Glycine max polygalacturonase inhibiting protein 11 (GmPGIP11) functions in the root to suppress Heterodera glycines parasitism.

Pathogen-secreted polygalacturonases (PGs) alter plant cell wall structure by cleaving the α-(1 â†’ 4) linkages between D-galacturonic acid residues in homogalacturonan (HG), macerating the cell wall, facilitating infection. Plant PG inhibiting proteins (PGIPs) disengage pathogen PGs, impairing infection. The soybean cyst nematode, Heterodera glycines, obligate root parasite produces secretions, generating a multinucleate nurse cell called a syncytium, a byproduct of the merged cytoplasm of 200-250 root cells, occurring through cell wall maceration. The common cytoplasmic pool, surrounded by an intact plasma membrane, provides a source from which H. glycines derives nourishment but without killing the parasitized cell during a susceptible reaction. The syncytium is also the site of a naturally-occurring defense response that happens in specific G. max genotypes. Transcriptomic analyses of RNA isolated from the syncytium undergoing the process of defense have identified that one of the 11 G. max PGIPs, GmPGIP11, is expressed during defense. Functional transgenic analyses show roots undergoing GmPGIP11 overexpression (OE) experience an increase in its relative transcript abundance (RTA) as compared to the ribosomal protein 21 (GmRPS21) control, leading to a decrease in H. glycines parasitism as compared to the overexpression control. The GmPGIP11 undergoing RNAi experiences a decrease in its RTA as compared to the GmRPS21 control with transgenic roots experiencing an increase in H. glycines parasitism as compared to the RNAi control. Pathogen associated molecular pattern (PAMP) triggered immunity (PTI) and effector triggered immunity (ETI) components are shown to influence GmPGIP11 expression while numerous agricultural crops are shown to have homologs.

A de novo assembly of genomic dataset sequences of the sugar beet root maggot Tetanops myopaeformis, TmSBRM_v1.0.

The sugar beet root maggot (SBRM), Tetanops myopaeformis (von Röder), is a devastating insect pathogen of sugar beet (SB), Beta vulgaris, ssp vulgaris (B. vulgaris), an important food crop, while also being one of only two plants globally from which sugar is widely produced, and accounting for 35% of global raw sugar with an annual farm value of $3 billion in the United States alone. SBRM is the most devastating pathogen of sugar beet in North America. The limited natural resistance of B. vulgaris necessitates an understanding of the SBRM genome to facilitate generating knowledge of its basic biology, including the interaction between the pathogen and its host(s). Presented is the de novo assembled draft genome sequence of T. myopaeformis isolated from field-grown B. vulgaris in North Dakota, USA. The SBRM genome sequence TmSBRM_v1.0 will also be valuable for molecular genetic marker development to facilitate host resistance gene identification and knowledge, including SB polygalacturonase inhibiting protein (PGIP), and development of new control strategies for this pathogen, relationship to model genetic organisms like Drosophila melanogaster and aid in agronomic improvement of sugar beet for stakeholders while also providing information on the relationship between the SBRM and climate change.

Data analysis of polygalacturonase inhibiting proteins (PGIPs) from agriculturally important proteomes.

The plant cell wall structure can be altered by pathogen-secreted polygalacturonases (PGs) that cleave the α-(1→4) linkages occurring between D-galacturonic acid residues in homogalacturonan. The activity of the PGs leads to cell wall maceration, facilitating infection. Plant PG inhibiting proteins (PGIPs) impede pathogen PGs, impairing infection and leading to the ability of the plant to resist infection. Analyses show the Glycine max PGIP11 (GmPGIP11) is expressed within a root cell that is parasitized by the pathogenic nematode Heterodera glycines, the soybean cyst nematode (SCN), but while undergoing a defence response that leads to its demise. Transgenic experiments show GmPGIP11 overexpression leads to a successful defence response, while the overexpression of a related G. max PGIP, GmPGIP1 does not, indicating a level of specificity. The analyses presented here have identified PGIPs from 51 additional studied proteomes, many of agricultural importance. The analyses include the computational identification of signal peptides and their cleavage sites, O-, and N-glycosylation. Artificial intelligence analyses determine the location where the processed protein localize. The identified PGIPs are presented as a tool base from which functional transgenics can be performed to determine whether they may have a role in plant-pathogen interactions.

