Publications

3807

El Huanglongbing representa un gran reto para su control, por lo que se requiere de alternativas efectivas a la aplicación de insecticidas al insecto vector. La inducción de resistencia sistémica es una alternativa para disminuir el progreso de la enfermedad en árboles infectados. El objetivo de este trabajo fue evaluar el efecto de inductores de resistencia sistémica sobre la concentración de <em>?Candidatus</em> Liberibacter asiaticus? (CLas) en árboles de limón mexicano (Lm) en condiciones de invernadero. Los inductores de resistencia utilizados fueron ácido salicílico (T1), <em>Azospirillum brasilense</em> Cd (T2) y quitosano (T3), aplicados cada 20 días durante ocho meses. La cuantificación de CLas fue mediante qPCR. La concentración de CLas se determinó a los 1, 2, 5 y 8 meses pos-tratamiento. A los 8 meses pos-tratamiento, T1 y T3 no presentaron diferencias postratamiento en la reducción postratamiento de la concentración de CLas con respecto al control sin inductor (T4) (6.5×103 células bacterianas/100 ng de ADN), mientras que T2 disminuyó casi tres veces la concentración de CLas con respecto al control. La inoculación directa al suelo de <em>A. brasilense</em> Cd mostró un efecto significativo en la reducción de la concentración de CLas en los árboles de Lm en condiciones de invernadero.

AbstractCandidatus Liberibacter solanacearum (CLso) is an economically important plant-pathogen of tomato (Solanum lycopersicum) crops in the United States, Mexico, Central America, and New Zealand. Currently, there are no reports of resistance to CLso in tomato cultivars. Identification and development of CLso-resistant cultivars may offer the most efficient way to manage this tomato disease. Resistance of 46 tomato landraces collected in different regions of Mexico, representing a wide range of genetic variability from this country was evaluated. Two assays were done in consecutively years to assess the resistance to CLso under greenhouse conditions. Plants from both tests were inoculated with CLso through 20 Bactericera cockerelli insects per plant. In the first trial, landraces FC22 and FC44 showed a significantly higher proportion of resistant plants, less symptoms severity, and longer incubation time, followed by landraces FC40 and FC33 compared with the rest of the 42 landraces and 2 susceptible cultivars 60 days post inoculation (dpi). In the second assay, only landraces FC22 and FC44 had again significantly higher proportion of resistant plants, less symptoms severity, relative lower CLso titers, and longer incubation time in comparison with landraces FC40 and FC33 and the two susceptible cultivars 60 dpi, corroborating their resistance to CLso. Presence of CLso DNA in all resistant plants from both assays discards scape plants and indicates that the methodology used was adequate to discriminate between resistant and susceptible plants. These results confirm that landraces FC22 and FC44 are promising resistant sources for the development of CLso-resistant cultivars of tomato.Author summaryThe bacterium “Candidatus Liberibacter solanacearum” (CLso) is an important plant-pathogen of tomato crops in the United States, Mexico, Central America, and New Zealand. Tomato growers are lacking of cultivars with resistance to this pathogen and the development of resistant cultivars of this crop would make a sustainable business for these growers and healthy tomato consumption for humans. Tomato landraces from countries that are center of domestication of cultivated crops like Mexico, are potentially sources of resistance to plant-pathogens. Therefore, two tests were done looking for resistance sources to this pathogen and we found two tomato landraces (FC22 and FC44) showing high level of resistance to CLso because they had significantly higher resistant plants, less symptoms severity, lower CLso DNA concentration, and delay of the first symptoms in the inoculated plants in comparison with the two commercial cultivars and 44 tomato landraces collected from Mexico 60 days post infection. These landraces are promising resistant sources for the development of CLso-resistant cultivars of tomato.

AbstractCandidatusAccumulibacter phosphatis (CAP) and its sub-clades-level diversity has been associated and implicated in successful phosphorus removal performance in enhanced biological phosphorus removal (EBPR). Development of high-throughput untargeted methods to characterize clades of CAP in EBPR communities can enable a better understanding of Accumulibacter ecology at a higher-resolution beyond OTU-level in wastewater resource recovery facilities (WRRFs). In this study, for the first time, using integrated 16S rRNA gene sequencing, oligotyping and genome-resolved metagenomics, we were able to reveal clade-level differences in Accumulibacter communities and associate the differences with two different full-scale EBPR configurations. The results led to the identification and characterization of a distinct and dominant Accumulibacter oligotype - Oligotype 2 (belonging to Clade IIC) and its matching MAG (RC14) associated with side-stream EBPR configuration. We are also able to extract MAGs belonging to CAP clades IIB (RCAB4-2) and II (RC18) which did not have representative genomes before. This study demonstrates and validates the use of a high-throughput approach of oligotyping analysis of 16S rRNA gene sequences to elucidate CAP clade-level diversity. We also show the existence of a previously uncharacterized diversity of CAP clades in full-scale EBPR communities through extraction of MAGs, for the first time from full-scale facilities.