Insect and wound induced GUS gene expression from a Beta vulgaris proteinase inhibitor gene promoter

Authors: SAVIC, JELENA - University Of Belgrade; Smigocki, Anna

Submitted to: Annual Beet Sugar Development Foundation Research Report
Publication Type: Other
Publication Acceptance Date: 4/9/2012
Publication Date: 5/2/2012
Citation: Savic, J., Smigocki, A.C. 2012. Insect and wound induced GUS gene expression from a Beta vulgaris proteinase inhibitor gene promoter. Annual Beet Sugar Development Foundation Research Report. CD version only.

Interpretive Summary: Disease and pest problems decrease sugar production from the more than 26 million tons of U.S. grown sugar beet valued at over 1.2 billion dollars annually. To better understand how plants protect themselves from insect attack, we identified sugar beet genes that respond to insect attack. One of the genes (BvSTI) was selected for further analysis to determine how the gene is turned on to produce the insect fighting product. This gene’s control switch (promoter) was isolated and fused to a different gene whose product turns plant cells blue. We showed that the switch that controls the expression of the insect resistance gene BvSTI is turned on all the time in younger plants and almost absent in mature plants. However, if the older plants are wounded or fed to insects then the gene is turned on once again and is localized primarily to the wound sites. The observed continuous production of the gene product in the younger plants followed by wound and insect inducible production in the mature plants suggests that the BvSTI gene switch (promoter) should prove useful for producing insecticidal gene products throughout the life of the plant. Scientists will use this information to develop safer approaches of insect control in plants and this will lead to an increase in yields and reduction of chemical pesticide usage.

Technical Abstract: Inducible gene promoters that are specifically activated by pathogen invasion or insect pest attack are needed for effective expression of resistance genes to control plant diseases. In the present study, a promoter from a serine proteinase inhibitor gene (BvSTI) shown to be up-regulated in resistant interactions with an insect pest of sugar beet, the sugar beet root maggot, was fused to the ß-glucuronidase (GUS) reporter gene to characterize its expression patterns in transgenic plants. In transformed N. benthamiana, GUS expression was constitutive in younger plants (2 and 6 week old) and significantly reduced or absent in 3 month old plants. However, in the older plants, GUS expression was induced by physical wounding and fall armyworm feeding and was shown to be localized primarily to the wound sites. The observed constitutive expression pattern in the younger plants followed by wound and insect inducible expression in the mature plants suggests that the BvSTI promoter should prove useful for production of resistance gene products to target insect pests throughout the life of the plant.