The presence of jasmonate-inducible lectin genes in some but not all Nicotiana species explains a marked intragenus difference in plant responses to hormone treatment.

Tobacco (Nicotiana tabacum L. cv Samsun NN) leaves accumulate a cytoplasmic/nuclear lectin, called Nictaba, in response to methyl jasmonate. To check whether, and if so to what extent, the specific induction of this lectin applies to related species, a collection of 19 Nicotiana species--covering 12 Nicotiana sections and eight Nicotiana tabacum cultivars--was screened for their capability to synthesize the jasmonate-inducible lectin. Protein analyses by agglutination assays and western blot confirmed that only nine out of the 19 species examined synthesize lectin after jasmonate treatment. Remarkably, all allotetraploid cultivars of the N. tabacum L. species tested express the lectin after jasmonate treatment. PCR analyses demonstrated that all responsive species possess one or more lectin genes, whereas no lectin gene(s) could be traced in the non-responding species. The number of introns present in the lectin genes varies between zero and two. Four tobacco species/cultivars contain both intronless Nictaba genes as well as lectin genes with introns. These findings provide the first firm evidence for a striking intragenus difference with respect to the activation of a well-defined jasmonate-inducible gene that can be correlated with the presence/absence of orthologous genes in the genomes of closely related species from a single plant genus. In addition, the differential response of closely related tobacco species illustrates that in the field of plant hormone research, care must be taken when extrapolating results obtained with a particular model system to other--even taxonomically closely related--species.