An expanded role of the SNARE-containing regulon as it relates to the defense process that Glycine max has to Heterodera glycines

Abstract

The defense regulon has been defined genetically in Arabidopsis thaliana to involve the syntaxin PENETRATION1 (PEN1), the secreted glucosidase (PEN2) and an ATP-binding cassette (ABC) transporter (PEN3). Experiments in Glycine max (soybean) have identified homologous genes being expressed in root cells undergoing defense processes to Heterodera glycines parasitism. These experiments have not examined proteins involved in cargo delivery to the infection site. A good candidate fulfilling this role would be myosin XI. In related studies, prior microscopic analyses have shown the accumulation of callose at these defense sites. Experiments presented here show that callose synthase expression impairs H. glycines parasitism. The experiments presented here have expanded on prior results demonstrating the central defense role of the plant vesicular trafficking apparatus and callose synthase to the defense process that G. max has toward H. glycines parasitism.

Exocyst components promote an incompatible interaction between Glycine max (soybean) and Heterodera glycines (the soybean cyst nematode)

“…In contrast, RNAi of G. max syntaxin 121 decreased callose deposition 34 . Subsequent follow-up studies identified the expression of 4 different CS genes in the syncytium during the defense process against H. glycines 51 . Furthermore, overexpression of the different CS genes resulted in a decrease in H. glycines parasitism, while RNAi of those same genes increased nematode parasitism 51 .…”

“…Subsequent follow-up studies identified the expression of 4 different CS genes in the syncytium during the defense process against H. glycines 51 . Furthermore, overexpression of the different CS genes resulted in a decrease in H. glycines parasitism, while RNAi of those same genes increased nematode parasitism 51 . These results provide evidence of processes requiring the exocyst to function in cells that are beyond the boundary of the syncytium during the defense response.…”

“…In A. thaliana, the vesicle transport machinery involving the exocyst acts at some level to facilitate callose deposition 18,19,52,85,[95][96][97][98][99][100][101][102] . Systemic processes outside of the vicinity of infection as well as structural modifications of G. max roots, including callose deposition and cell wall modification, have been observed 33,34,51,103 . These results are consistent with the observation that these www.nature.com/scientificreports/ components are coregulated and/or part of a feedback loop that further facilitates the expression of genes that function in the defense process 33,34 .…”

“…These results are consistent with the observation that these www.nature.com/scientificreports/ components are coregulated and/or part of a feedback loop that further facilitates the expression of genes that function in the defense process 33,34 . Over the past few years, a model of how the process of defense occurs in G. max as it reacts to H. glycines parasitism including the vesicle transport apparatus has been proposed [31][32][33][34]37,50,51 . This model has its origins in the demonstration that the 20 S component α-SNAP is specifically expressed within the syncytium during the defense process 31 .…”

“…G. max PR-1 is also under regulation by mitogen-activated protein kinases (MAPKs) 50 . The work of Austin et al 51 led to the identification of a number of G. max callose synthases (CSs) expressed within the syncytium during the defense process with functions in defense. The results demonstrated that a secreted G. max protein (PR-1) and an enzyme (CS) that generates a secreted defense molecule (callose) function during the defense response against H. glycines 51 .…”