Characterization, Genetic Analyses, and Identification of QTLs Conferring Metabolic Resistance to a 4-Hydroxyphenylpyruvate Dioxygenase Inhibitor in Sorghum (Sorghum bicolor)

Abstract

Postemergence grass weed control continues to be a major challenge in grain sorghum [Sorghum bicolor (L.) Moench], primarily due to lack of herbicide options registered for use in this crop. The development of herbicide-resistant sorghum technology to facilitate broad-spectrum postemergence weed control can be an economical and viable solution. The 4-hydroxyphenylpyruvate dioxygenase-inhibitor herbicides (e.g., mesotrione or tembotrione) can control a broad spectrum of weeds including grasses, which, however, are not registered for postemergence application in sorghum due to crop injury. In this study, we identified two tembotrione-resistant sorghum genotypes (G-200, G-350) and one susceptible genotype (S-1) by screening 317 sorghum lines from a sorghum association panel (SAP). These tembotrione-resistant and tembotrione-susceptible genotypes were evaluated in a tembotrione dose–response [0, 5.75, 11.5, 23, 46, 92 (label recommended dose), 184, 368, and 736 g ai ha–1] assay. Compared with S-1, the genotypes G-200 and G-350 exhibited 10- and seven fold more resistance to tembotrione, respectively. To understand the inheritance of tembotrione-resistant trait, crosses were performed using S-1 and G-200 or G-350 to generate F1 and F2 progeny. The F1 and F2 progeny were assessed for their response to tembotrione treatment. Genetic analyses of the F1 and F2 progeny demonstrated that the tembotrione resistance in G-200 and G-350 is a partially dominant polygenic trait. Furthermore, cytochrome P450 (CYP)-inhibitor assay using malathion and piperonyl butoxide suggested possible CYP-mediated metabolism of tembotrione in G-200 and G-350. Genotype-by-sequencing based quantitative trait loci (QTL) mapping revealed QTLs associated with tembotrione resistance in G-200 and G-350 genotypes. Overall, the genotypes G-200 and G-350 confer a high level of metabolic resistance to tembotrione and controlled by a polygenic trait. There is an enormous potential to introgress the tembotrione resistance into breeding lines to develop agronomically desirable sorghum hybrids.

Identification and Characterization of Mesotrione-Resistant Grain Sorghum [Sorghum bicolor (L.) Moench]: A Viable Option for Postemergence Grass Weed Control

“…Sorghum seeds were germinated on solidified agar medium in Petri dishes. The germinated seedlings were transferred to a solidified agar medium supplemented with 3 μM of analytical grade mesotrione (Sigma-Aldrich Inc. St. Louis, MO) following previously reported procedures . Mesotrione concentration for the in vitro screening was determined based on a preliminary assay, in which 3 μM mesotrione was required for 50% visible injury in Pioneer 84G62 (data not shown).…”

“…The dry biomass (% of nontreated) from the CYP-inhibitor recovery assay was subjected to ANOVA (analysis of variance) followed by Fisher’s least significant difference to separate means. For determining the inheritance of mesotrione resistance, chi-square (χ2) goodness of fit test was used to fit to a single dominant gene model by comparing the observed and expected segregation frequencies of mesotrione-resistant or -susceptible plants; all statistical analyses were performed as described in our previous publication …”

“…The germinated seedlings were transferred to a solidified agar medium supplemented with 3 μM of analytical grade mesotrione (Sigma-Aldrich Inc. St. Louis, MO) following previously reported procedures. 18 Mesotrione concentration for the in vitro screening was determined based on a preliminary assay, in which 3 μM mesotrione was required for 50% visible injury in Pioneer 84G62 (data not shown). Sorghum response to mesotrione treatment was evaluated visually (% injury) 2 weeks after transferring to mesotrionecontained medium based on a 0 to 100% rating scale (0% is no injury and 100% is complete death; Figure 1).…”

Co-expression of stress-responsive regulatory genes, MuNAC4, MuWRKY3 and MuMYB96 associated with resistant-traits improves drought adaptation in transgenic groundnut (Arachis hypogaea l.) plants

“…All the physiological and biochemical experiments were conducted in three biologically independent experiments, statistical analyses were performed using R version 4.2.0, and ANOVA was performed using the R package agricolae with Fisher’s LSD test to separate means and significance at P ≤ 0.05 ( de Mendiburu, 2014 ; Pandian et al., 2020 ). Data presented are mean values and standard error ( ± SE).…”

Current status and prospects of herbicide‐resistant grain sorghum (Sorghum bicolor)

“…This method was used in grain sorghum to map QTLs for several biotic and abiotic stress resistance, including herbicide resistance 73–75 . We recently identified six QTLs responsible for tembotrione resistance in sorghum using the linkage mapping technique conferring ~3× resistance compared to commercial hybrid 34 . Earlier, a QTL associated with mesotrione and/or isoxazole herbicide resistance was identified in soybean 76…”