The central circadian regulator CCA1 functions in Glycine max during defense to a root pathogen, regulating the expression of genes acting in effector triggered immunity (ETI) and cell wall metabolism.

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 (GmMAPKs), 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.

The heterologous expression of conserved Glycine max (soybean) mitogen activated protein kinase 3 (MAPK3) paralogs suppresses Meloidogyne incognita parasitism in Gossypium hirsutum (upland cotton).

Two conserved Glycine max (soybean) mitogen activated protein kinase 3 (MAPK3) paralogs function in defense to the parasitic soybean cyst nematode Heterodera glycines. Gene Ontology analyses of RNA seq data obtained from MAPK3-1-overexpressing (OE) and MAPK3-2-OE roots compared to their control, as well as MAPK3-1-RNA interference (RNAi) and MAPK3-2-RNAi compared to their control, hierarchically orders the induced and suppressed genes, strengthening the hypothesis that their heterologous expression in Gossypium hirsutum (upland cotton) would impair parasitism by the root knot nematode (RKN) Meloidogyne incognita. MAPK3-1 expression (E) in G. hirsutum suppresses the production of M. incognita root galls, egg masses, and second stage juveniles (J2s) by 80.32%, 82.37%, and 88.21%, respectfully. Unexpectedly, egg number increases by 28.99% but J2s are inviable. MAPK3-2-E effects are identical, statistically. MAPK3-1-E and MAPK3-2-E decreases root mass 1.49-fold and 1.55-fold, respectively, as compared to the pRAP15-ccdB-E control. The reproductive factor (RF) of M. incognita for G. hirsutum roots expressing MAPK3-1-E or MAPK3-2-E decreases 60.39% and 50.46%, respectively, compared to controls. The results are consistent with upstream pathogen activated molecular pattern (PAMP) triggered immunity (PTI) and effector triggered immunity (ETI) functioning in defense to H. glycines. The experiments showcase the feasibility of employing MAPK3, through heterologous expression, to combat M. incognita parasitism, possibly overcoming impediments otherwise making G. hirsutum's defense platform deficient. MAPK homologs are identified in other important crop species for future functional analyses.

Glycine max Homologs of DOESN'T MAKE INFECTIONS 1, 2, and 3 Function to Impair Heterodera glycines Parasitism While Also Regulating Mitogen Activated Protein Kinase Expression.

Glycine max root cells developing into syncytia through the parasitic activities of the pathogenic nematode Heterodera glycines underwent isolation by laser microdissection (LM). Microarray analyses have identified the expression of a G. max DOESN'T MAKE INFECTIONS3 (DMI3) homolog in syncytia undergoing parasitism but during a defense response. DMI3 encodes part of the common symbiosis pathway (CSP) involving DMI1, DMI2, and other CSP genes. The identified DMI gene expression, and symbiosis role, suggests the possible existence of commonalities between symbiosis and defense. G. max has 3 DMI1, 12 DMI2, and 2 DMI3 paralogs. LM-assisted gene expression experiments of isolated syncytia under further examination here show G. max DMI1-3, DMI2-7, and DMI3-2 expression occurring during the defense response in the H. glycines-resistant genotypes G.max [Peking/PI548402] and G.max [PI88788] indicating a broad and consistent level of expression of the genes. Transgenic overexpression (OE) of G. max DMI1-3, DMI2-7, and DMI3-2 impairs H. glycines parasitism. RNA interference (RNAi) of G. max DMI1-3, DMI2-7, and DMI3-2 increases H. glycines parasitism. The combined opposite outcomes reveal a defense function for these genes. Prior functional transgenic analyses of the 32-member G. max mitogen activated protein kinase (MAPK) gene family has determined that 9 of them act in the defense response to H. glycines parasitism, referred to as defense MAPKs. RNA-seq analyses of root RNA isolated from the 9 G. max defense MAPKs undergoing OE or RNAi reveal they alter the relative transcript abundances (RTAs) of specific DMI1, DMI2, and DMI3 paralogs. In contrast, transgenically-manipulated DMI1-3, DMI2-7, and DMI3-2 expression influences MAPK3-1 and MAPK3-2 RTAs under certain circumstances. The results show G. max homologs of the CSP, and defense pathway are linked, apparently involving co-regulated gene expression.

Conserved oligomeric Golgi (COG) complex genes functioning in defense are expressed in root cells undergoing a defense response to a pathogenic infection and exhibit regulation my MAPKs.

