross (SP)and John Cotton (JC) populations for genetic improvement of both lint yield and fiber quality by detecting combining ability of exotic genes with modern cultivars. Twelve exotic germplasm lines were crossed with four cultivars and the 48 F2 hybrids were evaluated under multiple environments. General combining abGility (GCA) effects were significant for lint yield and fiber properties. Positive GCA effect for lint yield and favorable GCA effects for multiple fiber properties were identified in SP156, SP192, SP205, SP224 and JC65. These germplasm lines can be used as parents for genetic improvement of both lint yield and fiber quality. Introgression of these exotic genes into Upland cotton cultivars will make industry more competitive in global market by improving fiber quality and maintaining productivity.

2. Cotton genotypes that require less energy to gin and gin faster identified. Reducing ginning energy costs is essential since this has become a major expense to cotton ginners. ARS scientists at Stoneville, MS, evaluated forty-six conventional and transgenic genotypes for energy required for ginning. Net ginning energy requirements ranged from 7.5 to 12 Watthour per kilogram lint and ginning rates ranged from 2.37 to 3.35 gram lint per second. The fast ginner genotypes also had better quality (low short fiber content and neps). Introduction of the ginning efficiency trait into Delta lines with good yield, good quality and the nectariless trait (which confers resistance to the tarnished plant bug) will boost the value of cotton produced in the Delta.

3. Combining ability for neps, seed coat fragments, and motes. Forty-eight F2 hybrids derived from 12 exotic germplasm lines and 4 cultivars were evaluated. Significant genotypic variations for nep and mote were identified in F2 hybrids. There was one germplasm line, SP156, detected with favorable general combining ability effects for reducing neps and motes, increasing lint yield, and improving other fiber properties such as fiber length, short fiber content, and immature fiber content. This line can be used as parent in breeding for genetic improvement of neps and motes. Its introgression into Upland cotton will improve cleanability of U.S. cotton fibers and thus make cotton growers more profitable.

4. Predict hybrid performance using molecular markers. Relationships between SSR markers-based genetic distance (GD) and F2 hybrid performance in cotton were determined in 48 F2 hybrids derived from crosses between 4 cultivars and 12 exotic germplasm lines, i.e., (SP) and John Cotton (JC) lines. Significant population differentiation was detected between JC germplasm and cultivars. Moderate correlations were detected between genetic distance and fiber properties in JC-derived F2 hybrids. Faster progress in cotton breeding can occur when crosses are made between parents from genetically differentiated groups in cotton germplasm.

Review Publications
Bechere, E., Auld, D.L., Krifa, M., Smith, C.W., Cantrell, R.G. 2011. Registration of TTU-0782 upland cotton germplasm line with superior fiber quality. Journal of Plant Registrations. 5(2):207-2010.

Bechere, E., Boykin Jr, J.C., Meredith Jr, W.R. 2011. Evaluation of cotton genotypes for ginning energy and ginning rate. Journal of Cotton Science. 15:11-21.

Zeng, L., Meredith Jr, W.R. 2010. Germplasm potential for continuing improvement of fiber quality in upland cotton: combining ability for lint yield and fiber quality. Crop Science. 51:60-68.

Last Modified: 06/28/2017
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