Pest Management Science (2021) 77, 194-201

Xia Yang, Heping Han, Jingjing Cao, Yongfeng Li, Qin Yu and Stephen B. Powles (2021)
Exploring quinclorac resistance mechanisms in Echinochloa crus-pavonis from China
Pest Management Science 77 (1), 194-201
Abstract:
BACKGROUND
Barnyardgrass (Echinochloa spp.) is a global weed in rice fields. Quinclorac is commonly used to control barnyardgrass. However, due to persistent use, quinclorac resistance has evolved. We obtained quinclorac-susceptible (QS) and -resistant (QR1, QR2) lines from the progeny of a single resistant E. crus-pavonis for a resistance mechanism study.
RESULTS
Line QR1 exhibited resistance to high quinclorac rates (up to 6400 g ha^-1), whereas line QR2 exhibited a resistance/susceptibility segregation ratio of 3:1 at the field or lower rates (400, 100 g ha^-1). Intriguingly, a lower level of ¹⁴C-quinclorac metabolism and hence a higher level of ¹⁴C-quinclorac translocation was observed in QR1 than QS plants. The basal expression levels of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) and ACC oxidase 2 (ACO2) genes did not differ significantly between the QR1 and QS lines. However, more expression of ACS and ACO genes was induced by quinclorac treatment in QS than in QR1. Basal levels of β-cyanoalanine synthase (β-CAS) gene expression were similar in QS and QR1 plants, but a greater level of down-regulation was detected in QS than in QR1 plants after quinclorac treatment.
CONCLUSION
These results indicate QR plants are less responsive to quinclorac than QS plants in terms of up-regulating quinclorac metabolism and ethylene synthesis. Resistance in this E. crus-pavonis line is likely controlled by a single major gene, involving possibly an alteration in auxin signal perception/transduction to the ethylene biosynthesis pathway. The β-CAS is unlikely to play a major role in quinclorac resistance in this particular population.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Qin Yu, Stephen B. Powles

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Echinochloa crus-pavonis (weed)	Rice (Oryza)