SUMMARY Some plant endoparasitic nematodes are biotrophic and induce remarkable changes in their hosts in order to ensure a continuous supply of food. Proteins secreted from oesophageal gland cells have been implicated in this pathogenic process. A potentially secreted chorismate mutase has been isolated from the potato cyst nematode Globodera pallida. The gene encoding this protein is expressed in the subventral oesophageal gland cells of the nematode, and the mRNA derived from this gene is only present in the early parasitic stages. Sequence analysis of this gene shows that, like other genes involved in the host-parasite interaction of plant parasitic nematodes, it is likely to have been acquired by horizontal gene transfer from bacteria. The presence of a signal peptide in the deduced amino acid sequence of the G. pallida chorismate mutase and its expression in the subventral oesophageal gland cells suggest that it is secreted from the nematode, pointing to a role for the protein in the host-parasite interaction. The shikimate pathway, of which chorismate mutase is normally a part, is not found in animals but is present in plants and bacteria. In plants it gives rise to a variety of compounds which are important in amino acid synthesis and defence signalling pathways, as well as auxins, which have been implicated in the early development of nematode feeding sites. The potential roles of a nematode chorismate mutase are discussed.

Objetivou-se estudar o efeito nematicida de manipueira no controle de Meloidogyne incognita. Testes in vitro foram divididos em dois ensaios inteiramente casualizados: 1. manipueira a 100%, 75%, 50% e 25% em 12 repetições; 2. manipueira a 15%, 10%, 8%, 6%, 4% e 2% em 5 repetições. O ensaio em vasos seguiu o delineamento inteiramente casualisado com manipueira a 10%, 25% e 50% em 5 repetições. Para ambos os ensaios utilizou-se o tratamento somente água como testemunha positiva e Carbofuran (50 mg.L-1 de ingrediente ativo (i.a.) ou 2 g de produto comercial/vaso) como negativa. Para os ensaios in vitro foram avaliados nematóides vivos e mortos e número de galhas em plantas inoculadas. Para os ensaios em vaso foram avaliadas as variáveis altura de plantas, comprimento de raízes, número de galhas, número de ovos e fator de reprodução (FR). Os resultados in vitro demonstraram que os tratamentos com manipueira até 10% de diluição apresentaram 100% de controle. O ensaio com tomateiros previamente inoculados demonstrou que o tratamento manipueira 50% causou um melhor desenvolvimento da parte aérea das plantas de tomate. Os tratamentos manipueira a 10% e 25% foram mais efetivos no controle de M. incognita em vasos.

Meloidogyne incognita is one of the most polyphagous species of root-knot nematodes occurring in Brazil and worldwide. Eight M. incognita isolates were studied, representing two enzymatic phenotypes (esterase and malate desydrogenase: I1/N1, I2/N1) and four cryptic Meloidogyne sp.1 (S2/N1) isolates, representing one cytological type (3n040-46). Three M. hispanica isolates (Hi3/N1, 2n032-36) and two of an atypical Meloidogyne sp.2 (S2a/N3, 3n040-44) were included in this study for comparison. All isolates were tested with three M. incognita-specific molecular markers. The primer pairs B06F/R, miF/R and incK14F/R amplified three species-specific fragments of 1,200 bp, 955 bp and 399 bp, respectively for M. incognita and Meloidogyne sp.1 isolates. No amplification occurred in the M. hispanica and Meloidogyne sp.2 isolates, except with primers miF/R (1,650 bp). The genetic variability of the Meloidogyne spp. isolates was evaluated, using RAPD and ISSR markers. The phylogenetic analyses revealed two strongly supported monophyletic clades: clade I, consisting of M. hispanica and the atypical Meloidogyne sp.2 isolates, and clade II, clustering together all M. incognita and the Meloidogyne sp.1 isolates. Considering the biometrical, cytological and molecular approaches, it was possible to conclude that the isolates with three enzymatic phenotypes (I1/N1, I2/N1 and S2/N1) presented the characteristics described for M. incognita. Some correlations were detected between the isozymatic phenotypes and the tree topology (S2a/N3, Hi3/N1, I1/N1, S2/N1), but no strict correlation could be observed for the phenotype I2/N1 and one isolate of S2/N1. Morphologically, the Msp.2 isolates differ from M. incognita and M.

