Sugar beet proteinase inhibitor (BvSTI) gene promoter is regulated by insects and wounding in transgenic Nicotiana.
A regulatory sequence from a serine proteinase inhibitor gene (BvSTIpro) that is induced by the sugar beet root maggot was fused to the β-glucuronidase (GUS) reporter gene to characterize its expression patterns in transgenic Nicotiana benthamiana plants. In 2- and 6-week old BvSTIpro-GUS transformed plants, GUS expression was observed throughout leaves and roots that was comparable to GUS staining detected in plants transformed with the positive control 35S-GUS gene construct. At 10-14 weeks, GUS expression in the leaves and roots was reduced as compared to the younger plants and the 35S-GUS control but was up-regulated by abiotic and biotic stress. At 6 to 24 hours after mechanical wounding, GUS expression increased throughout the wounded leaves and roots of 14-week old plants to constitutive levels observed with the 35S-GUS gene. Fall armyworm (Spodoptera frugiperda) feeding on BvSTIpro-GUS leaves and roots similarly induced GUS gene activity like those observed with the 35S-GUS control. We demonstrate that the BvSTI promoter induced gene expression in response to abiotic and biotic stresses. Fusion of the BvSTI promoter to resistance genes should provide expression at sites of pest and pathogen invasion to augment the capacity of the plant to defend itself.