Gene cloning, recombinant expression, and bioassay of an allatotropin in Spodoptera litura Fabricius (Lepidoptera: Noctuidae)

• Published in: Journal of basic & applied zoology Vol. 82; no. 1; pp. 1 - 10
• Main Authors: Mamtha, R., Kiran, Tannavi, Chaitra, B. S., Saraswathi, Saraswathi, Sowrabha, R., Rao, Karthik V., Manjulakumari, D.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 02-10-2021; Springer Nature B.V; SpringerOpen
• Subjects: Allatotropin; Biomedical and Life Sciences; Corpora allata; Egg laying; Entomology; Females; Glutamic acid; Hydrophobicity; Invertebrates; Juvenile hormone; Juvenile hormones; Life Sciences; Molecular weight; Nickel; Nighttime; Pest control; Pests; Prokaryotic expression; Proteins; Spodoptera litura; Vitellogenesis; Zoology; Prokaryotic expression; Egg-laying; Allatotropin; Juvenile hormone
• ISSN: 2090-990X; 2090-990X
• DOI: 10.1186/s41936-021-00242-x

Background
Allatotropin, a neuropeptide found in several invertebrates indirectly regulates vitellogenesis by stimulating juvenile hormone biosynthesis by the corpora allata. Here, we cloned and expressed the gene encoding allatotropin of
Spodoptera litura
(tobacco cutworm), a polyphagous pest in the Asian tropics. This study is aimed at studying the effect of recombinant protein on egg-laying in females of
S. litura
as it could be used as a method to control the pests from a reproductive perspective.
Results
The protein encodes a full-length open reading frame consisting of 173 amino acids and was rich in arginine (10%) and glutamic acid (9.3%). The theoretical pI of the protein was 5.47 and a hydrophobic signal peptide of 22 residues was predicted. The recombinant allatotropin was expressed in
Escherichia coli
BL21 (DE
3
) and purified by nickel exchange chromatography. The molecular weight of the recombinant protein was about 37 kDa and expression levels up to 5.3 mg/ml were achieved. Injection assay in vitro indicated that allatotropin induces egg-laying during the first scotophase after treatment in females of
Spodoptera litura
.
Conclusion
Allatotropin induces egg-laying in female moths and could be a potential molecule for the development of control strategies against
Spodoptera litura
. In this strategy, the protein if delivered to the females before mating may lead to accelerated egg deposition much before she encounters the male moths, thus the population being checked as the eggs deposited by the females are unfertilized. Thus, the present work could lead to the development of a protein based biopesticide resulting into a species-specific and an eco-friendly way of pest control.