Root-knot nematodes (RKN), Meloidogyne spp., have major economic impact on coffee production in Central and South America. Genetic control of RKN constitutes an essential part for integrated pest management strategy. The objective of this study was to evaluate the resistance of Coffea canephora genotypes (clones) to Meloidogyne spp. Sensitive and drought-tolerant coffee genotypes were used to infer their resistance using nematode reproduction factor and histopathology. Eight clonal genotypes were highly resistant to M. paranaensis. 'Clone 14' (drought-tolerant) and 'ESN2010-04' were the only genotypes highly resistant and moderately resistant, respectively, to both M. incognita races 3 and 1. Several clones were highly resistant to both avirulent and virulent M. exigua. Clone 14 and ESN2010-04 showed multiple resistance to major RKNs tested. Roots of 'clone 14' (resistant) and 'clone 22' (susceptible) were histologically studied against infection by M. incognita race 3 and M. paranaensis. Reduction of juvenile (J2) penetration in clone 14 was first seen at 2 to 6 days after inoculation (DAI). Apparent early hypersensitive reaction (HR) was seen in root cortex between 4 and 6 DAI, which led to cell death and prevention of some nematode development. At 12 to 20 DAI, giant cells formed in the vascular cylinder, besides normal development into J3/J4. From 32 to 45 DAI, giant cells were completely degenerated. Late, intense HR and cell death were frequently observed around young females and giant cells reported for the first time in coffee pathosystem. These results provide rational bases for future studies, including prospection, characterization, and expression profiling of genomic loci involved in both drought tolerance and resistance to multiple RKN species.

Flavonoids have diverse roles in plants, including defence against plant pathogens and regulation of local auxin transport. Flavonoids have been shown to be produced in feeding sites of root-knot nematodes induced in a leguminous plant, and it has previously been suggested that they may be responsible for manipulation of local auxin levels that underlie early feeding site development. Here we show that flavonoids are also produced in developing syncytia induced by Heterodera schachtii and in galls induced by Xiphinema diversicaudatum in a non-leguminous plant, Arabidopsis thaliana. We further investigated whether flavonoids are required for normal feeding site development by screening mutant lines of A. thaliana, defective in various parts of the flavonoid biosynthetic pathway, with H. schachtii. None of the lines showed a reduced capacity to support nematode infection and some showed a statistically significant increase in the numbers of female nematodes that developed. These data suggest that flavonoids are produced as part of the defence response to nematode infection rather than being an integral component of the mechanisms used by nematodes to induce feeding sites.

RESUMO - PLANT PARASITIC NEMATODES ASSOCIATED WITH FRUIT CROPS IN THE NORTHWEST OF PARANÁ, BRAZILABSTRACT -A survey was carried out in order to study the occurrence of plant parasitic nematodes in fruit crops in the Northwest of Paraná, from December 2007 to February 2009. A hundred and twenty four soil and roots samples were collected from 19 species of fruit crops in 15 different municipalities. Nematodes were extracted from the samples and identified under an optical microscope. Nine genera of plant parasitic nematodes were found. In citrus, the most abundant species was Tylenchulus semipenetrans, but it was also recovered Meloidogyne, Pratylenchus, Helicotylenchus, Xiphinema, Trichodorus, Mesocriconema and Dolichodorus. In the other fruit crops, Meloidogyne, Pratylenchus, Helicotylenchus and Hemicycliophora were recovered. Pratylenchus brachyurus was the most abundant in pineapple crops, Meloidogyne incognita in fig and persimmon, and Helicotylenchus dihystera and H. multicinctus in banana. The main plant parasitic nematode genera were found in approximately 50% of the samples collected, which may represent a possible threat to regional fruit production if not managed adequately.

Phylogenetic studies have shown that parasitism of plants by nematodes has arisen independently on at least three separate occasions. We argue that horizontal gene transfer has played a critical role in the evolution of plant parasitism on each occasion. In addition, we discuss evidence that suggests this process has driven the evolution of other life strategies within the Nematoda and that it may be considerably more common within the Phylum than commonly thought. We review recent literature that shows horizontal gene transfer to nematodes has occurred from both bacteria and fungi. Molecular biology has enabled the details of many aspects of nematode biology and of host-parasite interactions to be analysed at a far deeper level than would once have been thought possible. One of the most useful applications of these techniques has been the development of a detailed and accurate phylogeny for the Phylum Nematoda. As any nematologist will testify, classifying nematodes on the basis of morphology alone is extremely difficult. At one level, attempting to confirm the species identity of, for example, a root-knot nematode sample may require a skilled taxonomist equipped with a top quality microscope. At another level, attempting to interpret the deeper phylogenetic relationships across the Phylum is made difficult by the relatively conserved body plan of many nematodes and by the absence of a fossil record that would allow evolution of nematodes to be studied. The problems encountered working at either of these levels have been addressed by analysis and comparisons of the small subunit ribosomal DNA sequences of nematodes from across the Phylum (Blaxter et al., 1998). This work, and other similar projects that have followed (Beckenbach et al., 1999;Blaxter et al., 2000), have enabled a detailed phylogeny of nematodes to be drawn up and the interrelationships of the major nematode groups to be established.

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