Figure 4.

Seven ERF Genes Are Clustered at the NIC2 Locus.

(A) Cosegregation of ERF genes. A genetic cross between nic1 and nic1 nic2 produced a population of tobacco F2 plants (n = 114) in which deletions of ERF genes found in nic2 segregated in the nic1 background. The presence or absence of ERF genes was analyzed by genomic PCR. Arrowheads indicate individual F2 plants in which homozygous deletions of ERF genes (erf/erf) were observed. ERF199 was analyzed as a control for nondeleted ERF genes.

(B) The low-nicotine phenotype of the nic2 mutation is genetically linked with the ERF deletion. The F2 plants analyzed in (A) (n = 114) were used to determine nicotine levels in the leaves. The plants in which the seven ERF genes were not detected (erf/erf; n = 28) are indicated with black bars, while the plants in which these ERF genes were present (ERF/ERF or ERF/erf; n = 86) are shown with gray bars. DW, dry weight.