Metabolic Pathway of Topramezone in Multiple-Resistant Waterhemp (Amaranthus tuberculatus) Differs From Naturally Tolerant Maize

Waterhemp [Amaranthus tuberculatus (Moq.) Sauer] is a problematic dicot weed in maize, soybean, and cotton production in the United States. Waterhemp has evolved resistance to several commercial herbicides that inhibit the 4-hydroxyphenylpyruvate-dioxygenase (HPPD) enzyme in sensitive dicots, and research to date has shown that HPPD-inhibitor resistance is conferred by rapid oxidative metabolism of the parent compound in resistant populations. Mesotrione and tembotrione (both triketones) have been used exclusively to study HPPD-inhibitor resistance mechanisms in waterhemp and a related species, A. palmeri (S. Wats.), but the commercial HPPD inhibitor topramezone (a pyrazolone) has not been investigated from a mechanistic standpoint despite numerous reports of cross-resistance in the field and greenhouse. The first objective of our research was to determine if two multiple herbicide-resistant (MHR) waterhemp populations (named NEB and SIR) metabolize topramezone more rapidly than two HPPD inhibitor-sensitive waterhemp populations (named SEN and ACR). Our second objective was to determine if initial topramezone metabolite(s) detected in MHR waterhemp are qualitatively different than those formed in maize. An excised leaf assay and whole-plant study investigated initial rates of topramezone metabolism (<24 h) and identified topramezone metabolites at 48 hours after treatment (HAT), respectively, in the four waterhemp populations and maize. Results indicated both MHR waterhemp populations metabolized more topramezone than the sensitive (SEN) population at 6 HAT, while only the SIR population metabolized more topramezone than SEN at 24 HAT. Maize metabolized more topramezone than any waterhemp population at each time point examined. LC-MS analysis of topramezone metabolites at 48 HAT showed maize primarily formed desmethyl and benzoic acid metabolites, as expected based on published reports, whereas SIR formed two putative hydroxylated metabolites. Subsequent LC-MS/MS analyses identified both hydroxytopramezone metabolites in SIR as different hydroxylation products of the isoxazole ring, which were also present in maize 48 HAT but at very low levels. These results indicate that SIR initially metabolizes and detoxifies topramezone in a different manner than tolerant maize

PROJECT MANAGEMENT FOR THE STATE-GOVERNED GEOLOGICAL EXPLORATION OF MINERAL RESOURCES

The relevance of the research. Creating high-efficient and innovation-oriented system of studying the subsoil and the mineral resource base is one of the priority areas of developing the geological sphere. The purpose of the present study is to substantiate the rationale for the adoption of the project management methods for the exploration work. Research methods: method of system analysis, method of comparison and analogies, and method of scientific generalization. The results and their application. This article deals with the content of the main standard legislative documents which determine the strategy and lines of the country’s geological sector development in the nearest future. The article discloses the purposes and their strategic objectives and the content of the state program of the Russian Federation called “Reproduction and use of natural resources”. The resource support of the program and its subroutines is also revealed. The structure of geological industry management in modern conditions is presented. The main activities for restructuring of the geological industry are set out. They include the following points. The transformation of the Federal state unitary enterprises of information and expert profile, the advancement of scientific organizations engaged in scientific and analytical support of performed public functions. These functions are concerned with the geological study of subsoil and reproduction of the mineral resource base, as well as improving its management. The consolidation of specialized geological organizations on the types of exploration and mining, and also the main results of reorganization of the enterprises is taken into account. All of the aforementioned is subordinated to and is conducted by the Federal Agency for subsoil management. The shortcomings of the current system of management of works on the state geological study of the subsoil were revealed at the expense of the Federal budget. The necessity of introducing the project management methods to improve the efficiency of the state management of exploration was proven. The essence of the project-oriented system of the exploration works state management is considered. The model of the geological industry management system with the allocation of sectoral projects was adduced. The organizational structure and the structure of the activities of project participants, including planned and unscheduled activities was also gi-ven. We defined the nature of the management processes divided into five groups, the content of the control units of the sectoral project and the geological exploration management matrix. This was determined in the framework of the sectoral project. The proposed project-oriented control system of hydraulic fracturing, which varies depending on the environment, will allow the most effective implementation of the functions of state regulation in the mineral sector

Carfentrazone-ethyl resistance in an Amaranthus tuberculatus population is not mediated by amino acid alterations in the PPO2 protein.

To date, the only known mechanism conferring protoporphyrinogen IX oxidase (PPO)-inhibitor resistance in waterhemp (Amaranthus tuberculatus) is a glycine deletion in PPO2 (ΔG210), which results in cross-resistance to foliar PPO-inhibiting herbicides. However, a metabolism-based, HPPD-inhibitor resistant waterhemp population from Illinois (named SIR) was suspected of having a non-target site resistance (NTSR) mechanism due to its resistance to carfentrazone-ethyl (CE) but sensitivity to diphenylethers (DPEs). In greenhouse experiments, SIR sustained less injury than two PPO inhibitor-sensitive populations (WCS and SEN) after applying a field-use rate of CE, and after initial rapid necrosis, regrowth of SIR plants was comparable to a known PPO inhibitor-resistant population (ACR) possessing the ΔG210 mutation. Dose-response analysis determined 50% growth reduction rates in CE-resistant (SIR and ACR) and sensitive (SEN) waterhemp populations, which showed SIR was 30-fold resistant compared to SEN and two-fold more resistant than ACR. Deduced amino acid sequences derived from SIR PPX2 partial cDNAs did not contain the ΔG210 mutation found in ACR or other target-site mutations that confer PPO-inhibitor resistance previously reported in Palmer amaranth (Amaranthus palmeri). Although several SIR cDNAs contained amino acid substitutions, none were uniform among samples. Additionally, SIR plants treated with malathion and CE showed a significant reduction in biomass accumulation compared to CE alone. These results indicate robust CE resistance in SIR is not mediated by amino acid changes in the PPO2 protein, but instead resistance may be conferred through a NTSR mechanism such as enhanced herbicide metabolism