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Title: A beta vulgaris serine proteinase inhibitor gene (BvSTI) regulated by sugar beet root maggot feeding on moderately resistant F1016 roots

Author
item Smigocki, Anna
item Puthoff, David

Submitted to: American Society of Sugarbeet Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 10/31/2006
Publication Date: 2/26/2007
Citation: Smigocki, A.C., Puthoff, D.P. 2007. A beta vulgaris serine proteinase inhibitor gene (BvSTI) regulated by sugar beet root maggot feeding on moderately resistant F1016 roots. American Society of Sugarbeet Technologists. Proceedings, p. 67.

Interpretive Summary:

Technical Abstract: Damage from the sugar beet root maggot (SBRM) is a serious problem and control of this devastating pest ultimately relies on environmentally damaging insecticides. To explore novel strategies for management of SBRM and gain knowledge of root defense response mechanisms, we examined root gene expression incited by SBRM in a moderately resistant F1016 and a susceptible parental F1010 line. A gene of particular interest, coding for a serine (trypsin) protease inhibitor (BvSTI), was identified in the F1016 EST library. BvSTI also shares sequence similarity with a tomato gene (LeMir) that is primarily expressed in the maturing epidermis of the root, is induced by invading nematodes, and is secreted to the rhizosphere. Gene expression profiles of BvSTI revealed its regulation by exogenous methyl jasmonate but not mechanical wounding, salicylic acid or ethylene. Given serine proteases comprise the major digestive enzymes in root maggot midguts, our findings suggest that BvSTI may be involved in the resistance mechanism of F1016. To elucidate the functional role of BvSTI in insect resistance and root biology, the BvSTI coding region was fused to the CaMV 35S promoter for overexpression in sugar beet hairy root cultures. Trypsin inhibitory activity increased 2 to 4-fold in the transformed roots. Studies on the effects of the inhibitor on insect mortality and growth rates are in progress. Cloning of BvSTI suggests that the proteinase inhibitor may form a zone of protection surrounding the moderately resistant F1016 roots and act as a first line of defense in the peripheral cell layers.