|Mendu, Venugopal - TEXAS TECH UNIVERSITY|
|Ritchie, Glen - TEXAS TECH UNIVERSITY|
Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2018
Publication Date: 7/10/2018
Citation: Witt, T.W., Ulloa, M., Pelletier, M.G., Mendu, V., Ritchie, G.L. 2018. Exploring ethyl methaneSulfonate (EMS) treated cotton (Gossypium hirsutum L.) to improve drought tolerance. Euphytica. 214:123.
Interpretive Summary: The current levels of cotton production are under threat by the fact that the climate is getting hotter and drier and aquifers, such as the Ogallala, are being depleted faster than they can be replenished. In addition, in the Texas High Plains often unpredictable and extended periods between rainfall events can lead to a reduction in yield and fiber quality. Therefore, there is a need for drought resistant upland cotton germplasm. However, there may be insufficient genetic diversity among current cotton lines. Scientists from ARS (Lubbock, Texas) and Texas Tech University created three populations of mutant cotton. These populations were examined for four agronomic and thirteen morphological traits under multiple irrigation rates. This research established the importance of different traits for the selection of drought tolerant lines and identified a few lines with potential for possible public germplasm release.
Technical Abstract: The Texas High Plains often has extended periods between rainfall events, which can lead to a reduction in the yield and fiber quality of cotton (Gossypium hirsutum L.). It is known that cultivated cotton suffers from low levels of genetic diversity due to the over-use in breeding of similar gene pools or elite germplasm, which may hinder breeding for drought tolerance. In this study, for the first time the novel variability or genetic diversity of morphological and agronomic traits possibly created by the chemical mutagen Ethyl MethaneSulfonate (EMS) was assessed and explored to improve drought tolerance in cotton (G. hirsutum L.) by traits’ response/plant stress with different irrigation regimes. EMS is a chemical mutagen that has been shown to cause point mutations in the DNA of many model plants and crop species. Three EMS treated lines were advanced from the M1 to M4 generation as bulk-harvested populations. A diverse selection scheme was applied to capture most of the genetic trait-variability or genetic diversity and superior lines in these populations. In 2014-2016 the diversity of these populations was evaluated based on four agronomic and thirteen morphological traits to determine differences in response to multiple irrigation rates. Analyses of these traits showed statistically significant (p = 0.05) differences between and within populations when compared to the original non-treated EMS source, with most of the variability being observed in the high irrigation rate. However, none of the EMS treated populations had significantly (p = 0.05) better lint yield than the commercial cultivar (control) in 2016. EMS yield performance was possibly constrained by the applied diverse selection scheme of this study. Traits such as total number of bolls, bolls retained at node 7 and below, and those retained between nodes 8 and 12, and bolls retained at node of first fruiting branch may be predictors to improve cotton production (yield) in water limiting environments. This research established the importance of different traits for the selection of drought tolerant lines and identified a few lines with potential for possible public germplasm release.