The conserved oligomeric Golgi (COG) complex maintains correct Golgi structure and function during retrograde trafficking. Glycine max has 2 paralogs of each COG gene, with one paralog of each gene family having a defense function to the parasitic nematode Heterodera glycines. Experiments presented here show G. max COG paralogs functioning in defense are expressed specifically in the root cells (syncytia) undergoing the defense response. The expressed defense COG gene COG7-2-b is an alternate splice variant, indicating specific COG variants are important to defense. Transcriptomic experiments examining RNA isolated from COG overexpressing and RNAi roots show some COG genes co-regulate the expression of other COG complex genes. Examining signaling events responsible for COG expression, transcriptomic experiments probing MAPK overexpressing roots show their expression influences the relative transcript abundance of COG genes as compared to controls. COG complex paralogs are shown to be found in plants that are agriculturally relevant on a world-wide scale including Manihot esculenta, Zea mays, Oryza sativa, Triticum aestivum, Hordeum vulgare, Sorghum bicolor, Brassica rapa, Elaes guineensis and Saccharum officinalis and in additional crops significant to U.S. agriculture including Beta vulgaris, Solanum tuberosum, Solanum lycopersicum and Gossypium hirsutum. The analyses provide basic information on COG complex biology, including the coregulation of some COG genes and that MAPKs functioning in defense influence their expression. Furthermore, it appears in G. max and likely other crops that some level of neofunctionalization of the duplicated genes is occurring. The analysis has identified important avenues for future research broadly in plants.

Xyloglucan endotransglycosylase/hydrolase increases tightly-bound xyloglucan and chain number but decreases chain length contributing to the defense response that Glycine max has to Heterodera glycines.

The Glycine max xyloglucan endotransglycosylase/hydrolase (EC 2.4.1.207), GmXTH43, has been identified through RNA sequencing of RNA isolated through laser microdissection of Heterodera glycines-parasitized root cells (syncytia) undergoing the process of defense. Experiments reveal that genetically increasing XTH43 transcript abundance in the H. glycines-susceptible genotype G. max[Williams 82/PI 518671] decreases parasitism. Experiments presented here show decreasing XTH43 transcript abundance through RNA interference (RNAi) in the H. glycines-resistant G. max[Peking/PI 548402] increases susceptibility, but it is unclear what role XTH43 performs. The experiments presented here show XTH43 overexpression decreases the relative length of xyloglucan (XyG) chains, however, there is an increase in the amount of those shorter chains. In contrast, XTH43 RNAi increases XyG chain length. The experiments show that XTH43 has the capability to function, when increased in its expression, to limit XyG chain extension. This outcome would likely impair the ability of the cell wall to expand. Consequently, XTH43 could provide an enzymatically-driven capability to the cell that would allow it to limit the ability of parasitic nematodes like H. glycines to develop a feeding structure that, otherwise, would facilitate parasitism. The experiments presented here provide experimentally-based proof that XTHs can function in ways that could be viewed as being able to limit the expansion of the cell wall.

The Glycine max Conserved Oligomeric Golgi (COG) Complex Functions During a Defense Response to Heterodera glycines.

The conserved oligomeric Golgi (COG) complex, functioning in retrograde trafficking, is a universal structure present among eukaryotes that maintains the correct Golgi structure and function. The COG complex is composed of eight subunits coalescing into two sub-complexes. COGs1-4 compose Sub-complex A. COGs5-8 compose Sub-complex B. The observation that COG interacts with the syntaxins, suppressors of the erd2-deletion 5 (Sed5p), is noteworthy because Sed5p also interacts with Sec17p [alpha soluble NSF attachment protein (α-SNAP)]. The α-SNAP gene is located within the major Heterodera glycines [soybean cyst nematode (SCN)] resistance locus (rhg1) and functions in resistance. The study presented here provides a functional analysis of the Glycine max COG complex. The analysis has identified two paralogs of each COG gene. Functional transgenic studies demonstrate at least one paralog of each COG gene family functions in G. max during H. glycines resistance. Furthermore, treatment of G. max with the bacterial effector harpin, known to function in effector triggered immunity (ETI), leads to the induced transcription of at least one member of each COG gene family that has a role in H. glycines resistance. In some instances, altered COG gene expression changes the relative transcript abundance of syntaxin 31. These results indicate that the G. max COG complex functions through processes involving ETI leading to H. glycines resistance.

