Morphologically similarAphelenchoidesspp. populations extracted from rice and forage grass seeds from different geographical regions in Brazil were morphologically and molecularly characterised. Overall, the populations studied separated into two groups based on morphological and phylogenetic analyses, referred to herein as ‘Group-rice’ and ‘Group-forage’. Bayesian phylogenetic analyses of SSU, LSU and mtCOI regions strongly supported the presence of two dichotomous groups with Group-rice and Group-forage populations genetically similar toA. besseyiandA. fujianensis, respectively. This study reports the presence of a morphologically similar species toA. besseyiassociated with seeds of grasses, but genetically distinct based on three genomic regions, which our results strongly suggest to beA. fujianensis, this being a new geographical record for Brazil. Additional information regarding spicule morphology of maleA. besseyiis also reported.

The influence of parasitic nematodes on okra crop in eastern Minas Gerais State, BrazilOkra has a cultural and social importance for the State of Minas Gerais (MG), and 34,2% of the volume marketed in the Ceasa/ Contagem, MG, come from the municipalities located near Caratinga and Governador Valadares. The okra production is influenced for the infection caused by the root-knot nematodes (Meloidogyne spp.). The main species of these nematodes attacking okra have already been reported in Brazil, and some of them can cause plant death. The correct identification of Meloidogyne species and, or races infecting okra roots is mandatory for choosing appropriate control measures. To determine the occurrence and distribution of Meloidogyne spp. and other nematodes in the area of the East of MG, 70 soil and root samples coming from 14 municipalities were appraised for morphological and isoenzymatic characteristics. Among the populations of Meloidogyne spp., M. incognita (Esterase phenotypes I1 and I2) prevailed and were followed by M. javanica (phenotypes J2 and J3) and M. arenaria (phenotypes A2). The species M. mayaguensis was confirmed by the phenotypes: esterase (M2), malate dehydrogenase (N3), superoxide dismutase (N2) and glutamate oxaloacetate transaminase (N3). This is the first report of the M. mayaguensis occurrence in MG. Other nematodes associated with the okra plants were Aphelenchus sp., Criconemella sp., Helicotylenchus spp., Pratylenchus brachyurus and P. coffeae, Rotylenchulus reniformis, Rotylenchus sp., Tylenchus sp. and Tylenchorhynchus sp.

No abstract

Aphelenchoides besseyi and A. fujianensis have been frequently found in mixed populations associated with forage grass seed in Brazil. The morphological similarity between both species has previously led A. fujianensis to be erroneously identified as A. besseyi. A. besseyi is a quarantine pest in many countries that import Brazilian forage seed; however, there is no current evidence suggesting that A. fujianensis is a plant-parasitic species. Two real-time polymerase chain reaction (qPCR) diagnostics were developed to detect each species and an operational envelope was established. A set of primers and hydrolysis probes for each species was designed targeting the large subunit (LSU) region. To assess their specificity, primers and probes sets were tested with samples of nontarget Aphelenchoides and Paraphelenchus sp. also frequently associated with forage seed. Experiments using dilutions of purified plasmid standards underpinned the sensitivity of the qPCR assays, which detected as few as 10 copies of target nematode ribosomal DNA. Thus, the developed diagnostics were sufficiently sensitive to detect DNA extracted from a fragment of a single target nematode. There was a positive correlation between copy number of the target species and nematode abundance, suggesting the potential of this method for quantification. Evidence of intra-individual variability among cloned sequences of the LSU region in a single A. besseyi population is also reported.

ResumoHeterodera glycines é um fitonematoide de importância econômica para a cultura da soja. Por isso, objetivou-se comparar metodologias para a avaliação de genótipos de soja em relação a este nematoide. Evaluation of soybean genotypes in relation to the cyst nematode AbstractHeterodera glycines is a phytonematode of economic importance in the soybean crop. Therefore, the objective was to compare methodologies for evaluation of soybean genotypes in relation to H. glycines. Two experiments were conducted (trials A and B) under greenhouse condition in a completely randomized design with six replications. In the trial A, ceramic pots of 0.8 dm 3 and standard methodologies of inoculation and assessment were used. In the trial B, polyethylene pots filled with 0.5 dm 3 infested soil and visual analysis were used. Promising genotypes obtained by different soybean genetic breeding programs were evaluated. Seventy four percent of the studied genotypes presented similar numbers of females in both trials. The correlation coefficient between the number of female in trial A and the number of female in trial B was 0.85 (p<0.01) and between the number of female in trial A and the visual rating of the number of females in trial B was 0.90 (p<0.01). The standard methodologies of inoculation and evaluation using infested soil and visual analysis were, in general, mutually consistent. Genotypes identified as resistant (UFVS 2010 and BCR1070G229) and moderately resistant (BCR132390, BCR945G114 and BCR1057G163) to the cyst nematode race 3 were found by the two methods of assessment.