Abstract
The polyphagous insect-pest, Helicoverpa armigera, is a serious threat to a number of economically important crops. Chemical application and/or cultivation of Bt transgenic crops are the two strategies available now for insect-pest management. However, environmental pollution and long-term sustainability are major concerns against these two options. RNAi is now considered as a promising technology to complement Bt to tackle insect-pests menace. In this study, we report host-delivered silencing of HaAce1 gene, encoding the predominant isoform of H. armigera acetylcholinesterase, by an artificial microRNA, HaAce1-amiR1. Arabidopsis pre-miRNA164b was modified by replacing miR164b/miR164b* sequences with HaAce1-amiR1/HaAce1-amiR1* sequences. The recombinant HaAce1-preamiRNA1 was put under the control of CaMV 35S promoter and NOS terminator of plant binary vector pBI121, and the resultant vector cassette was used for tobacco transformation. Two transgenic tobacco lines expressing HaAce1-amiR1 was used for detached leaf insect feeding bioassays. Larval mortality of 25% and adult deformity of 20% were observed in transgenic treated insect group over that control tobacco treated insect group. The reduction in the steady-state level of HaAce1 mRNA was 70–80% in the defective adults compared to control. Our results demonstrate promise for host-delivered amiRNA-mediated silencing of HaAce1 gene for H. armigera management.
Highlights
World population is likely to reach nine billion by 2050 [1]
HD-Artificial microRNA (amiRNA) mediated silencing of H. armigera HaAce1 gene important crops like chickpea, pigeonpea, sorghum, soybean, and cotton, causing serious damage to crop yield [3]
HD-amiRNA mediated silencing of H. armigera HaAce1 gene against H. armigera had been reported by host-delivered hpRNAi-mediated silencing of EcR, HR3, AK, CHI and NPF genes [26,27,28,29,30]
Summary
World population is likely to reach nine billion by 2050 [1]. Feeding such a huge population with declining cultivable land area is a herculean task for the entire agricultural community. In such a scenario, harnessing entire genetic potential of the crop with minimum ecological disturbance is a new slogan for increasing agricultural production. Insect-pests infestations severely limit the productivity of crops. Food plants are damaged by more than 10,000 species of insects, leading to yield loss as high as 60–70% [2]. Helicoverpa armigera, a notorious polyphagous insect, feeds on a wide variety of agriculturally
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