RNAi-Based Biocontrol of Wheat Nematodes Using Natural Poly-Component Biostimulants.

Konstantin B Blyuss,Galyna O Iutynska,Yaroslav B Blume,Victoria A Tsygankova,Alla I Yemets,Liudmyla O Biliavska,Farzad Fatehi

doi:10.3389/fpls.2019.00483

Konstantin B Blyuss, Galyna O Iutynska + Show 5 more

Open Access

https://doi.org/10.3389/fpls.2019.00483

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Abstract

With the growing global demands on sustainable food production, one of the biggest challenges to agriculture is associated with crop losses due to parasitic nematodes. While chemical pesticides have been quite successful in crop protection and mitigation of damage from parasites, their potential harm to humans and environment, as well as the emergence of nematode resistance, have necessitated the development of viable alternatives to chemical pesticides. One of the most promising and targeted approaches to biocontrol of parasitic nematodes in crops is that of RNA interference (RNAi). In this study we explore the possibility of using biostimulants obtained from metabolites of soil streptomycetes to protect wheat (Triticum aestivum L.) against the cereal cyst nematode Heterodera avenae by means of inducing RNAi in wheat plants. Theoretical models of uptake of organic compounds by plants, and within-plant RNAi dynamics, have provided us with useful insights regarding the choice of routes for delivery of RNAi-inducing biostimulants into plants. We then conducted in planta experiments with several streptomycete-derived biostimulants, which have demonstrated the efficiency of these biostimulants at improving plant growth and development, as well as in providing resistance against the cereal cyst nematode. Using dot blot hybridization we demonstrate that biostimulants trigger a significant increase of the production in plant cells of si/miRNA complementary with plant and nematode mRNA. Wheat germ cell-free experiments show that these si/miRNAs are indeed very effective at silencing the translation of nematode mRNA having complementary sequences, thus reducing the level of nematode infestation and improving plant resistance to nematodes. Thus, we conclude that natural biostimulants produced from metabolites of soil streptomycetes provide an effective tool for biocontrol of wheat nematode.

Highlights

One of the biggest challenges to agriculture comes from pests and parasites that cause enormous economic losses and threaten global food security
That it has been established that biostimulants do have an anti-nematode effect, we look into whether this can be attributed to wheat plants producing additional si/miRNA complementary to mRNA of infested plants that is associated with plant genes, whose expression is upregulated during the entry of nematodes into plant cells, facilitating infestation of plants with nematodes, or to nematode mRNA associated with nematode genes that control nematode life cycle, nematode housekeeping genes, nematode parasitism or effector genes that are expressed during nematode entry into plant cells (Tsygankova et al, 2012a, 2014b; Li et al, 2014; Chen et al, 2015, 2017; Xu et al, 2016; Ali et al, 2017b; Yang et al, 2017; Cui et al, 2018)
In this paper we have demonstrated the feasibility of using polycomponent biostimulants derived from metabolites of various soil streptomycetes for protecting wheat plants against the cereal cyst nematode, which is known to be one of the main wheat parasites

Summary

Introduction

One of the biggest challenges to agriculture comes from pests and parasites that cause enormous economic losses and threaten global food security. The nematodes migrate intra-cellularly (cyst nematodes) or inter-cellularly (root-knot nematode) to become sedentary in the roots and form feeding cells that support further development and reproduction (Bird and Kaloshian, 2003; Caillaud et al, 2008). These feeding cells later transform into either syncytia in the case of cyst nematodes, or multinucleate giant cells for root-knot nematodes, which subsequently result in the formation of galls and plant death after several cycles of nematode reproduction. In the case of wheat (Triticum aestivum L.), its major nematode parasites are cereal cyst nematode, primarily Heterodera avenae (Nicol et al, 2007; Peng et al, 2009), and root lesion nematode Pratylenchus (P. neglectus and P. thornei) (Vanstone et al, 1998). Smiley and Nicol (2009) and Nicol and Rivoal (2008) provide nice overviews of different species of wheat nematodes, including the discussion of their epidemiology, as well as approaches to management

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