Hydroxygeranyllinalool Glycosides from Tobacco Exhibit Antibiosis Activity in the Tobacco Budworm [Heliothis virescens (F.)]

Abstract

Leaves of Tobacco Introduction TI-165 were found to be resistant to tobacco budworm [Heliothis virescens (F.)] attack. HPLC profiles of leaf extracts showed that TI-165 had relatively high levels of two components (A and B) that were absent in susceptible varieties. Compounds A and B were isolated from TI-165 by a combination of preparative C18, silicic acid column, and centrifugal thin-layer chromatography. They were identified as diterpene glycosides: compound A, 16-hydroxygeranyllinalyl-3-O-[α-l-rhamnopyranosyl(1→4)]-β-d-glucopyranoside-16-O-[α-l-rhamnopyranosyl(1→6)]-β-d-glucopyranoside; compound B, 16-hydroxygeranyllinalyl-3-O-[α-l-rhamnopyranosyl(1→4)]-β-d-glucopyranoside-16-O-[α-l-rhamnopyranosyl(1→6)]-[α-l-rhamnopyranosyl(1→4)]-β-d-glucopyranoside (hydroxygeranyllinalool glycosides). Budworm bioassays with whole tobacco leaves and purified mixtures of A and B showed significant correlation between larval weights and levels of A and B. HPLC analyses of freeze-dried leaves of 68 Nicotiana species indicated that 26 species had high levels of diterpene glycosides identical to or related to A and B. Keywords: Nicotiana; Heliothis virescens (F.); antibiosis; 16-hydroxygeranyllinalool glycosides; diterpene glycosides

Jasmonate and ppHsystemin Regulate Key Malonylation Steps in the Biosynthesis of 17-Hydroxygeranyllinalool Diterpene Glycosides, an Abundant and Effective Direct Defense against Herbivores inNicotiana attenuata

“…Furthermore, we discovered that the malonyl group is easily lost to nonenzymatic cleavage in solutions with a similar pH to the lepidopteran midgut (pH 11; data not shown; Dow, 1992); thus, it is unlikely that malonylated compounds would survive in the midgut. It is unlikely that the loss of the malonyl group would result in a more toxic compound, but rather that cleavage of the sugar moieties and exposure of the geranyllinalool skeleton could be toxic (Lemaire et al, 1990;Snook et al, 1997). We propose that malonyl moieties are more likely involved in regulating within-plant transport and storage of HGL-DTGs.…”

“…Snook et al (1997) found HGL-DTGs to be highly abundant (>2.5% dry mass) in at least 26 Nicotiana species. Several studies have found negative correlations between total HGL-DTG content and the mass gained by lepidopteran larvae feeding on different species of Nicotiana (Lou and Baldwin, 2003), different cultivars of tobacco (Nicotiana tabacum) (Snook et al, 1997), or different transformed lines of the wild tobacco Nicotiana attenuata (Mitra et al, 2008). Larvae of the solanaceous specialist tobacco hornworm Manduca sexta reared on agar diets coated with isolated plant HGL-DTG fractions grew less than larvae reared on water-coated diets (Jassbi et al, 2006).…”

“…Malonyl groups are typically connected to the C'-6hydroxyl group of the glucose(s) (Taguchi et al, 2005;Yu et al, 2008). HGL-DTGs have been isolated from many members of the Solanaceae, including tobacco (Nicotiana spp) (Shinozaki et al, 1996;Snook et al, 1997;Jassbi et al, 2006), C. annuum (Izumitani et al, 1990;Hashimoto et al, 1997;Lee et al, 2006Lee et al, , 2007Lee et al, , 2008De Marino et al, 2006), and wolfberry (Lycium chinense) (Terauchi et al, 1995(Terauchi et al, , 1998. Snook et al (1997) found HGL-DTGs to be highly abundant (>2.5% dry mass) in at least 26 Nicotiana species.…”

“…HGL-DTGs have been isolated from many members of the Solanaceae, including tobacco (Nicotiana spp) (Shinozaki et al, 1996;Snook et al, 1997;Jassbi et al, 2006), C. annuum (Izumitani et al, 1990;Hashimoto et al, 1997;Lee et al, 2006Lee et al, , 2007Lee et al, , 2008De Marino et al, 2006), and wolfberry (Lycium chinense) (Terauchi et al, 1995(Terauchi et al, , 1998. Snook et al (1997) found HGL-DTGs to be highly abundant (>2.5% dry mass) in at least 26 Nicotiana species. Several studies have found negative correlations between total HGL-DTG content and the mass gained by lepidopteran larvae feeding on different species of Nicotiana (Lou and Baldwin, 2003), different cultivars of tobacco (Nicotiana tabacum) (Snook et al, 1997), or different transformed lines of the wild tobacco Nicotiana attenuata (Mitra et al, 2008).…”

“…Larvae of the solanaceous specialist tobacco hornworm Manduca sexta reared on agar diets coated with isolated plant HGL-DTG fractions grew less than larvae reared on water-coated diets (Jassbi et al, 2006). Snook et al (1997) showed that HGL-DTGs in artificial diet reduced the mass of Heliothis virescens larvae and that this required the intact double-bond structure of the HGL skeleton.…”