Osman A. Gutiérrez

Effects of Chromosome-Specific Introgression in Upland Cotton on Fiber and Agronomic Traits

Interspecific chromosome substitution is among the most powerful means of introgression and steps toward quantitative trait locus (QTL) identification. By reducing the genetic “noise” from other chromosomes, it greatly empowers the detection of genetic effects by specific chromosomes on quantitative traits. Here, we report on such results for 14 cotton lines (CS-B) with specific chromosomes or chromosome arms from G. barbadense L. substituted into G. hirsutum and chromosome-specific F2 families. Boll size, lint percentage, micronaire, 2.5% span length, elongation, strength, and yield were measured by replicated field experiments in five diverse environments and analyzed under an additive–dominance (AD) genetic model with genotype and environment interaction. Additive effects were significant for all traits and dominance effects were significant for all traits except 2.5% span length. CS-B25 had additive effects increasing fiber strength and fiber length and decreasing micronaire. CS-B16 and CS-B18 had additive effects related to reduced yields. The results point toward specific chromosomes of G. barbadense 3-79 as the probable locations of the genes that significantly affect quantitative traits of importance. Our results provided a scope to analyze individual chromosomes of the genome in homozygous and heterozygous conditions and thus detected novel effects of alleles controlling important QTL.

Genetic variance components and genetic effects among eleven diverse upland cotton lines and their F2 hybrids.

Selecting high yielding upland cotton, Gossypium hirsutum L. lines with improved fiber quality is a primary breeding goal. A diverse set of ten cultivars and one breeding line were crossed in a half diallel. Parents and F2 hybrids were grown in three environments at Mississippi State, MS. Ten agronomic and fiber traits were analyzed by a mixed linear model approach based on the additive-dominance genetic model. Variance component, genetic effects and genetic correlations were calculated. ‘Acala Ultima’ was a desirable general combiner for fiber length, uniformity, strength, micronaire, lint percentage, and boll weight. ‘FiberMax 966’ was a desirable general combiner for fiber length, uniformity, strength, and all agronomic traits. ‘Tamcot Pyramid’ and M240 were poor general combiners for both fiber and agronomic traits. ‘Coker 315’ was a good general combiner for fiber length, uniformity, micronaire, boll weight, boll number, and yield. Heterozygous dominance effects were associated with several crosses, which suggest their use as hybrids.

Status of the USA cotton germplasm collection and crop vulnerability.

The National Plant Germplasm System (NPGS) is a cooperative effort among State, Federal and Private organizations aimed at preserving one of agriculture’s greatest assets: plant genetic diversity. The NPGS serves the scientific community by collecting, storing, and distributing germplasm as well as maintaining a searchable database of trait descriptors. Serving the NPGS, a Crop Germplasm Committee (CGC) is elected for each crop and is comprised of a group of scientists concerned with development, maintenance, characterization, and utilization of germplasm collections. Each CGC serves in an advisory role and provides a status report every seven years to determine scientific efforts, adequacy of germplasm base representation, and progress in breeding through utilization of germplasm. In addition, each committee can call attention to areas of concerns regarding facilities and staffing associated with the maintenance, collection, and taxonomic activities for a specific crop within the system. The following report was developed by the CGC for cotton and provides a record of collections, activities, concerns, crop vulnerabilities, and recommendations associated with the cotton collection for the period 1997–2005. Information provided within this document is a much expanded and detailed description of a report provided to the NPGS and includes the most exhaustive citation of germplasm depositions and research activity descriptions available anywhere in the USA for this time period. This documentation will be a valuable resource to breeders, geneticists, and taxonomists with an interest in this important food and fiber crop.