Abstract
BackgroundSpodoptera litura (Lepidoptera: Noctuidae), commonly known as tobacco cutworm or cotton leafworm, is a polyphagous pest which causes considerable damage to cotton (Gossypium hirsutum) and other crops. Herbivore-induced defence response is activated in plants against chewing pests, in which plant secondary metabolites play an important role. Dhurrinase2 (SbDhr2), a cyanogenic β-glucosidase from Sorghum bicolor, is the key enzyme responsible for the hydrolysis of dhurrin (cyanogenic β-glucosidic substrate) to p-hydroxymandelonitrile. Hydroxynitrile lyase (MeHNL) from Mannihot esculanta catalyses the dissociation of cyanohydrins to hydrogen cyanide and corresponding carbonyl compound, both enzymes play a pivotal role in plant defence mechanism.ResultsSbDhr2 and MeHNL genes were expressed individually and co-expressed transiently in cotton leaves. We examined the feeding response of S. litura to leaves in the choice assay. The S. litura population used in this study showed better feeding deterrence to leaves co-expressing both genes compared with the expression of an individual gene.ConclusionOur results suggest that co-expression of SbDhr2 and MeHNL genes in cotton leaves demonstrate feeding deterrence to S. litura. Engineering cyanogenic pathway in aerial parts of cotton would be an additional defence strategy against generalist pests and can be enhanced against specialist pests.
Highlights
Spodoptera litura (Lepidoptera: Noctuidae), commonly known as tobacco cutworm or cotton leafworm, is a polyphagous pest which causes considerable damage to cotton (Gossypium hirsutum) and other crops
This paper investigates feeding deterrence and settling preference choice assay with S. litura on cotton leaves, transiently expressing SbDhr2 and Mannihot esculanta α-hydroxynitrile lyase (MeHNL) genes, the former driven by phosphoenolpyruvate carboxylase (PEPC) and the latter by 2X CaMV 35S promoter (Pauli et al 2004)
Screening of genes and expression in non-infiltrated cotton leaves polymerase chain reaction (PCR) analysis confirmed the presence of MeHNL (Fig. 6a) and SbDhr2 genes (Fig. 6b)
Summary
Spodoptera litura (Lepidoptera: Noctuidae), commonly known as tobacco cutworm or cotton leafworm, is a polyphagous pest which causes considerable damage to cotton (Gossypium hirsutum) and other crops. Herbivore-induced defence response is activated in plants against chewing pests, in which plant secondary metabolites play an important role. Spodoptera litura (Lepidoptera: Noctuidae) commonly known as tobacco cutworm or cotton (Cheng et al 2017) leafworm is a polyphagous pest, causes considerable damage to cotton (Gossypium hirsutum) and various other crops (Xue et al 2010; Bragard et al 2019). Metabolic engineering of the whole cyanogenic pathway in different plants has been reported for insect herbivory deterrence (Franks et al 2006; Blomstedt et al 2016; Tattersall et al 2001; Bak et al 2000)
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