ResumoQuarenta e sete acessos de Psidium spp. foram avaliados em casa de vegetação quanto à resistência a M. enterolobii, visando ao desenvolvimento de porta-enxertos e cultivares resistentes. Cinco a sete mudas de cada acesso foram produzidas por propagação vegetativa ou a partir de sementes e, no estádio de quatro pares de folhas, foram submetidas à inoculação com 500 ovos desse nematoide. Cento e trinta e cinco dias após, extraiu-se metade do sistema radicular das plantas (cortado ao longo de seu eixo longitudinal) para extração de ovos. As mudas foram replantadas com as raízes restantes e mantidas vivas em casa de vegetação. As contagens de ovos foram feitas em três alíquotas de 1 mL/planta, e multiplicadas por dois para obtenção da população final (Pf). As Pf's de todas as alíquotas foram submetidas a ANOVA, a qual indicou diferenças significativas (p<0,01) entre acesssos e entre plantas de mesmo acesso. A classificação dos acessos quanto à resistência foi feita pelo fator de reprodução (FR=Pf/500). Todas as plantas do araçazeiro (P. cattleyanum) (acessos 115 e 116) foram resistentes (FR<1) a M. enterolobii, enquanto que em outros araçás e goiabas houve um número variável de indivíduos com FR abaixo ou pouco acima de 1. Estas plantas serão multiplicadas vegetativamente e reavaliadas quanto à resistência a M. enterolobii.Palavras-chave: nematoide de galhas, declínio da goiabeira, goiaba, araçá. Assessment of Psidium spp. accessions for resistance to Meloidogyne enterolobiiAbstract Forty-seven accessions of Psidium spp. were evaluated under greenhouse conditions for resistance to M. enterolobii, as part of an effort to develop resistant rootstocks and cultivars. For each accession, five to seven plants were produced from stem cuttings or from true seeds and, at the stage of four pairs of leaves, they were inoculated with 500 nematode eggs. One hundred and thirty-five days later, the plants were removed from the pots and half of root system was processed for extraction of eggs. The plants were replanted with the remaining roots. The egg counts, obtained from three 1 mL aliquots per plant, were multiplied by two to obtain the final nematode population (Pf). The Pf values of all aliquots were submitted to ANOVA, which revealed significant differences among accessions and among plants of the same accession. The plants were classified as resistant or susceptible based on the reproduction factor (RF = Pf/500). All plants of cattley guava (P. cattleyanum) (accessions 115 and 116) were resistant (RF <1) to M. enterolobii, while other Psidium spp. presented some plants with RF below or just above 1. These plants will be propagated and reassessed for resistance to M. enterolobii.

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The term phytotelma (pl. phytotelmata) designates a plant-associated reservoir of fresh water and organic debris. Phytotelmata in tank bromeliads are abundant in tropical forests, and they provide shelter, food, and water for many metazoans. Among the invertebrates known to inhabit phytotelmata, nematodes are the least studied, despite their important role in nutrient and energy cycles in freshwater ecosystems. This study was conceived to characterize the nematode trophic structure in the phytotelma of the bromeliad N. cruenta, and to identify climate and microenvironmental variables that impact it. Nematode abundance (total and per trophic group), rainfall, air temperature, the amount of organic debris fallen into the phytotelma, and eight physico-chemical properties (PCPs) of the water retained in the bromeliad tank-volume; temperature; pH; dissolved organic carbon, nitrogen, oxygen, and solids; and electrical conductivity-were monitored during two years in a natural reserve in Brazil. Bacterial and hyphal feeder nematodes predominated over other trophic groups. Nematode abundance (total and per trophic group) was not impacted by fluctuations in rainfall or air temperature. The amount of organic debris fallen into the phytotelma correlated positively with nematode abundance (total and per trophic group). Regarding the PCPs of water, the only significant correlationpositive-was between the amount of dissolved oxygen and the abundance of hyphal feeder nematodes. These results bring a clearer understanding of the ecology of nematodes inhabiting phytotelmata, which are peculiar and understudied freshwater ecosystems.

