Limited induction of ethylene and cyanide synthesis are observed in quinclorac-resistant barnyardgrass (Echinochloa crus-galli) in Uruguay

Abstract

Barnyardgrass [Echinochloa crus-galli (L.) P. Beauv] is the foremost weed in rice (Oryza sativa L.) systems, and its control is crucial to successful rice production. Quinclorac, a synthetic auxin herbicide, has been used effectively to manage E. crus-galli. However, occurrences of quinclorac-resistant genotypes are frequently reported, and its resistance evolution has led to questions about the continued utility of quinclorac for grass control. Identification of the resistance mechanism(s) of resistant genotypes will facilitate development of integrated weed management strategies that sustain quinclorac use for management of E. crus-galli. We evaluated the responses to quinclorac of two contrasting genotypes: E7 (resistant, R) and LM04 (susceptible, S). Quinclorac induced ethylene and cyanide biosynthesis in the S-genotype. Both genotypes responded similarly to an increasing application of exogenous 1-carboxylic acid aminocyclopropane (ACC) and potassium cyanide, and their growth was inhibited at higher doses. The key mechanism for cyanide (HCN) detoxification in plants, β-cyanoalanine synthase (β-CAS) activity, was evaluated in both genotypes, and no significant difference was observed in the basal activity. However, quinclorac significantly induced β-CAS–like activity in the S-genotype, which is consistent with the increased synthesis of ethylene and cyanide. This work suggests that the resistance to quinclorac of the E7 R-genotype is likely related to an alteration in the auxin signal transduction pathway, causing a lower stimulation of ACC synthase and, therefore, limited synthesis of ethylene and HCN after quinclorac treatment.

Transcriptomic Change in the Effects of Dichloroquinolinic Acid on the Development and Growth of Nicotiana tabacum

“…However, the extensive application of the auxin-type herbicide dichloroquinolinic acid (3,7-dichloro-8-quinolinecarboxylic acid) may be harmful to rice [1], tomato [2], maize [3], and tobacco. Additionally, the inclusion of dichloroquinolinic acid in the growth medium leads to a decrease in the total chlorophyll content and an increase in ethylene/cyanide biosynthesis in maize leaves [4,5]. Dichloroquinolinic acid can also increase the level of endogenous abscisic acid and restrict photosynthetic CO2 fixation [6].…”

Proteomic Analysis Comparison on the Ecological Adaptability of Quinclorac-Resistant Echinochloa crus-galli

“…Quinclorac (3,7-dichloro-quinoline-carboxylic acid) has, in the past two decades, been used as an excellent herbicide against paddy field E. crus-galli . Prolonged quinclorac exposure has caused herbicide-driven selective pressure [ 6 ], rapidly resulting in the development of resistance in E. crus-galli and exacerbating the loss of yield and rice quality [ 7 ]. Thus, understanding the molecular mechanism of E. crus-galli resistance to quinclorac is not only essential for controlling the development of their resistance but also for improving the rice yield and quality.…”