Expression and subcellular compartmentation of Aspergillus niger b-glucosidase in transgenic tobacco result in an increased insecticidal activity on whiteflies (Bemisia tabaci) Shu Wei 1 , Yaniv Semel, Ben-Ami Bravdo, Henryk Czosnek, Oded Shoseyov * The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture and The Otto Warburg Minerva Center for Agricultural Biotechnology, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel Received 24 August 2006; received in revised form 16 November 2006; accepted 28 February 2007 Available online 12 March 2007 Abstract Transgenic Nicotiana tabacum plants expressing Aspergillus niger b-glucosidase (EC 3.2.1.21) gene (BGL1) in different subcellular compartments [cell wall (Tcw), endoplasmic reticulum (Ter), and vacuole (Tvc)] were analyzed to study the effects of BGL1 localization on plant growth and plant–insect interaction. Transgenic and non-transgenic plants were grown and characterized in a greenhouse with 25/16 8C day/ night temperatures and natural sunlight. Plant insecticidal activity was analyzed with adult whiteflies (Bemisia tabaci) in vial and cage experiments. Compared with wild-type controls, Ter and Tvc transgenic plants did not differ significantly in seed germination, plant growth rate, plant height, or flowering time. However, in Tcw seed germination and beginning of flowering were significantly delayed, and leaf area and plant fresh weight were significantly reduced. Transgenic plants had a marked insecticidal effect on whiteflies (Bemisia tabaci) and on Diptera spp. flies. The density of secretory glandular trichomes was significantly greater in transgenic than in wild-type leaves. This work indicates that hydrolysis of yet to be identified glycosides, may play an important role in plant insect resistance mechanism and plant trichome development. # 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Bemisia tabaci; b-Glucosidase; Nicotiana tabacum; Plant–insect interactions; Trichome 1. Introduction Plants have developed a number of strategies to defend themselves from herbivore attack. Morphologically specialized structures such as trichomes, spines, and waxes located in plant surface may serve as physical barriers to prevent herbivore feeding; an array of chemicals plants produce may deter herbivores or retard their growth, and/or compounds (volatile signals) that attract herbivore predators [1,2]. Many defense chemicals are stored as b-glucosides in plants so that these toxic aglycones are converted into non-toxic and inactive forms [3]. b-Glycosidase (b-glucoside glucohydrolases, EC 3.2.1.21), which hydrolyzes a broad range of aryl- and alkyl- b-D-glucosides, as well as glucosides with only a carbohydrate moiety, has been found as an elicitor of herbivore-induced plant volatiles that attract herbivore predators [4]. Stotz et al. showed that chewing insects and specific treatments (e.g., jasmonic acid) induce b-glucosidase genes in Arabidopsis thaliana [5]. In a recent study of the transcriptional profile of A. thaliana during systemic acquired resistance (SAR), Maleck et al. showed that transcription of the b-glucosidase gene psr3.1 was elevated nearly eight-fold within 48 h after infection with the oomycete Peronospora parasitica [6]. Among the genes induced by whiteflies (Bemisia tabaci), enhanced local expression of the b-glucosidase gene was also found in squash plants infested with tobacco whitefly [7]. In plants, b-glucosidase activity is spatially and devel- opmentally regulated. A compartmentation of substrate and enzyme at the tissue or subcellular level has been demonstrated in the cases of cyanogenic glucosides and their metabolizing b- glucosidases [8,9], and with glucosides of herbivore toxins such as hydroxymates and their relevant glucosidase [10,11]. A. niger b-glucosidase is active at low pH values and effectively hydrolyzes a wide range of substrates such as the glucosides of www.elsevier.com/locate/plantsci Plant Science 172 (2007) 1175–1181 * Corresponding author. Tel.: +972 8 9489084; fax: +972 8 9462283. E-mail addresses: weishu@agr.gc.ca (S. Wei), shoseyov@agri.huji.ac.il (O. Shoseyov). 1 Present address: Saskatoon Research Center, Agriculture and Agri-Food Canada, 107 Science Place, Sask. S7N 0X2, Canada. 0168-9452/$ – see front matter # 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.plantsci.2007.02.018