Arabidopsis genes, AtNPR1, AtTGA2 and AtPR-5, confer partial resistance to soybean cyst nematode (Heterodera glycines) when overexpressed in transgenic soybean roots

Abstract

BackgroundExtensive studies using the model system Arabidopsis thaliana to elucidate plant defense signaling and pathway networks indicate that salicylic acid (SA) is the key hormone triggering the plant defense response against biotrophic and hemi-biotrophic pathogens, while jasmonic acid (JA) and derivatives are critical to the defense response against necrotrophic pathogens. Several reports demonstrate that SA limits nematode reproduction.ResultsHere we translate knowledge gained from studies using Arabidopsis to soybean. The ability of thirty-one Arabidopsis genes encoding important components of SA and JA synthesis and signaling in conferring resistance to soybean cyst nematode (SCN: Heterodera glycines) are investigated. We demonstrate that overexpression of three of thirty-one Arabidoposis genes in transgenic soybean roots of composite plants decreased the number of cysts formed by SCN to less than 50% of those found on control roots, namely AtNPR1(33%), AtTGA2 (38%), and AtPR-5 (38%). Three additional Arabidopsis genes decreased the number of SCN cysts by 40% or more: AtACBP3 (53% of the control value), AtACD2 (55%), and AtCM-3 (57%). Other genes having less or no effect included AtEDS5 (77%), AtNDR1 (82%), AtEDS1 (107%), and AtPR-1 (80%), as compared to control. Overexpression of AtDND1 greatly increased susceptibility as indicated by a large increase in the number of SCN cysts (175% of control).ConclusionsKnowledge of the pathogen defense system gained from studies of the model system, Arabidopsis, can be directly translated to soybean through direct overexpression of Arabidopsis genes. When the genes, AtNPR1, AtGA2, and AtPR-5, encoding specific components involved in SA regulation, synthesis, and signaling, are overexpressed in soybean roots, resistance to SCN is enhanced. This demonstrates functional compatibility of some Arabidopsis genes with soybean and identifies genes that may be used to engineer resistance to nematodes.

The heterologous expression of aGlycine maxhomolog of NONEXPRESSOR OF PR1 (NPR1) and α-hydroxynitrile glucosidase suppresses parasitism by the root pathogenMeloidogyne incognitainGossypium hirsutum

“…These results are consistent with observations showing that the heterologous expression of the A. thaliana SA signaling genes PAD4, TGA2 and NPR1 suppresses M. incognita development in G. max. Therefore, the results presented here confirm the importance of the SA signaling pathway in defense to parasitic nematodes Pant et al 2014;Matthews et al 2014). …”

“…To examine their potential role in defense, functional experiments have then been performed, demonstrating Gm-EDS1 and Gm-NPR1 function during resistance in G. max to H. glycines parasitism (Pant et al 2014). These results have been reinforced further by related experiments showing the heterologous expression of A. thaliana TGA2, PAD4 and NPR1 in G. max results in defense to H. glycines and the root knot parasitic nematode Meloidogyne incognita Matthews et al 2014). Reciprocal experiments examining whether the G. max SA signaling genes Gm-TGA2, PAD4 and NPR1 function to suppress nematode parasitism in other plant systems or whether Gm-TGA2 and Gm-PAD4 suppresses nematode parasitism in G. max were not examined Matthews et al 2014).…”

“…These experiments prove that the method works to identify candidate genes that function in G. max defense to H. glycines parasitism Matthews et al 2013Matthews et al , 2014Pant et al 2014, Pant, Krishnavajhala et al 2015. In brief, G. max [Peking/PI 548402] and G. max [PI 88788] are infected with H. glycines [NL1-Rhg/HG-type 7/race 3] , resulting in a resistant reaction as proven histologically in unengineered roots which is the natural resistance response found in these G. max genotypes (Ross 1958;Endo 1965Endo , 1991Klink et al 2007Klink et al , 2009Klink et al , 2011Klink, Hosseini et al 2010;Klink, Overall et al 2010).…”

A plant transformation system designed for high throughput genomics inGossypium hirsutumto study root–organism interactions

“…While complicating qPCR analyses, we have been able to compare roots that would normally lack the expression of a transgene completely to roots expressing the Gm-NPR1-2 transgene (absence/presence). This approach is similar to experiments that isolated genes from Arabidopsis thaliana and expressed them in G. max (Matthews et al 2014). Thus, it is possible to engineer in and test traits that are not limited to G. hirsutum genes.…”

“…The pRAP15 vector was originally developed for Agrobacterium rhizogenes-mediated root genetic engineering experiments in G. max (Matsye et al 2012;Matthews et al 2013Matthews et al , 2014Pant, Matsye, et al 2014;. The sequence of the pRAP15 vector used in the study was determined prior to the analysis (Eurofins MWG Operon, Huntsville, Alabama; Matsye et al 2012).…”