Alleles conferring improved fiber quality from EMS mutagenesis of elite cotton genotypes

Abstract

Genetic improvements for many fiber traits are obtained by mutagenesis of elite cottons, mitigating genetic uniformity in this inbred polyploid by contributing novel alleles important to ongoing crop improvement. The elite gene pool of cotton (Gossypium spp.) has less diversity than those of most other major crops, making identification of novel alleles important to ongoing crop improvement. A total of 3,164 M5 lines resulting from ethyl methanesulfonate (EMS) mutagenesis of two G. hirsutum breeding lines, TAM 94L-25 and Acala 1517-99, were characterized for basic components of fiber quality and selected yield components. Across all measured traits, the ranges of phenotypic values among the mutant lines were consistently larger than could be explained by chance (5.27-10.1 for TAM 94 L-25 and 5.29-7.94 standard deviations for Acala 1517-99-derived lines). Multi-year replicated studies confirmed a genetic basis for these differences, showing significant correlations between lines across years and environments. A subset of 157 lines selected for superior fiber qualities, including fiber elongation (22 lines), length (22), lint percent (17), fineness (23), Rd value (21), strength (19), uniformity (21) and multiple attributes in a selection index (26) were compared to 55 control lines in replicated trials in both Texas and Georgia. For all traits, mutant lines showing substantial and statistically significant improvements over control lines were found, in most cases from each of the two genetic backgrounds. This indicates that genetic improvements for a wide range of fiber traits may be obtained from mutagenesis of elite cottons. Indeed, lines selected for one fiber trait sometimes conferred additional attributes, suggesting pleiotropic effects of some mutations and offering multiple benefits for the incorporation of some alleles into mainstream breeding programs.

EMS-mutated cotton populations suggest overlapping genetic control of trichome and lint fiber variation

“…Such an experiment would also test our tacit assumption that in most cases, the fiber traits are a pleiotropic consequence of the trichome mutations. It may be significant that mutations are particularly closely associated with MIC and ELON, which have relatively short histories of selection in cotton breeding programs and thus unfavorable alleles may still be frequent in the elite cotton gene pool, as we have previously suggested in introgression and mutant studies (Patel et al 2013;Zhang et al 2011).…”

Ethyl methanesulfonate mutant library construction in Gossypium hirsutum L. for allotetraploid functional genomics and germplasm innovation

“…It is commonly considered that mutagen doses inducing about 50% lethality (LD50) among M1 plants are appropriate due to their high mutation rates (Ke et al, 2019). In the few reported experiments of cotton treated with EMS, the experimenters followed previously published basic protocols (Herring et al, 2004;Patel et al, 2014). However, the cotton-specific optimized EMS treatment condition of the dose and duration of time for cottonseeds in EMS solution have not been determined (Lowery et al, 2007).…”

Irrigation’s effect and applied selection on the fiber quality of Ethyl MethaneSulfonate (EMS) treated upland cotton (Gossypium hirsutum L.)

“…One breeding method that has been used in the improvement of fiber quality involves the use of a mutagen such as Ethyl MethaneSulfonate (EMS) (Auld et al 2007;Brown et al 2012;Patel et al 2014). Previous studies reported that creating genetic diversity with EMS may improve fiber quality under well water conditions or non-stressed environments.…”