Abstract
The soybean cyst nematode (SCN), Heterodera glycines, is one of the most important pests limiting soybean production worldwide. Novel approaches to managing this pest have focused on gene silencing of target nematode sequences using RNA interference (RNAi). With the discovery of endogenous microRNAs as a mode of gene regulation in plants, artificial microRNA (amiRNA) methods have become an alternative method for gene silencing, with the advantage that they can lead to more specific silencing of target genes than traditional RNAi vectors. To explore the application of amiRNAs for improving soybean resistance to SCN, three nematode genes (designated as J15, J20, and J23) were targeted using amiRNA vectors. The transgenic soybean hairy roots, transformed independently with these three amiRNA vectors, showed significant reductions in SCN population densities in bioassays. Expression of the targeted genes within SCN eggs were downregulated in populations feeding on transgenic hairy roots. Our results provide evidence that host-derived amiRNA methods have great potential to improve soybean resistance to SCN. This approach should also limit undesirable phenotypes associated with off-target effects, which is an important consideration for commercialization of transgenic crops.
Highlights
The soybean cyst nematode (SCN), Heterodera glycines, is one of the most economically devastating pathogens on soybean
Three H. glycines genes encoding proteins with essential functions, designated as J15, J20, and J23, were selected as the artificial microRNA (amiRNA) targets for this study based on RNA interference (RNAi) phenotype data derived from
C. elegans actin-related protein 3 (NM_058665.4). arx-1 is an essential gene of C. elegans, as its inhibition results in embryogenesis disruption and reduced egg production [34]
Summary
The soybean cyst nematode (SCN), Heterodera glycines, is one of the most economically devastating pathogens on soybean. It is estimated that this disease causes more than one billion dollars in yield losses annually in the United States alone [1]. Current management strategies for H. glycines suffer from several limitations. Chemical nematicides often exhibit nontarget effects and increased production costs, while the effectiveness of crop rotation is limited by the dormancy of H. glycines eggs within the cysts, which can span many years [2]. Resistant cultivars have historically represented the best option for SCN management, but overreliance on a single resistance source (PI 88788) in cultivar development in the United States has led to concerns about intensive selection for virulence in nematode populations [3,4].
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