Distribution and antifeedant associations of sesquiterpene lactones in cultivated sunflower (Helianthus annuus L.) on western corn rootworm (Diabrotica virgifera virgifera LeConte)

Abstract

Seven antifeedant sesquiterpene lactones (STLs), 4,5-dihydroniveusin A, argophyllin B, argophyllin A, 15-hydroxy-3-dehydrodesoxytifruticin, niveusin B, 1,2-anhydridoniveusin A, and an unidentified epoxide, in cultivated sunflower (Helianthus annuus L.) have been quantified by a highperformance thin-layer chromatography and UV-reflectance scanning densitometry analysis. Age-related expression of STL content in sunflower reveals a heretofore undescribed pattern in which nonpolar STLs such as 15-hydroxy-3-dehydrodesoxytifruticin predominate up to an age of three weeks, but are subsequently displaced by polar STLs, especially argophyllin A, through later foliar stages and anthesis. This leaf pattern of STL ontogeny is maintained in three widely differentH. annuus cultivars (Giant Gray Stripe, Royal Hybrid 2141, Hybrid 7111), which in turn had similar total contents of STLs. Antifeedant activity for western corn rootworm was positively correlated with STL content, particularly with argophyllin A and its isomer argophyllin B, in respective tissue extracts. Enhanced amounts of highly antifeedant argophyllins, especially in newly grown leaf and floral tissues yielding sunflower progeny, strongly suggest that these epoxy-STLs are a chemical defense against insect herbivory.

Refined molecular and crystal structure of silk I based on Ala-Gly and (Ala-Gly)2?Ser-Gly peptide sequence

“…It is well known that the α,β‐unsaturated carbonyl groups can act as an alkylating agents toward biological molecules 3, 32–35. Taking into account that germacrone ( 11 ) is the most important component in B salicifolia essential oil, the biological activities showed by this compound and the related sesquiterpenes 12, 13 and 14 were investigated.…”

The identification of potential aeroallergen/irritant(s) from oilseed rape (Brassica napus spp. oleifera): volatile organic compounds emitted during flowering progression

“…Public exposure to other compounds (organic sulphides and glucosinolate breakdown products) could also be expected to be widespread due to their release during food preparation of cabbage and related species ofcruciferae [10,11,20]. This does not, however, exclude the distinct possibility that individual compounds within these chemical groups might be more potent respiratory irritants, especially since many plant volatiles have evolved as feedant deterrent against insect and herbivore attack and as defences against fungal or bacterial infection [17,21,22].…”

Biosynthesis of Sesquiterpene Lactones in Pyrethrum (Tanacetum cinerariifolium)

“…Computational modeling showed that the atomic distance between the hydroxyl oxygen and the carbonyl carbon that forms the C-O bond in the lactonization is 0.87 Å longer in 8β-OH-GAA than in 6α-OH-GAA. This longer atomic distance excludes spontaneous lactonization, suggesting that an enzyme must be involved in the formation of the C7–C8 cis -type sesquiterpene lactones as occurring in sunflower (C7–C8 cis STLs) [20], [21].…”