Abstract
RNA
interference (RNAi) has been developed as a powerful technique in the research
of functional genomics as well as plant pest control. In this report,
double-stranded RNAs (dsRNA) targeting 3-hydroxy-3-methylglutaryl coenzyme A
reductase (HMGR) gene, which catalyze a rate-limiting enzymatic reaction in the
mevalonate pathway of juvenile hormone (JH) synthesis in cotton bollworm, was
expressed in cotton plants via Agrobacterium tumefaciens-mediated
transformation. PCR and Sothern analysis revealed the integration of HMGR gene
into cotton genome. RT-PCR and qRT-PCR confirmed the high transcription level
of dsHMGR in transgenic cotton lines. The HMGR expression both in transcription
and translation level was significantly downregulated in cotton bollworms
(helicoverpa armigera) larvae after feeding on the leaves of HMGR transgenic
plants. The transcription level of HMGR gene in larvae reared on transgenic
cotton leaves was as much as 80.68% lower than that of wild type. In addition,
the relative expression level of vitellogenin (Vg, crucial source of
nourishment for offspring embryo development) gene was also reduced by 76.86% when
the insect larvae were fed with transgenic leaves. The result of insect
bioassays showed that the transgenic plant harboring dsHMGR not only inhibited
net weight gain but also delayed the growth of cotton bollworm larvae. Taken
together, transgenic cotton plant expressing dsRNAs successfully downregulated
HMGR gene and impaired the development and survival of target insect, which
provided more option for plant pest control.
http://www.ijbs.com/v11p1296