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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. [ABSTRACT FROM AUTHOR]

Expression of the central circadian oscillator components CIRCADIAN CLOCK ASSOCIATED 1 (CCA1), TIMING OF CAB1 (TOC1), GIGANTEA (GI), and CONSTANS (CO) occurs in Glycine max root cells (syncytia) parasitized by the nematode Heterodera glycines while undergoing resistance, indicating a defense role. GmCCA1-1 relative transcript abundance (RTA) in roots experiencing overexpression (OE) or RNA interference (RNAi) is characterized by rhythmic oscillations, compared to a ribosomal protein gene (GmRPS21) control. A GmCCA1-1 RTA change, advancing by 12 h, exists in H. glycines -infected as compared to uninfected controls in wild-type, H. glycines -resistant, G. max [Peking/PI 548402]. The G. max [Peking/PI 548402] transgenic controls exhibit the RTA change by 4 h post infection (hpi), not consistently occurring in the H. glycines -susceptible G. max [Williams 82/PI 518671] until 56 hpi. GmCCA1-1 expression is observed to be reduced in H. glycines -infected GmCCA1-1 -OE roots as compared to non-infected transgenic roots with no significant change observed among RNAi roots. The GmCCA1-1 expression in transgenic GmCCA1-1 -OE roots remains higher than control and RNAi roots. Decreased GmCCA1-1 mRNA among infected roots shows the altered expression is targeted by H. glycines. Gene expression of proven defense genes including 9 different mitogen activated protein kinases (GmMAPK s), NON-RACE SPECIFIC DISEASE RESISTANCE 1 (GmNDR1-1), RPM1-INTERACTING PROTEIN 4 (GmRIN4-4), and the secreted xyloglucan endotransglycosylase/hydrolase 43 (GmXTH43) in GmCCA1- 1-OE and GmCCA1-1 -RNAi roots, compared to controls, reveal a significant role of GmCCA1-1 expression in roots undergoing defense to H. glycines parasitism. The observation that GmCCA1-1 regulates GmXTH43 expression links the central circadian oscillator to the functionality of the secretion system. • Central circadian oscillator genes are expressed in nematode-parasitized root cells undergoing defense. • The overexpression of the central circadian oscillator genes suppresses parasitism. • The central circadian oscillator gene CCA1-1 regulates the expression of proven defense genes. [ABSTRACT FROM AUTHOR]

Abstract Mitogen activated protein kinases (MAPKs) play important signal transduction roles. However, little is known regarding how they influence the gene expression of other family members and the relationship to a biological process, including the Glycine max defense response to Heterodera glycines. Transcriptomics have identified MAPK gene expression occurring within root cells undergoing a defense response to a pathogenic event initiated by H. glycines in the allotetraploid Glycine max. Functional analyses are presented for its 32 MAPKs revealing 9 have a defense role, including homologs of Arabidopsis thaliana MAPK (MPK) MPK2, MPK3, MPK4, MPK5, MPK6, MPK13, MPK16 and MPK20. Defense signaling occurring through pathogen activated molecular pattern (PAMP) triggered immunity (PTI) and effector triggered immunity (ETI) have been determined in relation to these MAPKs. Five different types of gene expression relate to MAPK expression, influencing PTI and ETI gene expression and proven defense genes including an ABC-G transporter, 20S membrane fusion particle components, glycoside biosynthesis, carbon metabolism, hemicellulose modification, transcription and secretion. The experiments show MAPKs broadly influence defense MAPK gene expression, including the co-regulation of parologous MAPKs and reveal its relationship to proven defense genes. The experiments reveal each defense MAPK induces the expression of a G. max homolog of a PATHOGENESIS RELATED1 (PR1), itself shown to function in defense in the studied pathosystem. Highlights • The entire MAPK gene family has been examined functionally. • The results have identified the MAPK gene family functions as a cohort during the defense response. • The results reveal levels of co-regulated gene expression that underlie the defense response. [ABSTRACT FROM AUTHOR]