Alterações anatômicas induzidas por Meloidogyne enterolobii (=M. mayaguensis) e Meloidogyne javanica em tomateiros resistentes a meloidoginose

Abstract

The resistance of tomato plants (Solanum Lycopersicum L.) to M. incognita, M. javanica and M. arenaria, provided by the presence of Mi gene, does not include the species M. enterolobii (=M. mayaguensis). The aim of this study was to verify the anatomical changes caused by M. enterolobii in the root system of rootstocks from tomato plants with Mi resistance gene ('Magnet' and 'Helper M') and to compare these changes with those caused by M. javanica . The anatomical observations of roots were done with the aid of a light microscope and the most relevant aspects were photographed. Based on counts and measurements of the size of feeding sites and giant cells, the data Westerich, J.N.; Rodella, R.A.; Rosa, J.M.O.; Wilcken, S.R.S. Anatomical Changes Induced by Meloidogyne enterolobii (=M. mayaguensis) and Meloidogyne javanica in Tomato Plants Resistant to the Root-Knot Nematode. Summa Phytopathologica, v.38, n.3, p.192-197, 2012. were analyzed by using the statistical method of Cluster Analysis. The emergence of nurse cells stimulated by M. enterolobii was observed for both tomato rootstocks between 10 and 17 days after inoculation (DAI). The number and the area of feeding sites and giant cells were smaller at 17 DAI than at 24 DAI. On the latter occasion (24 DAI), there were feeding sites established by the presence of several multinucleate nurse cells with thick cell walls and dense and granular cytoplasm. Vascular tissues were compressed and disorganized; there was also hypertrophy of cortical parenchyma cells. Roots inoculated with M. javanica did not show anatomical changes. v.38, n.3, p.192-197, 2012. Análise de Agrupamento. O aparecimento de células nutridoras incitadas por M. enterolobii foi verificado em ambos os porta-enxertos de tomateiro, entre 10 e 17 dias após a inoculação (DAI). O número e a área de sítios de alimentação e de células gigantes foram menores aos 17 DAI do que aos 24 DAI. Nesta época (24 DAI), foram observados sítios de alimentação constituídos pela presença de várias células nutridoras multinucleadas, com parede celular espessa, citoplasma denso e granuloso. Os tecidos vasculares apresentaram-se comprimidos e desorganizados, foi observada, também, hipertrofia de células do parênquima cortical. As raízes inoculadas com M. javanica não apresentaram alterações anatômicas.

Structure and development of root gall induced by Meloidogyne javanica in Glycine max L.

“…In a study of galls induced by M. javanica in rubber trees, giant cells were found in the vascular cylinder at 20 DAI (FONSECA et al, 2003). Here, galls induced by M. javanica showed giant cells at 18 DAI, similar that found by Westerich et al (2012), where giant cells were found in galls induced by M. enterolobii on roots of tomatoes after 17 DAI. In general, giant cells are formed between 18 and 20 DAI, regardless of the host species or the inducer Meloidogyne species.…”

“…We also noted the proliferation of the Golgi apparatus, plastids, ribosomes and endoplasmic reticulum in the giant cells, as previously reported by Vieira et al (2013), Berg et al (2008), Sobczak and Golinowski (2011). In the induced giant cells, single large central vacuoles were replaced with several smaller ones, as reported by Bird (1961), Davis et al (2004) and Abad et al (2009), by Westerich et al (2012) in tomato roots inoculated with M. enterolobii, and by Fonseca et al (2003) in rubber trees infected by M. javanica. The induction and maintenance of giant cells depend on continuous stimuli from the nematodes, without which the cells atrophy.…”