We sprayed defence-related plant growth regulators (salicylic acid, methyl jasmonate and ethephon) on one-month-old Habanero pepper seedlings cultivated in vitro. Twenty-four hours later, we inoculated the seedlings with a virulent strain of Phytophthora capsici and periodically evaluated the disease symptoms. At the concentrations used, neither salicylic acid nor methyl jasmonate generated a protective effect in the seedlings, which died less than 10 days post inoculation. However, the treatment with 5 mM ethephon delayed or prevented disease symptoms in 30% of the seedlings. Interestingly, blocking the ethylene receptor with a previous application of 300 μM silver nitrate impeded the protective effects of ethephon. This result demonstrated that the plant resistance response required the perception of ethylene. Analysis of transcript populations in ethephon-treated seedlings revealed a direct correlation between survival and the accumulation of PR1, a gene marker of the systemic acquired resistance (SAR). Although the ethephon treatment also modified transcript levels of the plant defensin PDF1.2, a marker of the induced systemic resistance (ISR), in this case the accumulation also occurred when the ethylene receptor was blocked, suggesting a non-specific effect. The ethephon treatment did not modify the expression of NPR1 (a key transcriptional regulator of plant defence). Interestingly, transgenic pepper seedlings overexpressing endogenous PR10 or esterase genes, which are induced by the ET treatment, completely resisted the infection, which corroborated the importance of these genes in the defence response. Our results suggest that ethylene induced a systemic defence response in susceptible seedlings, possibly in an NPR1-independent pathway.

This study's aim was to establish a protocol for the micropropagation of G. skinneri using temporary immersion system (TIS). Different concentrations of 6-Benzylaminopurine (0, 1, 2, and 3 mg L −1 ), three different systems of cultivate semi-solid (SS) and liquid media under partial (PI) and temporary immersion systems (TIS), different compositions of the inorganic salts, and the number of subcultures were evaluated. The results showed a maximum of 16.56 shoots per explant obtained through TIS, adjusting all the parameters evaluated in our study. One higher number of shoots per explant was observed in the micropropagation of G. skinneri TIS compared to SS and PI. While the use of 3 mg L −1 of BAP + MS (Murashige and Skoog) media was better than 3 mg L −1 of BAP VW (Vacint and Went) for the generation of a greater number of shoots per explant, 6.33 and 2.72, respectively. The immersion frequency of 2 min every 4 h allowed the production to be scaled to 8.54 shoots per explant. While it was necessary to perform three subcultures every 30 days, to obtain 16.56 shoots per explant, a rooting phase was not required due to the generation of adventitious roots during the different subcultures. However, a phase of elongation of the regenerated plants with ½ MS + GA3 (gibberellic acid) was needed to guarantee 100% survival in the process of acclimatization. In conclusion, this plant production system can be applied for the commercial micropropagation of this species for ornamental purposes, as well as for its reintroduction in protected natural areas.

El chile Manzano o Cera (Capsicum pubescens), es una planta perenne originaria de las tierras altas de América del Sur. Durante su almacenamiento, el principal problema que presenta es su testa, lo cual ocasiona una disminución de la germinación en condiciones naturales. Debido a que existe poca información sobre la germinación, es necesario implementar alternativas que garanticen el recurso dentro de un programa de mejoramiento genético. El objetivo fue evaluar el efecto de ácido sulfúrico (H2SO4), peróxido de hidrógeno (H2O2) y ácido giberélico-3 (C19H22O6) sobre el porcentaje de emergencia y características de plántulas de semillas de C. pubescens. El experimento se realizó en la Unidad de Manejo y Conservación de Recursos Genéticos de la Facultad de Ciencias Biológicas y Agropecuarias de la Universidad Veracruzana. Se utilizaron semillas de C. pubescens provenientes de la localidad de Huatusco, Veracruz, México, almacenadas a temperatura ambiente durante un año. Los tratamientos estudiados fueron: inmersión en H2SO4 (100, 75, 60 %; 30 min); inmersión en H2O2 (20, 10, 15 %; 15 min), inmersión en C19H22O6 (25, 20, 15 mg; 24 h) y el tratamiento testigo. Los resultados en el presente estudio revelan diferencias estadísticas significativas (P ≤ 0,01) para todas las variables evaluadas. El mejor porcentaje de germinación se provocó con inmersión en C19H22O6 (15 mg; 24 h) y H2O2 (20 %; 15 min). El tratamiento con H2SO4 fue perjudicial ya que no hubo emergencia.

