A Common Genetic Basis in Sweet Corn Inbred Cr1 for Cross Sensitivity to Multiple Cytochrome P450-Metabolized Herbicides

Abstract

Nicosulfuron, mesotrione, dicamba plus diflufenzopyr, and carfentrazone are postemergence herbicides from different chemical families with different modes of action. An association between the sensitivity of sweet corn to these herbicides was observed when 143 F3 : 4families (F4plants) derived from of a cross between Cr1 (sensitive inbred) and Cr2 (tolerant inbred) were evaluated in greenhouse trials. The ratio of tolerant : segregating : sensitive families was not significantly different from a 3 : 2 : 3 ratio, which would be expected if a single gene conditioned herbicide response. Families cosegregated for responses to these herbicides. In field studies with 60 F3 : 5families in 2005 and 120 F3 : 5families in 2007, responses to these herbicides and foramsulfuron and primisulfuron were associated. Responses to bentazon in field trials were similar to the aforementioned herbicides for tolerant families, but differences were noted for families that were sensitive or segregated for responses to nicosulfuron, foramsulfuron, primisulfuron, mesotrione, dicamba plus diflufenzopyr, and carfentrazone. The gene(s) affecting herbicide sensitivity in Cr1 maps to the same region of chromosome 5S as a previously sequenced cytochrome P450 gene, where alleles previously designatednsf1andben1were associated with sensitivity to nicosulfuron and bentazon and appear to be the result of a 392–base-pair insertion mutation. This work supports the hypothesis that a single recessive gene or closely linked genes in the sweet corn inbred Cr1 condition sensitivity to multiple cytochrome P450 enzyme-metabolized herbicides.

Tembotrione detoxification in 4‐hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor‐resistant Palmer amaranth (Amaranthus palmeri S. Wats.)

“…The process is presumed to be catalyzed by cytochrome P450s, the mechanism seen in triketone corn selectivity, where it provides tembotrione with a half‐life of less than a day . The cytochrome P450 gene Nsf1/Ben1 (gene named for nicosulfuron, Nsf, and bentazon, Ben) was identified as the single major resistance locus in corn …”

Reversing resistance to tembotrione in an Amaranthus tuberculatus (var. rudis) population from Nebraska, USA with cytochrome P450 inhibitors

“…Studies have demonstrated the capacity of synergists to revert resistance . Major concerns with synergists are that these molecules may also reduce crop selectivity and may have an unintended environmental impact . Nonetheless, the organophosphate insecticide phorate (a P450 inhibitor) provided a high level of crop safety against injury by clomazone and triallate to rice seedlings .…”

Distinct Detoxification Mechanisms Confer Resistance to Mesotrione and Atrazine in a Population of Waterhemp

“…The overall number or specific P450(s) involved with mesotrione metabolism in MCR or other waterhemp populations are not yet known. However, cross resistance to other HPPD-inhibiting herbicides (Hausman et al, 2011) suggests that either a single P450 enzyme with broad substrate specificity (Nordby et al, 2008) or multiple P450s with low substrate specificity (Urlacher, 2012) may be involved with resistance in MCR, but these remain to be determined.…”