Absorption and translocation of [14C]2,4-dichlorophenoxyacetic acid in herbicide-tolerant chromosome substitution lines of Gossypium hirsutum L

Authors: PEREZ, LOIDA - Mississippi State University; YUE, ZIMING - Mississippi State University; Saha, Sukumar; DEAN, JEFFREY - Mississippi State University; Jenkins, Johnie; STELLY, DAVID - Texas A&M University; TSENG, TE-MING - Mississippi State University

Submitted to: Frontiers in Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2022
Publication Date: 10/6/2022
Citation: Perez, L.M., Yue, Z., Saha, S., Dean, J.F., Jenkins, J.N., Stelly, D.M., Tseng, T.P. 2022. Absorption and translocation of [14C]2,4-dichlorophenoxyacetic acid in herbicide-tolerant chromosome substitution lines of Gossypium hirsutum L. Frontiers in Agronomy. https://org.doi/doi: 10.3389/fagro.2022.936119.
DOI: https://doi.org/10.3389/fagro.2022.936119

Interpretive Summary: Upland cotton is sensitive to 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide commonly used in weed management of the cotton fields. The identification of potentially 2,4-D tolerant cotton chromosome substitution (CS) lines and understanding genetic mechanisms associated with 2,4-D herbicide tolerance provide a significant step into the development and genetic improvement of upland cotton to reduce yield loss caused by 2,4-D herbicide effects including the drifts effects from neighboring fields. Experiments were conducted to understand the possible mechanism of herbicide tolerance in 2,4-D herbicide tolerant chromosome substitution (CS) lines compared with the TM-1, the 2,4-D herbicide susceptible parent of the CS lines as control, using radio isotope labeled [14C] 2,4-D solution on cotton. Percent absorption rate and translocation patterns of the 14C-labeled herbicide application at 5.17 kBq at 6 to 48 hours after treatment (HAT) were determined after spraying the herbicide on the leaf in greenhouse grown cotton plants. The tolerant cotton CS lines showed 15-19% [14C]2,4-D uptake while TM-1 exhibited a reduced uptake of only 1.4% [14C]2,4-D at 24 HAT. Distribution of the absorbed [14C]2,4-D showed that 2-5% was translocated outside the treated leaf in the tolerant CS lines, where as in TM-1, 77% of the herbicide was translocated above and below the treated leaf, which contrasted with the reduced translocation of 14C-labeled herbicide observed in the tolerant CS lines. Results suggested that the tolerant CS lines with reduced translocation possibly provided a mechanism to affect other tissues after absorbing the herbicide from the leaf surface. Interestingly, one of the tolerant CS lines showed a restricted movement of 14C below the treated leaf at 6 to 48 HAT, suggesting a different mechanism of herbicide tolerance compared to the other 2,4-D tolerant CS line. This finding is the first report on upland cotton demonstrating a complex differential uptake and translocation of [14C]2,4-D in cotton CS lines.

Technical Abstract: Upland cotton is sensitive to 2,4-dichlorophenoxyacetic acid (2,4-D), and the identification of po-tentially 2,4-D tolerant cotton chromosome substitution (CS) lines and understanding tolerance mechanisms provide a significant step into the development and genetic improvement of upland cotton to reduce yield loss caused by 2,4-D herbicide effects including the drifts. Experiments were conducted to understand the possible mechanism of herbicide tolerance in CS-T04-15, CS-T07, and CS-B15sh, 2,4-D herbicide-tolerant cotton CS lines compared with TM-1, the 2,4-D herbicide sus-ceptible recurrent parent of the CS line as control, using [14C]2,4-D. Percent absorption rate and translocation patterns of the 14C-labeled herbicide application at 5.17 kBq at 6 to 48 hours after treatment (HAT) were determined. The tolerant cotton CS lines showed 15-19% [14C]2,4-D uptake while TM-1 exhibited a reduced uptake of only 1.4% [14C]2,4-D at 24 HAT. Distribution of the absorbed [14C]2,4-D showed that 2-5% was translocated outside the treated leaf. In TM-1, 77% of the herbicide was translocated above and below the treated leaf, contrasting with the novel reduced translocation of 14C-labeled herbicide observed in the tolerant CS lines. Interestingly, CS-T04-15 showed a restricted movement of 14C below the treated leaf at 6 to 48 HAT, suggesting a different translocation mechanism of herbicide tolerance among the tolerant CS lines. This finding is the first report on upland cotton demonstrating a complex differential uptake and translocation as-sociated with herbicide tolerance for [14C]2,4-D in cotton CS lines.