Guava decline, caused by the interaction between the phytonematode Meloidogyne enterolobii and the fungus Fusarium solani, has caused direct and indirect losses to the whole productive chain of guava. Aiming to understand the interaction mechanisms between M. enterolobii and F. solani, this study carried out a bioassay on guava plants with roots in two different treatments: inoculated separatelyor together with the fungus and/or nematode. The nematode parasitism not triggered an systemic effect on the plant become susceptible to root rot caused by the fungus.Therefore, it was concluded that there was a local effect of parasitism by M. enterolobii on the pathogenicity of F. solani in guava roots, making it necessary for the two pathogens to occupy the same space at the same time for occurrence of guava decline.Keywords: complex disease, Fusarium solani, guava root-knot nematode, Meloidogyne enterolobii, Psidium guajava. Cite asGomes VM, Souza RM, Almeida AM, Dolinski C. Relationships between M. enterolobii and F. solani: spatial and temporal dynamics in the occurrence of guava decline. Nematoda. 2014;1:e01014. http://dx

The alarming increase in bacterial resistance to antibiotics has demanded new strategies for microbial inactivation, which include photodynamic therapy whose activity relies on the photoreaction damage to the microorganism membrane. Herein, the binding mechanisms of the photosensitizer toluidine blue-O (TBO) on simplified models of bacterial membrane with Langmuir monolayers of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and 1,2dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (DOPG) were correlated to the effects of the photoinduced lipid oxidation. Langmuir monolayers of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) were also used as a reference of mammalian membranes. The surface pressure isotherms combined with polarization-modulated infrared reflection absorption spectroscopy revealed that TBO expands DOPC, DOPE, and DOPG monolayers owing to electrostatic interactions with the negatively charged groups in the phospholipids, with a stronger adsorption on DOPG, which has a net surface charge. Light irradiation made the TBO-containing DOPC and DOPE monolayers less unstable as a result of the singlet oxygen ( 1 O 2 ) reaction with the chain unsaturation and hydroperoxide formation. In contrast, the decreased stability of the irradiated TBO-containing DOPG monolayer suggests the cleavage of carbon chains. The anionic nature of DOPG allowed a deeper penetration of TBO into the chain region, favoring contact-dependent reactions between the excited triplet state of TBO and lipid unsaturations or/and hydroperoxide groups, which is the key for the cleavage reactions and further membrane permeabilization.

In an effort to devise a biological strategy to control guava decline, 120 rhizobacteria isolates were obtained from symptomless guava trees located in Meloidogyne enterolobii-infested orchards. Of those isolates, 44 were assessed for their potential to reduce nematode's reproduction: for each isolate, six guava stem cuttings were embedded for eight hours with bacterial suspension and transplanted. Upon development of the roots, the plants were inoculated with 2000 nematode eggs and allowed to grow for four months under greenhouse. Seedlings embedded with water, inoculated or not with the nematode, served as controls. All treatments were equivalent in the five variables that assessed plant development. Several rhizobacteria reduced (p<0.05) the final nematode population (Fp), Fp/gram of root and reproduction factor, although not to satisfactory levels. Subsequently, a two-year experiment was set up in a guava orchard affected by guava decline, in which three of the most effective rhizobacterial isolates were compared with the biological products Nemat ® and Nemaplus ® for their ability to reduce variables related to nematode parasitism and increase guava productivity. Seven bimonthly applications of these treatments under the tree canopy were unable to reduce nematode parasitism and increase productivity. The decline and death of some plants forced the experiment to be stopped after the first harvest. In conclusion, rhizobacteria applications seem unable to reduce the parasitism of M. enterolobii on guava plants, and even less to reduce the extensive root decay or alleviate the physiological stress suffered by trees affected by guava decline.Key words: Psidium guajava, Meloidogyne enterolobii, biological control, Fusarium solani.Avaliação de rizobactérias em casa de vegetação e em campo visando ao controle do declínio da goiabeira ResumoBuscando o controle biológico do declínio da goiabeira, foram obtidos 120 isolados de rizobactérias de goiabeiras assintomáticas, localizadas em pomares infestados por M. enterolobii. Dos 120 isolados, 44 foram avaliados em seu potencial para reduzir o nível populacional do nematoide. Para cada isolado, seis estacas vegetativas de goiabeira foram embebidas com suspensão bacteriana por 8 horas e transplantadas para sacolas de 5 L. Após o desenvolvimento das raízes, as mudas foram submetidas à inoculação com 2.000 ovos de M. enterolobii e mantidas por quatro meses em casa de vegetação. Mudas submetidas à inoculação com água, com ou sem M. enterolobii, serviram como controles. Os 46 tratamentos foram equivalentes nas cinco variáveis que avaliaram o desenvolvimento das plantas. Várias rizobactérias reduziram (p<0,05) a população final do nematoide (PF), PF/g de raiz e fator de reprodução, embora em níveis insatisfatórios. Posteriormente, um experimento bianual foi estabelecido em um pomar afetado pelo declínio da goiabeira, no qual três rizobactérias foram comparadas com os produtos biológicos Nemat ® e Nemaplus ® em sua capacidade de reduzir o parasitismo pelo nematoide e au...