The Interaction Of Soybean Aphid And Soybean Cyst Nematode

Author : Ellie Walsh
Publisher :
ISBN 13 :
Total Pages : 188 pages
Book Rating : 4.:/5 (973 download)

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Download or read book Investigating Root-knot and Soybean Cyst Nematode Parasitic Interactions Through Transcriptomic Analyses of the Host and Parasite written by Ellie Walsh and published by . This book was released on 2016 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plant-parasitic nematodes are a major threat to global agricultural production. Root-knot nematodes (RKN, Meloidogyne spp.) are arguably the biggest threat, capable of parasitizing virtually every crop. Soybean cyst nematode (SCN; Heterodera glycines) has a narrow host range, but is the most destructive pathogen of a particularly important crop, soybean (Glycine max). RKN’s wide host range makes crop rotation often inadequate for management, and host resistance is unavailable in many crops. Effective resistance is available against SCN however populations have adapted to the most frequently used sources of resistance. RKN and SCN both induce elaborate feeding sites. In addition to being the sole source of nutrition, the feeding sites are the primary targets of nematode secretions to manipulate host cellular functions; consequently, they are very important interfaces of the interaction. The general aim of this research was to elucidate changes in the transcriptome underlying the successful interaction between these nematodes and their hosts. Although the use of RNA interference (RNAi) to knockdown nematode genes is actively being pursued as a new strategy for nematode control, little is known about the effects of general RNAi mechanisms during parasitism. As the suppression of RNAi has been characterized in other pathosystems, I hypothesized that parasitic nematodes may also be influencing these pathways. Tanscriptomic analysis of genes associated with RNAi machinery and target genes indicates that RNAi-regulated pathways are altered during the parasitic interaction. Using a silenced reporter gene, I found the disturbance to be specific to the nematode feeding site. Furthermore, disrupting these pathways with viral suppressors of RNAi renders the host more susceptible to nematode parasitism. Transcriptomic analysis indicates that this effect extends into later stages in parasitism, making the adult female stage of particular interest for further analyses. I performed a transcriptomic analysis of adult female RKN to address the hypothesis that transcriptional patterns in this later stage of parasitism will reveal new candidate genes encoding proteins that regulate the parasitic process, such as proteins that interact with RNAi among other plant pathways. Results from RNA-Seq analysis and reverse transcriptase PCR indicate that cell wall modifiers likely continue to play an important role in the parasitic interaction. Results from transcriptomic analysis including the putative secretome have highlighted new candidates for functional analysis to determine their role in the interaction. The later stage in parasitism is similarly of interest in SCN. SCN populations are adapting to the most commonly planted host resistance available in soybean, derived from Plant Introduction (PI) 88788 and “Peking.” The resistance response in PI 88788 appears to be longer-lasting than that in Peking, which impacts nematodes’ early development. Due to my focus on the adult female stage, I chose to investigate parasitism on PI 88788. I hypothesize that transcriptional differences between females from populations avirulent and virulent on PI 88788 may play a role in their adaptation to resistance. Results from this study indicate that the expression of an effector-like gene may have been lost in virulent populations, presumably allowing them to evade host detection and subsequent defense responses.