Mitogen activated protein kinase (MAPK)-regulated genes with predicted signal peptides function in the Glycine max defense response to the root pathogenic nematode Heterodera glycines.

Glycine max has 32 mitogen activated protein kinases (MAPKs), nine of them exhibiting defense functions (defense MAPKs) to the plant parasitic nematode Heterodera glycines. RNA seq analyses of transgenic G. max lines overexpressing (OE) each defense MAPK has led to the identification of 309 genes that are increased in their relative transcript abundance by all 9 defense MAPKs. Here, 71 of those genes are shown to also have measurable amounts of transcript in H. glycines-induced nurse cells (syncytia) produced in the root that are undergoing a defense response. The 71 genes have been grouped into 7 types, based on their expression profile. Among the 71 genes are 8 putatively-secreted proteins that include a galactose mutarotase-like protein, pollen Ole e 1 allergen and extensin protein, endomembrane protein 70 protein, O-glycosyl hydrolase 17 protein, glycosyl hydrolase 32 protein, FASCICLIN-like arabinogalactan protein 17 precursor, secreted peroxidase and a pathogenesis-related thaumatin protein. Functional transgenic analyses of all 8 of these candidate defense genes that employ their overexpression and RNA interference (RNAi) demonstrate they have a role in defense. Overexpression experiments that increase the relative transcript abundance of the candidate defense gene reduces the ability that the plant parasitic nematode Heterodera glycines has in completing its life cycle while, in contrast, RNAi of these genes leads to an increase in parasitism. The results provide a genomic analysis of the importance of MAPK signaling in relation to the secretion apparatus during the defense process defense in the G. max-H. glycines pathosystem and identify additional targets for future studies.

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

Vesicle and target membrane fusion involves tethering, docking and fusion. The GTPase SECRETORY4 (SEC4) positions the exocyst complex during vesicle membrane tethering, facilitating docking and fusion. Glycine max (soybean) Sec4 functions in the root during its defense against the parasitic nematode Heterodera glycines as it attempts to develop a multinucleate nurse cell (syncytium) serving to nourish the nematode over its 30-day life cycle. Results indicate that other tethering proteins are also important for defense. The G. max exocyst is encoded by 61 genes: 5 EXOC1 (Sec3), 2 EXOC2 (Sec5), 5 EXOC3 (Sec6), 2 EXOC4 (Sec8), 2 EXOC5 (Sec10) 6 EXOC6 (Sec15), 31 EXOC7 (Exo70) and 8 EXOC8 (Exo84) genes. At least one member of each gene family is expressed within the syncytium during the defense response. Syncytium-expressed exocyst genes function in defense while some are under transcriptional regulation by mitogen-activated protein kinases (MAPKs). The exocyst component EXOC7-H4-1 is not expressed within the syncytium but functions in defense and is under MAPK regulation. The tethering stage of vesicle transport has been demonstrated to play an important role in defense in the G. max-H. glycines pathosystem, with some of the spatially and temporally regulated exocyst components under transcriptional control by MAPKs.

The heterologous expression of a soybean (Glycine max) xyloglucan endotransglycosylase/hydrolase (XTH) in cotton (Gossypium hirsutum) suppresses parasitism by the root knot nematode Meloidogyne incognita.

A Glycine max (soybean) hemicellulose modifying gene, xyloglucan endotransglycoslase/hydrolase (XTH43), has been identified as being expressed within a nurse cell known as a syncytium developing within the soybean root undergoing the process of defense to infection by the parasitic nematode, Heterodera glycines. The highly effective nature of XTH43 overexpression in suppressing H. glycines parasitism in soybean has led to experiments examining whether the heterologous expression of XTH43 in Gossypium hirsutum (upland cotton) could impair the parasitism of Meloidogyne incognita, that form a different type of nurse cell called a giant cell that is enclosed within a swollen root structure called a gall. The heterologous transgenic expression of XTH43 in cotton resulted in an 18% decrease in the number of galls, 70% decrease in egg masses, 64% decrease in egg production and a 97% decrease in second stage juvenile (J2) production as compared to transgenic controls. The heterologous XTH43 expression does not significantly affect root mass. The results demonstrate XTH43 expression functions effectively in impairing the development of M. incognita at numerous life cycle stages occurring within the cotton root. The experiments reveal that there are highly conserved aspects of the defense response of G. max that can function effectively in G. hirsutum to impair M. incognita having a different method of parasitism.

