Abstract
Plant endoparasitic cyst nematode Heterodera schachtii Schmidt, gallic nematode Meloidogyne incognita and stem nematode Ditylenchus destructor damage various agricultural crops. The application of ecologically safe natural biostimulants with bioprotective properties is a newer approach for increasing plant resistance to parasitic nematodes. The molecular-genetic analysis of biostimulants action on plant genome is necessary for creation of new effective bioregulators for plant protection against phytopathogenic organisms. In our field and greenhouse experiments, we investigated the influence of new natural biostimulants Avercom and its derivatives on plant protection against nematodes Meloidogyne incognita and Ditylenchus destructor. Considerable increase of resistance to nematodes and productivity of cucumber and potato were observed for plants treated by biostimulant Avercom and its derivatives. Impact of biostimulants Radostim-super and Avercom on increase of resistance of sugar beet and cucumber sprouts to nematodes Heterodera schachtii and Meloidogyne incognita was studied in the laboratory conditions. Comparative analysis of morpho-physiological signs of control and experimental plants showed that plants treated by Radostim-super and Avercom were more viable and resistant to these nematodes as compared to control sprouts. In the molecular-genetic experiments, we studied the impact of these biostimulants on inducing synthesis of small regulatory si/miRNA, which plays key role in plant immune protection. Using method Dot-blot hybridization we studied degree of homology between si/miRNA with mRNA populations, isolated from plants untreated and treated with new natural biostimulants. We found considerable difference in the degree of homology (6-28%) between populations of mRNA and si/miRNA from nematode-infected plants that were either untreated or treated with biostimulants. We have also investigated silencing of translation of mRNA activity of si/miRNA in the wheat embryo cell-free system of protein synthesis. In these experiments, we found high inhibitory activity (38-65%) of si/miRNA from plants treated by biostimulants as compared to low inhibitory activity (15-20%) of si/miRNA from untreated plants. Obtained differences in the degree of homology between populations of mRNA and si/miRNA from untreated and treated with biostimulants plants, which were infected by nematode, and also the high inhibitory activity of si/miRNA from plants treated by biostimulants confirm that these biostimulants induce synthesis of anti-nematodic si/miRNA in plants, resulting in considerable increase of their resistance to these phytopathogens.
Highlights
IntroductionOver the last ten years a key role of short interfering RNA (siRNA) and microRNA (miRNA) in the TGS and PTGS - the basic processes of plant development and adaptation to stress-factors of environment, is disclosed (Angaji et al, 2010; Chen, 2009; Filipowicz et al, 2005; Hamilton et al, 2002; Luna et al, 2012; Mirouze et al, 2011; Park et al, 2002; Rasmann et al, 2012; Vaucheret et al, 2001; Zhang et al, 2007)
Obtained differences in the degree of homology between populations of mRNA and si/miRNA from untreated and treated with biostimulants plants, which were infected by nematode, and the high inhibitory activity of si/miRNA from plants treated by biostimulants confirm that these biostimulants induce synthesis of anti-nematodic si/miRNA in plants, resulting in considerable increase of their resistance to these phytopathogens
It was found that in the field, greenhouse and laboratory experiments according to morpho-physiological signs of plants the application of new natural biostimulants: Radostim-super, Avercom and its derivates leads to considerable increase of resistance of sugar beet, cucumber and potato plants to nematodes H. schachtii, M. incognita and D. destructor
Summary
Over the last ten years a key role of short interfering RNA (siRNA) and microRNA (miRNA) in the TGS and PTGS - the basic processes of plant development and adaptation to stress-factors of environment, is disclosed (Angaji et al, 2010; Chen, 2009; Filipowicz et al, 2005; Hamilton et al, 2002; Luna et al, 2012; Mirouze et al, 2011; Park et al, 2002; Rasmann et al, 2012; Vaucheret et al, 2001; Zhang et al, 2007). In a process of PTGS called RNA interference (RNAi) si/miRNA with antisense structure to mRNA functions in a dual role: 1) together with site-specific multi-subunit RNase, referred to as RNA-induced silencing complex (RISC), and with AGO (Argonaute) proteins si/miRNA determines an age period of endogenous mRNA molecule in each eukaryotic cell and 2) together with RISC and AGO proteins si/miRNA participates in enzymatic cleavage or in silencing of translation of homologous mRNA of pathogenic organisms providing protection against pathogens and parasites (Bakhetia et al, 2005; Chen, 2009; Fabian et al, 2010; Filipowicz et al, 2005; Hamilton et al, 2002; Park et al, 2002; Vaucheret et al, 2006; Zhang et al, 2007) Taking part in DNA methylation and histone modification during TGS, and silencing of translation of mRNA of various pathogenic organisms during PTGS, si/miRNA contributes to epigenetic inheritance of plant resistance to diseases (Calarco et al, 2012; Luna et al, 2012; Mirouze et al, 2011; Rasmann et al, 2012; Tsygankova, 2012). Targets for si/miRNA are mRNA transcripts of plant genes which expression is induced during infection ( damage of plants by phytopathogens raises), or highly homologous mRNA of pathogenic organisms (Baum et al, 2007; Hewezi et al, 2008; Katiyar-Agarwal et al, 2006; Li et al, 2012; Padmanabhan et al, 2009; Patel et al, 2010)
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