Multiple Metabolic Enzymes Can Be Involved in Cross-Resistance to 4-Hydroxyphenylpyruvate-Dioxygenase-Inhibiting Herbicides in Wild Radish

Abstract

A wild radish population (R) has been recently confirmed to be cross-resistant to 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicides without previous exposure to these herbicides. This cross-resistance is endowed by enhanced metabolism. Our study identified one 2-oxoglutarate/Fe(II)-dependent dioxygenase gene (Rr2ODD1) and two P450 genes (RrCYP704C1 and RrCYP709B1), which were significantly more highly expressed in R versus susceptible (S) plants. Gene functional characterization using Arabidopsis transformation showed that overexpression of RrCYP709B1 conferred a modest level of resistance to mesotrione. Ultra-performance liquid chromatography–tandem mass spectrometry analysis showed that tissue mesotrione levels in RrCYP709B1 transgenic Arabidopsis plants were significantly lower than that in the wild type. In addition, overexpression of Rr2ODD1 or RrCYP704C1 in Arabidopsis endowed resistance to tembotrione and isoxaflutole. Structural modeling indicated that mesotrione can bind to CYP709B1 and be easily hydroxylated to form 4-OH-mesotrione. Although each gene confers a modest level of resistance, overexpression of the multiple herbicide-metabolizing genes could contribute to HPPD-inhibiting herbicide resistance in this wild radish population.

Metabolism of the 4-Hydroxyphenylpyruvate Dioxygenase Inhibitor, Mesotrione, in Multiple-Herbicide-Resistant Palmer amaranth (Amaranthus palmeri)

“…These MHR populations produced qualitatively similar mesotrione metabolites as MHR waterhemp (SIR), which implies a similar class (or classes) of detoxification enzymes is responsible for resistance. Increased relative abundance of 5-OH-mesotrione in Palmer amaranth compared to waterhemp indicates a different detoxification mechanism in Palmer amaranth; however, given the multigenic nature of HPPD-inhibitor resistance ,, and recent reports on roles of other genes/enzymes in mesotrione resistance, ,, a combination of P450s, other (non-P450) oxygenases, and/or GSTs could possibly confer resistance to HPPD-inhibiting herbicides in weedy amaranths.…”

“…The HIS1 gene also conferred resistance to mesotrione in transgenic soybean . Furthermore, in wild radish (Raphanus raphanistrum), a 2-oxoglutarate/Fe­(II)-dependent dioxygenase ( Rr2ODD1 ), in addition to two P450 genes, confers resistance to HPPD-inhibiting herbicides mesotrione, tembotrione and isoxaflutole …”

“…These phases sequentially modify herbicides into nonphytotoxic forms via the action of various detoxification enzymes . Metabolic resistance via Phase I ring hydroxylation of parent mesotrione is the main reported mechanism for mesotrione among weedy Amaranthus species and has largely been associated with cytochrome P450-dependent monooxygenases (P450s) and other potential detoxification enzymes in other dicots . P450s form a large family of enzymes essential for the metabolism of toxins of foreign origin (xenobiotics), such as herbicides. , In 2009, a population of waterhemp (A.…”

First Report on Resistance to HPPD Herbicides Mediated by Nontarget-Site Mechanisms in the Grass Leptochloa chinensis

“…Similarly, there have been two reported cases of HPPD-resistant Palmer amaranth in Kansas and Nebraska. The former involved no history of HPPD use but had a long history of PS II (photosystem II) and ALS herbicide use, while the latter involved a history of HPPD use. , The resistance mechanisms of the above two weeds appear to belong to nontarget resistance. ,, The third case, in wild radish, occurred in Australia and involved no history of HPPD use, and the resistance observed in this population was due to a nontarget-site-based mechanism associated with one 2-oxoglutarate/Fe­(II)-dependent dioxygenase gene ( Rr2ODD1 ) and two P450 genes ( RrCYP704C1 and RrCYP709B1 ). , The fourth example concerned redroot pigweed, and information on resistance, including the history of herbicide use at the site of discovery, is currently unavailable . This study reports the fifth HPPD-resistant weed.…”

“…All but one of the reports of resistant Palmer amaranth is related to enhanced herbicide metabolism; in the sole exception, reported by Shyam in 2021, the mechanism of resistance to mesotrione and tembotrione in Kansas was unclear . In resistant wild radish populations, metabolic resistance mechanisms involving two gene families, the P450 family and dioxygenase family genes, have been suggested. − In the newly reported resistant redroot pigweed populations, the mechanism of resistance is also not yet clear . Significantly, scholars have identified the HPPD INHIBITOR SENSITIVE 1 ( HIS1 ) gene as a regulator of the responsiveness of rice to the HPPD inhibitor BBC (benzobicyclon).…”