MAPKDB: A MAP kinase database for signal transduction element identification.

The mitogen activated protein kinase (MAPK) cascade is a central signal transduction platform, ubiquitous within the eukaryotes. MAPKs function prominently in different essential cellular processes such as proliferation, differentiation, survival and defense to pathogen attack. The 32 MAPKs of Glycine max (soybean) have been examined functionally to determine if they have any defense role, focusing in on infection by the plant-parasitic nematode Heterodera glycines. Of these 32 MAPKs, 9 have been shown to have a defense function. Hence, the Mitogen Activated Protein Kinase database (MAPKDB) has been developed to assist in such research. The MAPKDB allows users to search the annotations with sequence data for G. max transgenic lines undergoing overexpression (OE) or RNA interference (RNAi) of its defense map kinases. These defense MAPKs include map kinase 2 (MPK2), MPK3, MPK4, MPK5, MPK6, MPK13, MPK16, and MPK20. The database also contains data analysis information for each sample that helps to detect the differential expression of the genes identified within these samples. The database also contains data for each sample that helps to detect the differential expression of the genes identified within these samples. The database has been developed to manage G. max MAPK sequences with sequence alignment for 18 different samples along with two additional OE and RNAi control experiments for a total of 20.

The mitogen activated protein kinase (MAPK) gene family functions as a cohort during the Glycine max defense response to Heterodera glycines.

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.

Testing the AC/DC hypothesis: Rock and roll is noise pollution and weakens a trophic cascade.

Anthropogenic sound is increasingly considered a major environmental issue, but its effects are relatively unstudied. Organisms may be directly affected by anthropogenic sound in many ways, including interference with their ability to detect mates, predators, or food, and disturbances that directly affect one organism may in turn have indirect effects on others. Thus, to fully appreciate the net effect of anthropogenic sound, it may be important to consider both direct and indirect effects. We report here on a series of experiments to test the hypothesis that anthropogenic sound can generate cascading indirect effects within a community. We used a study system of lady beetles, soybean aphids, and soybean plants, which are a useful model for studying the direct and indirect effects of global change on food webs. For sound treatments, we used several types of music, as well as a mix of urban sounds (e.g., sirens, vehicles, and construction equipment), each at volumes comparable to a busy city street or farm tractor. In 18-hr feeding trials, rock music and urban sounds caused lady beetles to consume fewer aphids, but other types of music had no effect even at the same volume. We then tested the effect of rock music on the strength of trophic cascades in a 2-week experiment in plant growth chambers. When exposed to music by AC/DC, who articulated the null hypothesis that "rock and roll ain't noise pollution" in a song of the same name, lady beetles were less effective predators, resulting in higher aphid density and reduced final plant biomass relative to control (no music) treatments. While it is unclear what characteristics of sound generate these effects, our results reject the AC/DC hypothesis and demonstrate that altered interspecific interactions can transmit the indirect effects of anthropogenic noise through a community.

Harpin-inducible defense signaling components impair infection by the ascomycete Macrophomina phaseolina.

Soybean (Glycine max) infection by the charcoal rot (CR) ascomycete Macrophomina phaseolina is enhanced by the soybean cyst nematode (SCN) Heterodera glycines. We hypothesized that G. max genetic lines impairing infection by M. phaseolina would also limit H. glycines parasitism, leading to resistance. As a part of this M. phaseolina resistance process, the genetic line would express defense genes already proven to impair nematode parasitism. Using G. max[DT97-4290/PI 642055], exhibiting partial resistance to M. phaseolina, experiments show the genetic line also impairs H. glycines parasitism. Furthermore, comparative studies show G. max[DT97-4290/PI 642055] exhibits induced expression of the effector triggered immunity (ETI) gene NON-RACE SPECIFIC DISEASE RESISTANCE 1/HARPIN INDUCED1 (NDR1/HIN1) that functions in defense to H. glycines as compared to the H. glycines and M. phaseolina susceptible line G. max[Williams 82/PI 518671]. Other defense genes that are induced in G. max[DT97-4290/PI 642055] include the pathogen associated molecular pattern (PAMP) triggered immunity (PTI) genes ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1), NONEXPRESSOR OF PR1 (NPR1) and TGA2. These observations link G. max defense processes that impede H. glycines parasitism to also potentially function toward impairing M. phaseolina pathogenicity. Testing this hypothesis, G. max[Williams 82/PI 518671] genetically engineered to experimentally induce GmNDR1-1, EDS1-2, NPR1-2 and TGA2-1 expression leads to impaired M. phaseolina pathogenicity. In contrast, G. max[DT97-4290/PI 642055] engineered to experimentally suppress the expression of GmNDR1-1, EDS1-2, NPR1-2 and TGA2-1 by RNA interference (RNAi) enhances M. phaseolina pathogenicity. The results show components of PTI and ETI impair both nematode and M. phaseolina pathogenicity.

