Host-derived gene silencing of parasite fitness genes improves resistance to soybean cyst nematodes in stable transgenic soybean

Abstract

Key message Soybean expressing small interfering RNA of SCN improved plant resistance to SCN consistently, and small RNA-seq analysis revealed a threshold of siRNA expression required for resistance ability. Abstract Soybean cyst nematode (SCN), Heterodera glycines , is one of the most destructive pests limiting soybean production worldwide, with estimated losses of $1 billion dollars annually in the USA alone. RNA interference (RNAi) has become a powerful tool for silencing gene expression. We report here that the expression of hairpin RNAi constructs, derived from two SCN genes related to reproduction and fitness, HgY25 and HgPrp17, enhances resistance to SCN in stably transformed soybean plants. The analyses of T 3 to T 5 generations of stable transgenic soybeans by molecular strategies and next-generation sequencing confirmed the presence of specific short interfering RNAs complementary to the target SCN genes. Bioassays performed on transgenic soybean lines targeting SCN HgY25 and HgPrp17 fitness genes showed significant reductions (up to 73%) for eggs/g root in the T 3 and T 4 homozygous transgenic lines. Targeted mRNAs of SCN eggs collected from the transgenic soybean lines were efficiently down-regulated, as confirmed by quantitative RT-PCR. Based on the small RNA-seq data and bioassays, it is our hypothesis that a threshold of small interfering RNA molecules is required to significantly reduce SCN populations feeding on the host plants. Our results demonstrated that host-derived gene silencing of essential SCN fitness genes could be an effective strategy for enhancing resistance in crop plants. Electronic supplementary material The online version of this article (10.1007/s00122-019-03379-0) contains supplementary material, which is available to authorized users.

Cyst nematode bio‐communication with plants: implications for novel management approaches

“…Host‐induced gene silencing has become the most commonly applied method to develop synthetic resistance to plant parasitic nematodes. A rapid screening approach was developed exploiting Agrobacterium rhizogenes hairy root transformation and the gateway cloning system for rapid screening of candidate genes, 85–87 and various plant parasitic nematode genes involved in essential cellular functions have been used to achieve varying degrees of transient resistance 85,88–91 . Genes providing plant parasitic nematode resistance in these screens are then amenable to generation of stable transformed plants through conventional means.…”

“…A rapid screening approach was developed exploiting Agrobacterium rhizogenes hairy root transformation and the gateway cloning system for rapid screening of candidate genes, [85][86][87] and various plant parasitic nematode genes involved in essential cellular functions have been used to achieve varying degrees of transient resistance. 85,[88][89][90][91] Genes providing plant parasitic nematode resistance in these screens are then amenable to generation of stable transformed plants through conventional means. The advent of technologies like gene stacking makes it possible to enhance host-induced gene silencing approaches to plant-parasitic nematodes.…”

RNA Interference and CRISPR/Cas Gene Editing for Crop Improvement: Paradigm Shift Towards Sustainable Agriculture

“…No complete resistance was, however, observed but the reduction in developing nematodes ranges from 23-64% in different RNAi lines (Sindhu et al 2009). Similarly, enhanced resistance against soybean cyst nematode Heterodera glycines has been reported by targeting reproduction and fitness-related genes; i.e., HgY25 and HgPrp17 in soybean transgenic lines (Tian et al 2019).…”

Plant miRNA Cross-Kingdom Transfer Targeting Parasitic and Mutualistic Organisms as a Tool to Advance Modern Agriculture

“…Most of the scientific literature on gene silencing mechanisms comes from nematodes, specifically from Caenorabditis elegans. However, these studies mostly focus on the ability to uptake double strand RNAs (dsRNAs) from the environment (Huang et al, 2006;Tian et al, 2019) rather than on the cross-kingdom transfer of plant miRNAs. Many studies have investigated the involvement of plant miRNAs and their corresponded gene targets in response to phytonematodes infection (Hewezi et al, 2008;Li et al, 2012;Lei et al, 2019;Pan et al, 2019).…”