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author:("agudo, Paula")
1.  Induction of Glutaredoxin Expression in Response to Desiccation Stress in the Foliar Nematode Aphelenchoides fragariae 
Journal of Nematology  2012;44(4):370-376.
Desiccation tolerance plays an important role in the overwinter survival of the foliar nematode Aphelenchoides fragariae. Survival rates of A. fragariae were compared with those of the anhydrobiotic soil-dwelling nematode Aphelenchus avenae after desiccation (90% RH), cold (4°C) and osmotic (500 mM sucrose) stress treatments. A. fragariae formed aggregates during desiccation and showed higher survival rates than A. avenae under desiccation and osmotic stress. Analysis of transcripts with Illumina RNA-seq indicated that glutaredoxin and other antioxidant-related genes were up-regulated under desiccation stress. Quantitative RT-PCR demonstrated 2.8 fold and 1.3 fold up-regulation of a glutaredoxin gene under desiccated and osmotic stress, respectively, suggesting the participation of antioxidant mechanisms in desiccation tolerance of A. fragariae.
PMCID: PMC3592362  PMID: 23483835
Aphelenchoides fragariae; desiccation; cold stress; osmotic stress; glutaredoxin; survival rate
2.  Molecular Characterization and Phylogenetic Analysis of Hoplolaimus stephanus 
Journal of Nematology  2011;43(1):25-34.
Three Hoplolaimus stephanus populations were characterized morphologically, both by morphometrics and by SEM observations. These populations were used to develop a rapid and accurate molecular identification method for the species, which is useful because of the high level of morphological similarity between H. stephanus and H. galeatus. Species-specific primers for H. stephanus, amplifying a distinct fragment (260 bp) of the nuclear ribosomal internal transcribed spacer1 (ITS1), can be used in multiplex PCR along with previously developed primers for other common Hoplolaimus species. We also infer phylogenetic relationships among H. stephanus, the closely-related H. galeatus, and several other Hoplolaimus species, using sequences of the actin gene, ITS1 and LSUD.
PMCID: PMC3380482  PMID: 22791912
actin; DNA taxonomy; Hoplolaimidae; Hoplolaimus stephanus, lance nematodes; plant-parasitic nematodes
3.  Using FAME Analysis to Compare, Differentiate, and Identify Multiple Nematode Species 
Journal of Nematology  2009;41(3):163-173.
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.
PMCID: PMC3380492  PMID: 22736811
biochemistry; FAME analysis; identification; Meloidogyne spp.; Meloidogyne arenaria; Meloidogyne hapla; Meloidogyne incognita; Meloidogyne javanica; Rotylenchulus reniformis; Heterodera glycines
4.  Effect of Temperature on the Embryogenesis of Geographic Populations of Rotylenchulus reniformis 
Journal of Nematology  2009;41(1):23-27.
The effect of temperature on the embryonic development of three populations of reniform nematode (Rotylenchulus reniformis) from the southeastern United States was studied. The development of eggs from single-cell stage to eclosion of second-stage juvenile was monitored at 20, 25, 30, and 35°C. All populations completed embryogenesis in 7 days at 25°C. The greatest differences among populations in time to completion of embryogenesis were observed at 20 and 35°C. Results at the intermediate temperatures (25 and 30°C) were similar for the three populations. The optimal temperature for embryogenesis was calculated to be 31.4°C for the population from Alabama, 28.4°C for the one from Mississippi, and 37.5°C for the one from South Carolina.
PMCID: PMC3365293  PMID: 22661774
embryogenesis; Rotylenchulus reniformis; reniform nematode; temperature
5.  Histological Observations of Rotylenchulus reniformis on Gossypium longicalyx and Interspecific Cotton Hybrids 
Journal of Nematology  2005;37(4):444-447.
Observations on the development of reniform nematode (Rotylenchulus reniformis) on roots of Gossypium longicalyx, G. hirsutum, and two interspecific hybrids derived from them were made by light microscopy. Gossypium longicalyx is reported to be immune to reniform nematode, but the mechanism(s) for resistance are unknown. Penetration of G. longicalyx roots by female nematodes was confirmed, and incipient swelling of the females, indicating initiation of maturation of the reproductive system, was observed. Female maturation occurred up to the formation of a single embryo inside the female body but not beyond this point. In both hybrids, development was inhibited but progressed further than in the immune parent. Reactions ranged from highly compatible, with the formation of active syncytia and full development of females, to incompatible with little or no development of the female. Compatible plants showed characteristic hypertrophied cells, enlarged nuclei, dense cytoplasm, and partial dissolution of cell walls, whereas incompatible plant reactions included lignification of the cells adjacent to the nematode head, or the complete collapse and necrosis of the cells involved. The need to characterize reactions and to carefully select among the plants descended from the hybrids during the introgression process, as well as the importance of combining the results of reproduction tests with histological observation of the plant-nematode interactions, is discussed.
PMCID: PMC2620996  PMID: 19262889
cotton; Gossypium hirsutum; Gossypium longicalyx; histopathology; reniform nematode; resistance; Rotylenchulus reniformis
6.  Histological Changes in Gossypium hirsutum Associated with Reduced Reproduction of Rotylenchulus reniformis 
Journal of Nematology  2005;37(2):185-189.
The reniform nematode (Rotylenchulus reniformis) is an important parasite of upland cotton (Gossypium hirsutum). Parasitism involves the formation of syncytia to provide nutrition for the female. Events that occur at the feeding site may determine the degree of susceptibility of cotton plants to reniform nematode. The objective of this work was to describe histological modifications associated with reduced reproduction of Rotylenchulus reniformis in upland cotton roots. 'Deltapine 50' cotton and a selection from this line with a moderate level of resistance were inoculated with reniform nematode in the greenhouse, and observations on roots were made 3, 6, 9, 12, and 15 days after inoculation. No differences in penetration behavior or in the formation and characteristics of syncytia were observed. Reduced reproduction was correlated with an earlier degeneration and collapse of the syncytial cells, and occasionally, with lack of hypertrophy of the pericycle cells involved. These two mechanisms accounted for 40% to 60% reduction of reproduction of reniform nematode in the plants examined.
PMCID: PMC2620962  PMID: 19262859
cotton; Gossypium hirsutum; histopathology; reniform nematode; reproductive index; resistance; Rotylenchulus reniformis
7.  Intraspecific Variability of Rotylenchulus reniformis from Cotton-growing Regions in the United States 
Journal of Nematology  2005;37(1):105-114.
Reniform nematode (Rotylenchulus reniformis) is a major pest of cotton in the southeastern United States. The objective of this study was to examine the variation of reniform nematode populations from cotton-growing locations in the United States where it is prevalent. Multivariate analysis of variance and discriminant analysis were used to determine the variability of morphology in males and immature females. Reproduction indices of populations were measured on selected soybean and cotton genotypes in the greenhouse. High variability in morphometrics and reproduction was observed within all the populations, and several differences were found among populations. DNA sequences of the nuclear ribosomal first internal transcribed spacer region (ITS1) were compared among populations from the United States and to sequences of populations from Brazil, Colombia, Honduras, and Japan. No polymorphic nucleotide sites were observed among the amphimictic populations. Only a parthenogenic population from Japan was distinct. The phenotypic polymorphism of the species in the United States could impact the effectiveness of management strategies based on host plant resistance.
PMCID: PMC2620946  PMID: 19262849
cotton; genetic variation; morphometrics; reniform nematode; reproductive index; ribosomal DNA; Rotylenchulus reniformis

Results 1-7 (7)