A harpin elicitor induces the expression of a coiled-coil nucleotide binding leucine rich repeat (CC-NB-LRR) defense signaling gene and others functioning during defense to parasitic nematodes.

The bacterial effector harpin induces the transcription of the Arabidopsis thaliana NON-RACE SPECIFIC DISEASE RESISTANCE 1/HARPIN INDUCED1 (NDR1/HIN1) coiled-coil nucleotide binding leucine rich repeat (CC-NB-LRR) defense signaling gene. In Glycine max, Gm-NDR1-1 transcripts have been detected within root cells undergoing a natural resistant reaction to parasitism by the syncytium-forming nematode Heterodera glycines, functioning in the defense response. Expressing Gm-NDR1-1 in Gossypium hirsutum leads to resistance to Meloidogyne incognita parasitism. In experiments presented here, the heterologous expression of Gm-NDR1-1 in G. hirsutum impairs Rotylenchulus reniformis parasitism. These results are consistent with the hypothesis that Gm-NDR1-1 expression functions broadly in generating a defense response. To examine a possible relationship with harpin, G. max plants topically treated with harpin result in induction of the transcription of Gm-NDR1-1. The result indicates the topical treatment of plants with harpin, itself, may lead to impaired nematode parasitism. Topical harpin treatments are shown to impair G. max parasitism by H. glycines, M. incognita and R. reniformis and G. hirsutum parasitism by M. incognita and R. reniformis. How harpin could function in defense has been examined in experiments showing it also induces transcription of G. max homologs of the proven defense genes ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1), TGA2, galactinol synthase, reticuline oxidase, xyloglucan endotransglycosylase/hydrolase, alpha soluble N-ethylmaleimide-sensitive fusion protein (α-SNAP) and serine hydroxymethyltransferase (SHMT). In contrast, other defense genes are not directly transcriptionally activated by harpin. The results indicate harpin induces pathogen associated molecular pattern (PAMP) triggered immunity (PTI) and effector-triggered immunity (ETI) defense processes in the root, activating defense to parasitic nematodes.

A Glycine max homolog of NON-RACE SPECIFIC DISEASE RESISTANCE 1 (NDR1) alters defense gene expression while functioning during a resistance response to different root pathogens in different genetic backgrounds.

A Glycine max homolog of the Arabidopsis thaliana NON-RACE SPECIFIC DISEASE RESISTANCE 1 (NDR1) coiled-coil nucleotide binding leucine rich repeat (CC-NB-LRR) defense signaling gene (Gm-NDR1-1) is expressed in root cells undergoing a defense response to the root pathogenic nematode, Heterodera glycines. Gm-NDR1-1 overexpression in the H. glycines-susceptible genotype G. max[Williams 82/PI 518671] impairs parasitism. In contrast, Gm-NDR1-1 RNA interference (RNAi) in the H. glycines-resistant genotype G. max[Peking/PI 548402] facilitates parasitism. The broad effectiveness of Gm-NDR1-1 in impairing parasitism has then been examined by engineering its heterologous expression in Gossypium hirsutum which is susceptible to the root pathogenic nematode Meloidogyne incognita. The heterologous expression of Gm-NDR1-1 in G. hirsutum effectively impairs M. incognita parasitism, reducing gall, egg mass, egg and juvenile numbers. In contrast to our prior experiments examining the effectiveness of the heterologous expression of a G. max homolog of the A. thaliana salicyclic acid signaling (SA) gene NONEXPRESSOR OF PR1 (Gm-NPR1-2), no cumulative negative effect on M. incognita parasitism has been observed in G. hirsutum expressing Gm-NDR1-1. The results indicate a common genetic basis exists for plant resistance to parasitic nematodes that involves Gm-NDR1. However, the Gm-NDR1-1 functions in ways that are measurably dissimilar to Gm-NPR1-2. Notably, Gm-NDR1-1 overexpression leads to increased relative transcript levels of its homologs of A. thaliana genes functioning in SA signaling, including NPR1-2, TGA2-1 and LESION SIMULATING DISEASE1 (LSD1-2) that is lost in Gm-NDR1-1 RNAi lines. Similar observations have been made regarding the expression of other defense genes.

