Paper Details

PJB-2025-79

Cross resistance of fenoxaprop-p-ethyl resistant Phalaris minor Retz. to clodinafop-propargyl: understanding physiological and molecular mechanism of ACCase resistance

Amina Iftikhar, Ahmed Fahem Jabbar, Asmaa Mohammed Dheyab, Muhammad Ather Nadeem, Naila Farooq, Bilal Ahmad Khan, Ali Zohaib and Tasawer Abbas
Abstract

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Spread of herbicide resistant Phalaris minor is a key issue for sustainable wheat production around the globe. The response of fenoxaprop-p-ethyl resistant P. minor biotypes to clodinafop-propargyl was evaluated using the classical bioassay. Results revealed fenoxaprop-p-ethyl resistant P. minor biotypes (PM FSD 1 and PM MBD 5) have developed cross resistance to clodinafop-propargyl. LD50 values of cross-resistant biotypes were 57.18 and 90.70 g a.i. ha^-1 compared to the susceptible biotype (25.76 g a.i. ha^-1). The level of cross-resistance for PM FSD 1 and PM MBD 5 was 2.22 and 3.52. Physiological and molecular mechanisms of ACCase resistance in P. minor were studied by extracting ACCase enzyme followed by spectro-photometric assay and DNA extraction followed by SDS-PAGE and western blotting, respectively. The results revealed that more ACCase activity (2.49 nmol HCO^-3 mg^-1 protein min^-1) was recorded in PM MBD 5 followed by PM FSD 1 (resistant biotypes). In contrast, less ACCase activity (0.95 nmol HCO^-3 mg^-1 protein min^-1) was observed in susceptible biotypes. All the resistant biotypes had many folds more fenoxaprop-p-ethyl dose needed to inhibit 50% ACCase activity compared to susceptible ones. Among resistant biotypes, PM MBD 5 had the highest I50 value (9.35µM) and maximum protein concentration (0.69 mg ml^-1). Translation of the DNA sequence to the amino acid sequence showed that susceptible biotype had tryptophan (Trp, W) amino acid while resistant biotypes had cysteine (Cys, C) amino acid. Cysteine amino acid gave the resistance against ACCase-inhibiting herbicides. Confirmation of cross-resistance and novel insights into the physiological mechanisms of ACCase resistance will help to develop effective strategies for sustainable management of P. minor

To Cite this article: Iftikhar, A., A.F. Jabbar, A.M. Dheyab, M.A. Nadeem, N. Farooq, B.A. Khan, A. Zohaib and T. Abbas. 2026. Cross resistance of fenoxaprop-p-ethyl resistant Phalaris minor Retz. to clodinafop-propargyl: understanding physiological and molecular mechanism of ACCase resistance. Pak. J. Bot., 58(2): DOI: http://dx.doi.org/10.30848/PJB2026-2(5)  
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