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QUIK STATS (last updated May 03, 2021 )
NOTES ABOUT THIS BIOTYPE
Pest Manag Sci 2020; 76: 1929–1937
Evolution of resistance to HPPD-inhibiting herbicides in a wild radish population via enhanced herbicide metabolism Huan Lu, Qin Yu,* Heping Han, Mechelle J Owen and Stephen B Powles
BACKGROUND: Relatively new herbicides that target 4-hydroxyphenylpyruvate dioxygenase (HPPD) are now available for use on the world’s great grain crops (rice, wheat, corn and soybean) and for other uses. With widespread and persistent use of HPPD-inhibiting herbicides, the evolution of HPPD-inhibiting herbicide resistant weeds is inevitable. Currently, resistance to HPPD-inhibiting herbicides is known in two weed species, waterhemp and Palmer amaranth. Here, we report a HPPD-inhibiting herbicide resistant wild radish population from the Western Australia grain belt. This population was not selected with HPPD-inhibiting herbicides, rather it evolved resistance to earlier used herbicides with different modes of action and exhibits cross-resistance to HPPD-inhibiting herbicides.
RESULTS: Dose–response experiments showed the resistant (R) population exhibits 4 to 6.5-fold resistance to the HPPD-inhibiting herbicides mesotrione, tembotrione and isoxaflutole, compared to the susceptible (S) population. This resistance is not target-site based as cloning of full coding sequences of the HPPD genes from S and R plants did not reveal resistance-endowing single nucleotide polymorphisms. The HPPD gene expression levels are similar in S and R plants. In addition, no differences in [14C]-mesotrione uptake and translocation were observed in the S and R plants. However, the time required for R plants to metabolise 50% [14C]-mesotrione is 7.7-fold faster than for the S plants.
CONCLUSION: We confirm resistance to HPPD-inhibiting herbicides exists in a population of the economically damaging global weed wild radish. The resistance in this population is due to a non-target-site based enhanced rate of herbicide metabolism.
© 2019 Society of Chemical Industry Keywords: wild radish; HPPD-inhibiting herbicides; herbicide resistance; HPPD gene; enhanced metabolism
Pest Manag Sci 2020; 76: 2015–2020
Non-target-site resistance to PDS-inhibiting herbicides in a wild radish (Raphanus raphanistrum) population. Huan Lu, Qin Yu,* Heping Han, Mechelle J Owen and Stephen B Powles
BACKGROUND: Diflufenican resistance has been reported in wild radish populations since 1998, but the resistance mechanisms have not been investigated. Recently, we identified a wild radish population (H2/10) from the Western Australian grain belt that is resistant (R) to the phytoene desaturase (PDS)-inhibiting herbicide diflufenican.
RESULTS: Dose–response results showed this R population is 4.9-fold more resistant than the susceptible (S) population based on the LD50 R/S ratio. In addition, the R population also exhibits cross-resistance to the PDS-inhibiting herbicide fluridone. The cytochrome P450 inhibitor malathion reversed diflufenican resistance and partially reversed fluridone resistance in the R population. The full coding sequences of the PDS gene were cloned from the S and R plants and there are natural variations in the PDS gene transcripts/alleles with no correlation to resistance. In addition, the R plants had a level of PDS gene expression that is not significantly different from the S plants.
CONCLUSION: These results demonstrated that diflufenican resistance in this R wild radish population is likely due to non-target-site based enhanced herbicide metabolism involving cytochrome P450s.
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