Components of the SNARE-containing regulon are co-regulated in root cells undergoing defense.

The term regulon has been coined in the genetic model plant Arabidopsis thaliana, denoting a structural and physiological defense apparatus defined genetically through the identification of the penetration (pen) mutants. The regulon is composed partially by the soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) syntaxin PEN1. PEN1 has homology to a Saccharomyces cerevisae gene that regulates a Secretion (Sec) protein, Suppressor of Sec 1 (Sso1p). The regulon is also composed of the ß-glucosidase (PEN2) and an ATP binding cassette (ABC) transporter (PEN3). While important in inhibiting pathogen infection, limited observations have been made regarding the transcriptional regulation of regulon genes until now. Experiments made using the model agricultural Glycine max (soybean) have identified co-regulated gene expression of regulon components. The results explain the observation of hundreds of genes expressed specifically in the root cells undergoing the natural process of defense. Data regarding additional G. max genes functioning within the context of the regulon are presented here, including Sec 14, Sec 4 and Sec 23. Other examined G. max homologs of membrane fusion genes include an endosomal bromo domain-containing protein1 (Bro1), syntaxin6 (SYP6), SYP131, SYP71, SYP8, Bet1, coatomer epsilon (ϵ-COP), a coatomer zeta (ζ-COP) paralog and an ER to Golgi component (ERGIC) protein. Furthermore, the effectiveness of biochemical pathways that would function within the context of the regulon ave been examined, including xyloglucan xylosyltransferase (XXT), reticuline oxidase (RO) and galactinol synthase (GS). The experiments have unveiled the importance of the regulon during defense in the root and show how the deposition of callose relates to the process.

The syntaxin 31-induced gene, LESION SIMULATING DISEASE1 (LSD1), functions in Glycine max defense to the root parasite Heterodera glycines.

Experiments show the membrane fusion genes α soluble NSF attachment protein (α-SNAP) and syntaxin 31 (Gm-SYP38) contribute to the ability of Glycine max to defend itself from infection by the plant parasitic nematode Heterodera glycines. Accompanying their expression is the transcriptional activation of the defense genes ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and NONEXPRESSOR OF PR1 (NPR1) that function in salicylic acid (SA) signaling. These results implicate the added involvement of the antiapoptotic, environmental response gene LESION SIMULATING DISEASE1 (LSD1) in defense. Roots engineered to overexpress the G. max defense genes Gm-α-SNAP, SYP38, EDS1, NPR1, BOTRYTIS INDUCED KINASE1 (BIK1) and xyloglucan endotransglycosylase/hydrolase (XTH) in the susceptible genotype G. max[Williams 82/PI 518671] have induced Gm-LSD1 (Gm-LSD1-2) transcriptional activity. In reciprocal experiments, roots engineered to overexpress Gm-LSD1-2 in the susceptible genotype G. max[Williams 82/PI 518671] have induced levels of SYP38, EDS1, NPR1, BIK1 and XTH, but not α-SNAP prior to infection. In tests examining the role of Gm-LSD1-2 in defense, its overexpression results in ∼52 to 68% reduction in nematode parasitism. In contrast, RNA interference (RNAi) of Gm-LSD1-2 in the resistant genotype G. max[Peking/PI 548402] results in an 3.24-10.42 fold increased ability of H. glycines to parasitize. The results identify that Gm-LSD1-2 functions in the defense response of G. max to H. glycines parasitism. It is proposed that LSD1, as an antiapoptotic protein, may establish an environment whereby the protected, living plant cell could secrete materials in the vicinity of the parasitizing nematode to disarm it. After the targeted incapacitation of the nematode the parasitized cell succumbs to its targeted demise as the infected root region is becoming fortified.