Evolution of resistance to HPPD‐inhibiting herbicides in a wild radish population via enhanced herbicide metabolism

Abstract

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

Metribuzin resistance via enhanced metabolism in a multiple herbicide resistant Lolium rigidum population

“…in R . raphanistrum 35 . Hence, metabolic resistance needs to be managed effectively by diverse chemical and non‐chemical methods such as herbicide mixture/rotation and harvest weed seed control, to preserve the valuable TT herbicide technology.…”

Mechanisms of evolved herbicide resistance

“…A survey of ALSresistant A. palmeri in Georgia found that more than half of the populations had no ALS target site mutations and exhibited enhanced ALS herbicide metabolism (123). Resistance to HPPD inhibitors has been reported in A. tuberculatus (124,125), A. palmeri (110,126) and recently in R. raphanistrum (127). The resistant biotypes metabolized HPPD inhibitors at a faster rate than the susceptible populations through hydroxylation reactions, indicating a P450 role in the resistance mechanism in the broadleaf species (110,127,128).…”

“…Resistance to HPPD inhibitors has been reported in A. tuberculatus (124,125), A. palmeri (110,126) and recently in R. raphanistrum (127). The resistant biotypes metabolized HPPD inhibitors at a faster rate than the susceptible populations through hydroxylation reactions, indicating a P450 role in the resistance mechanism in the broadleaf species (110,127,128). Recently, A. tuberculatus biotypes from Nebraska with resistance to tembotrione and 2,4-D, as well as A. palmeri from Arkansas with resistance to fomesafen, were controlled when a P450 inhibitor was applied (111,113,129).…”

Herbicide resistance in Amaranthus tuberculatus†

“…Resistance to HPPD inhibitors is rare in weeds, having been reported in only two other weed species after having been first reported in A. tuberculatus. 28,67 The first cases of HPPD-inhibitor www.soci.org PJ Tranel wileyonlinelibrary.com/journal/ps resistance in A. tuberculatus were observed in commercial maize seed fields. 16,27 Such production systems rely on HPPD-inhibiting herbicides (because of their crop safety across inbred lines), often are not rotated to other crops, and have high weed pressure due to poor crop competitiveness and dispersed plantinga 'perfect storm' for resistance evolution.…”