Expression of δ-endotoxin Cry1EC from an inducible promoter confers insect protection in peanut (Arachis hypogaea L.) plants.
BACKGROUND
Spodoptera litura (F.) is a polyphagous foliage insect and a major pest on peanut (Arachis hypogaea L.). Constitutive expression of δ-endotoxin Cry1EC gives protection against S. litura, as reported earlier. In this study, insect bites and salicylic acid induced high-level expression of Cry1EC was achieved in peanut. In order to achieve this, the expression of pathogenesis responsive promoter PR-1a was enhanced by placing it downstream of the CaMV35S promoter in the pCAMBIA 1300 backbone. The resultant promoter CaMV35S(r)PR-1a expressed a high level of insecticidal δ-endotoxin Cry1EC. The Gus expression under the control of CaMV35S(r)PR-1a served as a convenient marker for evaluation of promoter response to different treatments.


RESULTS
Transgenic events that showed a very low level of uninduced expression and no expression in seeds were selected. The Cry1EC expression in leaves increased nearly eightfold in the selected event, following induction by salicylic acid. Both the salicylic-acid-treated and the S. litura-bitten leaves showed the highest expression after 2 days. Leaves from salicylic-acid-induced transgenic plants caused 100% mortality of S. litura at all stages of larval development.


CONCLUSIONS
The results suggest that high expression of inducible promoters provides a good strategy for the development of safer transgenic food and feed crops.
Tiwari
Siddharth
S
National Agri-Food Biotechnology Institute, Department of Biotechnology, Govt of India, Mohali, Punjab, India.
Mishra
Devesh K
DK
Chandrasekhar
Krishnappa
K
Singh
Pradhyumna K
PK
Tuli
Rakesh
R
D000818:Animals; D010367:Arachis / Q000235:genetics / Q000276:immunology* / Q000469:parasitology; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D004731:Endotoxins / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D006460:Hemolysin Proteins / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D007300:Insect Control / Q000379:methods*; D010935:Plant Diseases / Q000276:immunology* / Q000469:parasitology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000276:immunology* / Q000469:parasitology; D011401:Promoter Regions, Genetic; D018411:Spodoptera / Q000187:drug effects* / Q000502:physiology
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis