Publications by authors named "Kathy S Lawrence"

22 Publications

  • Page 1 of 1

Evaluation of a new chemical nematicide, fluazaindolizine (ReklemelTM active), for plant-parasitic nematode management in bermudagrass.

J Nematol 2021 1;53. Epub 2021 Apr 1.

559 Devall Dr. CASIC Building, Auburn, AL, Auburn University 36849.

Plant-parasitic nematodes are a major pest of turfgrass in the United States, yet there are few options for successful management. Most current management strategies rely on the use of a limited number of chemical nematicides, so finding a new management option for nematode suppression would be extremely valuable for turfgrass managers. The aim of this study is to evaluate a new nematicide, fluazaindolizine (Reklemel™ active), for its ability to reduce plant-parasitic nematode population density and improve turfgrass quality. Separate research trials were conducted on bermudagrass infested with and in greenhouse, microplot, and field settings over 2018 and 2019. Both greenhouse evaluations demonstrated multiple rates of fluazaindolizine reduced population density, and one of the two trials showed multiple rates of fluazaindolizine reduced nematode population density. Fluazaindolizine was also effective at reducing population density of both and in microplot settings for both 2018 and 2019, and a significant improvement in turf quality was observed for both visual turfgrass ratings and NDVI. Field trials demonstrated a significant reduction for both and population density by multiple rates of fluazaindolizine, but no significant differences in turf quality ratings were observed. Overall, fluazaindolizine shows promise as a chemical nematicide for plant-parasitic nematode management on turfgrass.
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http://dx.doi.org/10.21307/jofnem-2021-043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8040137PMC
April 2021

Plant health evaluations of and colonized bermudagrass using remote sensing.

J Nematol 2020 6;52. Epub 2020 Nov 6.

Auburn University, 209 Rouse Life Science Building, Auburn, AL, 36849.

The objective of this study was to evaluate the ability of an unmanned aerial system (UAS) equipped with a multispectral sensor to track plant health in the presence of plant-parasitic nematodes in conjunction with nematicide applications. Four nematicides were evaluated for their ability to suppress and in microplots, and three nematicides were evaluated on a golf course for their ability to suppress multiple plant-parasitic nematode genera. Visual ratings, Normalized Difference Vegetation Index (NDVI), and Normalized Difference RedEdge Index (NDRE) were reported throughout the trial to assess plant health. and population density was significantly lowered by nematicide treatments in microplots and correlated with visual ratings, NDVI, and NDRE plant health ratings. On the golf course, all nematicides reduced total plant-parasitic nematode population density at 28, 56, and 84 days after treatment (DAT). Visual turf quality ratings, NDVI, and NDRE were positively correlated with lower nematode population density in the majority of evaluation dates. In the microplot and golf course settings, the parameters evaluated for plant health were correlated with plant-parasitic nematode population density: visual ratings, NDVI, and NDRE improved as nematode population density declined. These results show that remote sensing has the potential to be a beneficial tool for assessing plant-parasitic nematode infected bermudagrass.
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http://dx.doi.org/10.21307/jofnem-2020-109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8015358PMC
November 2020

The Conserved Oligomeric Golgi (COG) Complex Functions During a Defense Response to .

Front Plant Sci 2020 11;11:564495. Epub 2020 Nov 11.

Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Starkville, MS, United States.

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 [soybean cyst nematode (SCN)] resistance locus () and functions in resistance. The study presented here provides a functional analysis of the 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 during resistance. Furthermore, treatment of 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 resistance. In some instances, altered COG gene expression changes the relative transcript abundance of syntaxin 31. These results indicate that the COG complex functions through processes involving ETI leading to resistance.
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http://dx.doi.org/10.3389/fpls.2020.564495DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7686354PMC
November 2020

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

Sci Rep 2020 09 14;10(1):15003. Epub 2020 Sep 14.

Department of Biological Sciences, Mississippi State University, Mississippi State, MS, 39762, USA.

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.
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http://dx.doi.org/10.1038/s41598-020-72126-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7490361PMC
September 2020

Current Utility of Plant Growth-Promoting Rhizobacteria as Biological Control Agents towards Plant-Parasitic Nematodes.

Plants (Basel) 2020 Sep 9;9(9). Epub 2020 Sep 9.

Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA.

Plant-parasitic nematodes (PPN) are among the most economically and ecologically damaging pests, causing severe losses of crop production worldwide. Chemical-based nematicides have been widely used, but these may have adverse effects on human health and the environment. Hence, biological control agents (BCAs) have become an alternative option for controlling PPN, since they are environmentally friendly and cost effective. Lately, a major effort has been made to evaluate the potential of a commercial grade strain of plant growth-promoting rhizobacteria (PGPR) as BCAs, because emerging evidence has shown that PGPR can reduce PPN in infested plants through direct and/or indirect antagonistic mechanisms. Direct antagonism occurs by predation, release of antinematicidal metabolites and semiochemicals, competition for nutrients, and niche exclusion. However, the results of direct antagonism may be inconsistent due to unknown endogenous and exogenous factors that may prevent PGPR from colonizing plant's roots. On the other hand, indirect antagonism may occur from the induced systemic resistance (ISR) that primes whole plants to better fight against various biotic and abiotic constraints, actuating faster and/or stronger defense responses (adaption), enhancing their promise as BCAs. Hence, this review will briefly revisit (i) two modes of PGPR in managing PPN, and (ii) the current working models and many benefits of ISR, in the aim of reassessing current progresses and future directions for isolating more effective BCAs and/or developing better PPN management strategy.
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http://dx.doi.org/10.3390/plants9091167DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7569769PMC
September 2020

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

Plant Physiol Biochem 2019 Apr 28;137:25-41. Epub 2019 Jan 28.

Department of Biological Sciences, Mississippi State University, Mississippi State, MS, 39762, USA. Electronic address:

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.
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http://dx.doi.org/10.1016/j.plaphy.2019.01.018DOI Listing
April 2019

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

Plant Physiol Biochem 2018 Aug 18;129:331-348. Epub 2018 Jun 18.

Department of Biological Sciences, College of Arts and Sciences, Mississippi State University, Mississippi State, MS, 39762, USA. Electronic address:

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, exhibiting partial resistance to M. phaseolina, experiments show the genetic line also impairs H. glycines parasitism. Furthermore, comparative studies show G. max 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. Other defense genes that are induced in G. max 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 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 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.
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http://dx.doi.org/10.1016/j.plaphy.2018.06.020DOI Listing
August 2018

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.

Plant Physiol Biochem 2017 Dec 13;121:161-175. Epub 2017 Oct 13.

Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, United States. Electronic address:

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.
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http://dx.doi.org/10.1016/j.plaphy.2017.10.004DOI Listing
December 2017

Biological control of Heterodera glycines by spore-forming plant growth-promoting rhizobacteria (PGPR) on soybean.

PLoS One 2017 13;12(7):e0181201. Epub 2017 Jul 13.

Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America.

Heterodera glycines, the soybean cyst nematode, is the most economically important plant-parasitic nematode on soybean production in the U.S. The objectives of this study were to evaluate the potential of plant growth-promoting rhizobacteria (PGPR) strains for mortality of H. glycines J2 in vitro and for reducing nematode population density on soybean in greenhouse, microplot, and field trials. The major group causing mortality to H. glycines in vitro was the genus Bacillus that consisted of 92.6% of the total 663 PGPR strains evaluated. The subsequent greenhouse, microplot, and field trials indicated that B. velezensis strain Bve2 consistently reduced H. glycines cyst population density at 60 DAP. Bacillus mojavensis strain Bmo3 suppressed H. glycines cyst and total H. glycines population density under greenhouse conditions. Bacillus safensis strain Bsa27 and Mixture 1 (Bve2 + Bal13) reduced H. glycines cyst population density at 60 DAP in the field trials. Bacillus subtilis subsp. subtilis strains Bsssu2 and Bsssu3, and B. velezensis strain Bve12 increased early soybean growth including plant height and plant biomass in the greenhouse trials. Bacillus altitudinis strain Bal13 increased early plant growth on soybean in the greenhouse and microplot trials. Mixture 2 (Abamectin + Bve2 + Bal13) increased early plant growth in the microplot trials at 60 DAP, and also enhanced soybean yield at harvest in the field trials. These results demonstrated that individual PGPR strains and mixtures can reduce H. glycines population density in the greenhouse, microplot, and field conditions, and increased yield of soybean.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0181201PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5509290PMC
September 2017

Biological Control of Meloidogyne incognita by Spore-forming Plant Growth-promoting Rhizobacteria on Cotton.

Plant Dis 2017 May 16;101(5):774-784. Epub 2017 Feb 16.

Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State 39762.

In the past decade, increased attention has been placed on biological control of plant-parasitic nematodes using various fungi and bacteria. The objectives of this study were to evaluate the potential of 662 plant growth-promoting rhizobacteria (PGPR) strains for mortality to Meloidogyne incognita J2 in vitro and for nematode management in greenhouse, microplot, and field trials. Results indicated that the mortality of M. incognita J2 by the PGPR strains ranged from 0 to 100% with an average of 39%. Among the PGPR strains examined, 212 of 662 strains (or 33%) caused significantly greater mortality percent of M. incognita J2 than the untreated control. Bacillus was the major genus initiating a greater mortality percentage when compared with the other genera. In subsequent trials, B. velezensis strain Bve2 reduced M. incognita eggs per gram of cotton root in the greenhouse trials at 45 days after planting (DAP) similarly to the commercial standards Abamectin and Clothianidin plus B. firmus I-1582. Bacillus mojavensis strain Bmo3, B. velezensis strain Bve2, B. subtilis subsp. subtilis strain Bsssu3, and the Mixture 2 (Abamectin + Bve2 + B. altitudinis strain Bal13) suppressed M. incognita eggs per gram of root in the microplot at 45 DAP. Bacillus velezensis strains Bve2 and Bve12 also increased seed-cotton yield in the microplot and field trials. Overall, results indicate that B. velezensis strains Bve2 and Bve12, B. mojavensis strain Bmo3, and Mixture 2 have potential to reduce M. incognita population density and to enhance growth of cotton when applied as in-furrow sprays at planting.
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http://dx.doi.org/10.1094/PDIS-09-16-1369-REDOI Listing
May 2017

Principal Component Analysis and Molecular Characterization of Reniform Nematode Populations in Alabama.

Plant Pathol J 2016 Apr 1;32(2):123-35. Epub 2016 Apr 1.

Department of Natural Resources and Environmental Sciences, Alabama A & M University, Normal-AL, 35762.

U.S. cotton production is suffering from the yield loss caused by the reniform nematode (RN), Rotylenchulus reniformis. Management of this devastating pest is of utmost importance because, no upland cotton cultivar exhibits adequate resistance to RN. Nine populations of RN from distinct regions in Alabama and one population from Mississippi were studied and thirteen morphometric features were measured on 20 male and 20 female nematodes from each population. Highly correlated variables (positive) in female and male RN morphometric parameters were observed for body length (L) and distance of vulva from the lip region (V) (r = 0.7) and tail length (TL) and c' (r = 0.8), respectively. The first and second principal components for the female and male populations showed distinct clustering into three groups. These results show pattern of sub-groups within the RN populations in Alabama. A one-way ANOVA on female and male RN populations showed significant differences (p ≤ 0.05) among the variables. Multiple sequence alignment (MSA) of 18S rRNA sequences (421) showed lengths of 653 bp. Sites within the aligned sequences were conserved (53%), parsimony-informative (17%), singletons (28%), and indels (2%), respectively. Neighbor-Joining analysis showed intra and inter-nematodal variations within the populations as clone sequences from different nematodes irrespective of the sex of nematode isolate clustered together. Morphologically, the three groups (I, II and III) could not be distinctly associated with the molecular data from the 18S rRNA sequences. The three groups may be identified as being non-geographically contiguous.
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http://dx.doi.org/10.5423/PPJ.OA.09.2015.0194DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4853102PMC
April 2016

Optimization of In Vitro Techniques for Distinguishing between Live and Dead Second Stage Juveniles of Heterodera glycines and Meloidogyne incognita.

PLoS One 2016 4;11(5):e0154818. Epub 2016 May 4.

Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America.

Heterodera glycines (Soybean Cyst nematode, or SCN) and Meloidogyne incognita (Root-Knot nematode, or RKN) are two damaging plant-parasitic nematodes on important field crops. Developing a quick method to distinguish between live and dead SCN and RKN second stage juveniles (J2) is vital for high throughput screening of pesticides or biological compounds against SCN and RKN. The in vitro assays were conducted in 96-well plates to determine the optimum chemical stimulus to distinguish between live and dead SCN and RKN J2. Sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), and sodium hydroxide (NaOH) were evaluated for the nematode response to see if these compounds can help distinguish between viable from the dead J2. Results indicated that live SCN J2 responded equally (P ≤ 0.05) to 1 μl Na2CO3 and 10 μl NaHCO3 in 100 μl of water at pH = 10. Live SCN J2 responded by twisting their bodies in a curling shape and increasing rate of movements within 2 minutes of exposure. The twisting activity continued for up to 30 minutes. Live RKN J2 responded by increasing activity with the application of 1 μl NaOH in 100 μl of water at pH = 10 also in the 2 minutes to 30 minutes time frame. Furthermore, in growth chamber tests to confirm the infectivity of live SCN. The live SCN as determined by exposure to 1 μl of Na2CO3 indicated 60.5% of the SCN J2 were alive and of those, 29.5% were infective and entered the soybean roots. The 1 μl of NaOH stimulus revealed that 75.2% RKN J2 were alive and of those, 14.9% were infective and entered soybean roots. These results confirmed that 1 μl of Na2CO3 added to 100 μl suspension of SCN J2 and 1 μl of NaOH added to 100 μl suspension of RKN J2 are the effective stimuli for rapidly distinguishing between live and dead SCN and RKN J2 in vitro. SCN and RKN J2 responded differently to different compounds.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154818PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4856281PMC
July 2017

Transcriptome Analysis of Cotton (Gossypium hirsutum L.) Genotypes That Are Susceptible, Resistant, and Hypersensitive to Reniform Nematode (Rotylenchulus reniformis).

PLoS One 2015 16;10(11):e0143261. Epub 2015 Nov 16.

Department of Biological Sciences, Auburn University, Auburn, Alabama, United States of America.

Reniform nematode is a semi-endoparasitic nematode species causing significant yield loss in numerous crops, including cotton (Gossypium hirsutum L.). An RNA-sequencing analysis was conducted to measure transcript abundance in reniform nematode susceptible (DP90 & SG747), resistant (BARBREN-713), and hypersensitive (LONREN-1) genotypes of cotton (Gossypium hirsutum L.) with and without reniform nematode infestation. Over 90 million trimmed high quality reads were assembled into 84,711 and 80, 353 transcripts using the G. arboreum and the G. raimondii genomes as references. Many transcripts were significantly differentially expressed between the three different genotypes both prior to and during nematode pathogenesis, including transcripts corresponding to the gene ontology categories of cell wall, hormone metabolism and signaling, redox reactions, secondary metabolism, transcriptional regulation, stress responses, and signaling. Further analysis revealed that a number of these differentially expressed transcripts mapped to the G. raimondii and/or the G. arboreum genomes within 1 megabase of quantitative trait loci that had previously been linked to reniform nematode resistance. Several resistance genes encoding proteins known to be strongly linked to pathogen perception and resistance, including LRR-like and NBS-LRR domain-containing proteins, were among the differentially expressed transcripts mapping near these quantitative trait loci. Further investigation is required to confirm a role for these transcripts in reniform nematode susceptibility, hypersensitivity, and/or resistance. This study presents the first systemic investigation of reniform nematode resistance-associated genes using different genotypes of cotton. The candidate reniform nematode resistance-associated genes identified in this study can serve as the basis for further functional analysis and aid in further development of reniform a nematode resistant cotton germplasm.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0143261PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4646469PMC
June 2016

Nematicides enhance growth and yield of rotylenchulus reniformis resistant cotton genotypes.

J Nematol 2014 Dec;46(4):365-75

Department of Agronomy & Soils, Auburn University, Auburn University, AL 36849-5412.

Rotylenchulus reniformis resistant LONREN-1×FM966 breeding lines developed at Auburn University have demonstrated that the nematode resistance is accompanied by severe stunting, limited growth, and low yields. The objectives of this study were to evaluate the effects of applying nematicides to selected LONREN breeding lines on R. reniformis nematode populations, plant stunting, and yield. Four resistant breeding lines from the LONREN-1×FM966 cross, one susceptible line from the LONREN-1×FM966 cross, as well as LONREN-1, BARBREN-713, and the susceptible cultivar DP393 were evaluated with and without nematicides in the presence of R. reniformis. In the greenhouse, nematicides increased plant height across all genotypes compared with no nematicide. Rotylenchulus reniformis populations were 50% lower in the resistant lines compared with the susceptible lines at 45 days after planting (DAP). In microplot and field trials, the phenotypic stunting of all genotypes was reduced by aldicarb with increases in plant heights at 30 and 75 DAP. Increases in yields were evident across all genotypes treated with aldicarb. In all three trial environments, BARBREN-713 outperformed the LONREN-derived lines as well as 'DP393' in seed cotton yields, while having significantly lower R. reniformis egg densities than the susceptible genotypes.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284089PMC
December 2014

Integrated signaling networks in plant responses to sedentary endoparasitic nematodes: a perspective.

Plant Cell Rep 2015 Jan 11;34(1):5-22. Epub 2014 Sep 11.

Department of Biological Sciences, Auburn University, 101 Rouse Life Science Building, Auburn, AL, 36849, USA.

Sedentary plant endoparasitic nematodes can cause detrimental yield losses in crop plants making the study of detailed cellular, molecular, and whole plant responses to them a subject of importance. In response to invading nematodes and nematode-secreted effectors, plant susceptibility/resistance is mainly determined by the coordination of different signaling pathways including specific plant resistance genes or proteins, plant hormone synthesis and signaling pathways, as well as reactive oxygen signals that are generated in response to nematode attack. Crosstalk between various nematode resistance-related elements can be seen as an integrated signaling network regulated by transcription factors and small RNAs at the transcriptional, posttranscriptional, and/or translational levels. Ultimately, the outcome of this highly controlled signaling network determines the host plant susceptibility/resistance to nematodes.
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http://dx.doi.org/10.1007/s00299-014-1676-6DOI Listing
January 2015

The Effect of Soil Texture and Irrigation on Rotylenchulus reniformis and Cotton.

J Nematol 2013 Jun;45(2):99-105

Syngenta Research & Development Scientist, 129 Kiowa Lane Monroe, LA 71203.

The reniform nematode, Rotylenchulus reniformis, is the most damaging nematode pathogen of cotton in Alabama. Soil texture is currently being explored as a basis for the development of economic thresholds and management zones within a field. Trials to determine the reproductive potential of R. reniformis as influenced by soil type were conducted in microplot and greenhouse settings during 2008 to 2010. Population density of R. reniformis was significantly influenced by soil texture and exhibited a general decrease with increasing median soil particle size (MSPS). As the MSPS of a soil increased from 0.04 mm in clay soil to > 0.30 mm in very fine sandy loam and sandy loam soils, R. reniformis numbers decreased. The R. reniformis population densities on all soil types were also greater with irrigation. Early season cotton development was significantly affected by increasing R. reniformis Pi, with plant shoot-weight-to-root-weight ratios increasing at low R. reniformis Pi and declining with increasing R. reniformis Pi. Plant height was increased by irrigation throughout the growing season. The results suggests that R. reniformis will reach higher population densities in soils with smaller MSPS; however, the reduction in yield or plant growth very well may be no greater than in a soil that is less preferential to the nematode.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3700743PMC
June 2013

Biocontrol of the Reniform Nematode by Bacillus firmus GB-126 and Paecilomyces lilacinus 251 on Cotton.

Plant Dis 2013 Jul;97(7):967-976

Auburn University Department of Entomology and Plant Pathology, Auburn, AL 36849.

Due to increased restrictions on the use of chemical nematicides, alternative nematode management strategies, including biocontrol, are needed. The objectives of this study were to evaluate the potential of Bacillus firmus GB-126 and Paecilomyces lilacinus 251 in commercial formulations applied separately or concomitantly to manage Rotylenchulus reniformis in cotton grown under greenhouse, microplot, and field conditions. In the greenhouse, seed treated with B. firmus (1.4 × 10 CFU/seed), an application of P. lilacinus (0.3% vol/vol of water), or the combination of B. firmus and P. lilacinus reduced the number of females, eggs, and vermiforms of R. reniformis (P ≤ 0.02) and increased populations of free-living nematodes (P ≤ 0.01). In microplots and field conditions, populations of R. reniformis vermiforms decreased when exposed to B. firmus and P. lilacinus biocontrol agents at midseason (P ≤ 0.04). Furthermore, stem diameter and free-living nematode numbers increased (P ≤ 0.01) with the combination of B. firmus and P. lilacinus. In the field, numbers of females, eggs, and vermiform life stages at the end of the growing season decreased in the presence of the biocontrol agents applied individually or concomitantly (P ≤ 0.01). Cotton yields from the application of B. firmus GB-126 and P. lilacinus 251 were similar to those from aldicarb, the chemical nematicide standard.
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http://dx.doi.org/10.1094/PDIS-10-12-0978-REDOI Listing
July 2013

A family-centered educational program to promote independence in pediatric heart transplant recipients.

Prog Transplant 2011 Mar;21(1):61-6

Children's Hospital of Pittsburgh, Pennsylvania, USA.

Context: Characteristic adolescent risk-taking behavior, including nonadherence with prescribed medications, can be life-threatening for transplant recipients. Suggestions for managing nonadherence in teen recipients include providing them and their parents with adequate information about medications, talking with and listening to pediatric recipients about problems with the comprehensive regimen, and encouraging age-appropriate responsibility for maintaining health.

Objective: The clinical goal of this project was to develop a structured age-appropriate educational program to prepare pediatric transplant recipients and their families for the patient's life as a responsible, independent individual. Our primary research goal was to assess patients' and parents' knowledge about critical aspects of heart transplantation and the treatment regimen with brief questionnaires before and after they received the educational materials from their primary nurse coordinator.

Design, Setting, Participants: This descriptive pre-post test study was done to assess the effectiveness of an innovative family-centered educational program among 20 pediatric heart transplant recipients and their parents at Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center. MAIN OUTCOME MEASURE, RESULTS: Percentage change in children's scores on questionnaires given before and after the educational intervention ranged from -8% to 300% (mean, 64.1%). Percentage change in scores from before to after for parents ranged from -19% to 53.8% (mean, 7.2%).
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http://dx.doi.org/10.7182/prtr.21.1.r257598215502271DOI Listing
March 2011

Identification of fungi associated with rotylenchulus reniformis.

J Nematol 2010 Dec;42(4):313-8

Entomology and Plant Pathology Department, 209 Life Sciences Building, Auburn University, Auburn, AL. 36849.

The objective of this work was to isolate and identify fungi associated with R. reniformis in cotton roots. Soil samples were collected in cotton fields naturally infested with R. reniformis and from cotton stock plants cultured in the greenhouse. Nematodes extracted from the soil were observed under the stereoscope, and discolored eggs and vermiform stages colonized with mycelia were cultured on 1.5% water agar supplemented with antibiotics, and incubated at 27°C. Identification of the nematophagous fungi was based on the morphological characters, and the ITS regions and 5.8S rDNA amplified by PCR using the primers ITS1 and ITS4. The parasitism percentage on vermiform nematodes from greenhouse samples was 21.2%, and the percentages from cotton fields in Limestone, Henry, and Baldwin counties in Alabama were 3%, 23.2%, and 5.6%, respectively. A total of 12 fungi were identified from R. reniformis vermiform stages and eggs. The most frequently isolated fungi were Arthrobotrys dactyloides (46%) and Paecilomyces lilacinus (14%), followed by Phoma exigua (4.8%), Penicillium waksmanii and Dactylaria brochophaga (3.6%), Aspergillus glaucus group (2.4%). Cladosporium herbarum, Cladosporium cladiosporioides, Fusarium oxysporum, Torula herbarum, Aspergillus fumigatus, and an unidentified basidiomycete were less frequent (1.2%). A high percentage (16.8%) of fungi from colonized nematodes was not cultivable on our media. Out of those 12 fungi, only four have been previously reported as nematophagous fungi: three isolates of Arthrobotrys dactyloides, and one isolate of Dactylaria brochopaga, Paecilomyces lilacinus, and Fusarium oxysporum. Molecular identification of Arthrobotrys dactyloides and Dactylaria brochopaga was consistent with the morphological identification, placing these two fungi in the new genus Drechslerella as proposed in the new Orbilaceae classification.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3380521PMC
December 2010

Natural Migration of Rotylenchulus reniformis In a No-Till Cotton System.

J Nematol 2010 Dec;42(4):307-12

Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849.

Rotylenchulus reniformis is the most damaging nematode pathogen of cotton in Alabama. It is easily introduced into cotton fields via contaminated equipment and, when present, is difficult and costly to control. A trial to monitor the natural migration of R. reniformis from an initial point of origin was established in 2007 and studied over two growing seasons in both irrigated and non-irrigated no-till cotton production systems. Vermiform females, juveniles and males reached a horizontal distance of 200 cm from the initial inoculation point, and a depth of 91 cm in the first season in both systems. Irrigation had no effect on the migration of vermiform females and juveniles, but males migrated faster in the irrigated trial than in the non-irrigated trial. Population density increased steadily in the irrigated trial during both years, exceeding the economic threshold of 1,000 per 150 cm(3), but was highly correlated with rainfall in the non-irrigated trial. The average speed of migration ranged from 0- to 3.3-cm per day over 150 days. R. reniformis was able to establish in both the irrigated and non-irrigated trials in one season and to increase population density significantly.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3380523PMC
December 2010

Using FAME analysis to compare, differentiate, and identify multiple nematode species.

J Nematol 2009 Sep;41(3):163-73

Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA.

We have adapted the Sherlock(®) Microbial Identification system for identification of plant parasitic nematodes based on their fatty acid profiles. Fatty acid profiles of 12 separate plant parasitic nematode species have been determined using this system. Additionally, separate profiles have been developed for Rotylenchulus reniformis and Meloidogyne incognita based on their host plant, four species and three races within the Meloidogyne genus, and three life stages of Heterodera glycines. Statistically, 85% of these profiles can be delimited from one another; the specific comparisons between the cyst and vermiform stages of H. glycines, M. hapla and M. arenaria, and M. arenaria and M. javanica cannot be segregated using canonical analysis. By incorporating each of these fatty acid profiles into the Sherlock(®) Analysis Software, 20 library entries were created. While there was some similarity among profiles, all entries correctly identified the proper organism to genus, species, race, life stage, and host at greater than 86% accuracy. The remaining 14% were correctly identified to genus, although species and race may not be correct due to the underlying variables of host or life stage. These results are promising and indicate that this library could be used for diagnostics labs to increase response time.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3380492PMC
September 2009

Safety and immunogenicity of the American Academy of Pediatrics--recommended sequential pneumococcal conjugate and polysaccharide vaccine schedule in pediatric solid organ transplant recipients.

Pediatrics 2005 Jul;116(1):160-7

Department of Pediatrics, Children's Hospital of Pittsburgh, PA 15213, USA.

Objective: Solid organ transplant recipients are at increased risk for invasive pneumococcal disease. The American Academy of Pediatrics recommends immunization with sequential pneumococcal vaccines for this group; however, data are lacking. Accordingly, this study was designed to evaluate the safety and immunogenicity of the recommended regimen.

Methods: Pediatric solid organ transplant recipients (n = 25) between 2 and 18 years of age who had not previously received 7-valent conjugate pneumococcal vaccine (PCV7) were enrolled. These patients received 2 doses of the PCV7 and a single dose of the 23-valent polysaccharide pneumococcal vaccine (23V). Each vaccine dose was given 2 months apart. Healthy age-matched controls (n = 23) were enrolled for comparison. Controls received a single dose of PCV7 followed 2 months later by a single dose of 23V. Antibody concentrations to serotypes 1, 4, 5, 6B, 9V, 14, 18C, 19F, and 23F were measured by enzyme-linked immunosorbent assay prevaccination, 2 months after each vaccine dose and 5 to 7 months after 23V. Local and systemic reactions to each vaccine dose were recorded.

Results: Systemic and injection-site reactions were comparable between the 2 groups. Significant rises in serotype-specific pneumococcal antibody geometric mean concentrations from prevaccination levels were observed in both groups; however, final antibody responses to serotypes 1, 4, 9V, 14, 18C, 19F, and 23F were significantly lower in solid organ transplant recipients compared with the control group. Antibody concentrations did not increase significantly among solid organ transplant patients after the second dose of PCV7. No additional increase in PCV7-associated serotype-specific antibody levels was observed after the 23V dose in both groups. Heart transplant recipients had lower antibody responses compared with liver transplant recipients.

Conclusions: Although the pneumococcal vaccine regimen was safe and immunogenic among pediatric solid organ transplant recipients, the patients did not seem to benefit from the second dose of PCV7 or from the 23V dose given 2 months later. Additional studies are needed to determine the number of PCV7 doses and the interval between PCV7 and 23V to induce optimal responses.
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http://dx.doi.org/10.1542/peds.2004-2312DOI Listing
July 2005