A common genetic basis in sweet corn inbred Cr1 for cross sensitivity to multiple cytochrome P450-metabolized herbicides

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 F_3:4 families (F₄ plants) 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 F _3:5 families in 2005 and 120 F_3:5 families 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 designated nsf1 and ben1 were 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.