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Taro is important for its nutritional content, medicinal use, and bioethanol production. The aim of the present study was to compare different semi-automated bioreactors (SABs) during in vitro multiplication of C. esculenta. The SABs used were temporary immersion bioreactors (TIBs), SETIS™ bioreactors and ebb-and-flow bioreactors; semi-solid culture medium was used as a control treatment. At 30 d of culture, different developmental variables, determination of chlorophyll, stomatal content, and survival percentage during acclimatization were evaluated. SABs increased the shoot multiplication rate relative to the semi-solid medium; however, the SETIS™ bioreactor showed the highest shoot production, with 36 shoots per explant, and the highest chlorophyll content. The stomatal index was higher in the semi-solid medium compared to the SABs, while the percentage of closed stomata was higher in the SABs than in the semi-solid culture medium. The survival rate during acclimatization showed no differences among the culture systems assessed, obtaining survival rates higher than 99%. In conclusion, the SETIS™ bioreactor showed the highest multiplication rate; however, other bioreactor alternatives are available for semi-automation and cost reduction for micropropagation of C. esculenta.

Malanga (Colocasia esculenta) is a plant genetic resource that requires biotechnological strategies for conservation and propagation. One time-, labor-, and space-saving option is in vitro conservation and regeneration. The objective of this study was to develop a protocol for in vitro regeneration and conservation of germplasm of C. esculenta var. criolla. For conservation through minimal growth, we assessed several concentrations of Murashige and Skoog (MS) medium (one-third, one-half, and three-quarter strength), the growth retardant ancymidol (0, 1, 2, and 3 mg·L−1), and the osmoregulator polyethylene glycol (PEG-8000 mw) at different concentrations (0, 10, 20, and 30 g·L−1). For in vitro conservation, the percent survival, shoot number and length, and number of leaves and roots per explant were evaluated after 24 weeks. For in vitro regeneration, different concentrations of thidiazuron (TDZ: 0, 0.5, 1, 1.5, and 2 mg·L−1) and 6-benzylaminopurine (BAP; 0, 1, 2, 3, and 4 mg·L−1) were evaluated. After 4 weeks of cultivation, the percent response, shoot number, and number of leaves per explant were recorded. During in vitro conservation, it was noted that the treatment including 2 mg·L−1 ancymidol resulted in a retarded development, without affecting the survival of the C. esculenta germplasm. With regard to shoot regeneration, 7.60 shoots per explant were obtained using 2 mg·L−1 TDZ. Finally, 98% survival was achieved during the acclimatization process. This study will contribute to the establishment of genetic improvement programs through in vitro conservation and propagation of this valuable plant genetic resource.

<em>Bacillus subtilis</em> presenta actividad antagónica contra fitopatógenos. En el presente estudio, se identificaron los hongos asociados al ahogamiento en plántulas de calabacita y se evaluó la efectividad de la cepa QST 713 de <em>B. subtilis</em> ante la infección combinada de los hongos aislados. Los patógenos se aislaron de plántulas de calabacita con síntomas de ahogamiento. Se inocularon plántulas de calabacita var. Grey zucchini con propágulos de tres patógenos a una concentración de 4×105 UFC de cada patógeno. Se evaluó la efectividad de <em>B. subtilis</em> (2, 4 y 6×107 UFC mL-1) y se comparó con metil tiofanato + propamocarb clorhidrato (preventiva y curativa). La incidencia se evaluó a los tres, seis, nueve y 12 días (ddi). Se aislaron e identificaron tres hongos de 100 aislamientos: <em>Phytophthora capsici</em> (62%), <em>Rhizoctonia solani</em> (26%) y <em>Fusarium oxysporum</em> (12%). Se observó la eficiencia de <em>B. subtilis</em>, con una reducción en la incidencia de la enfermedad conforme se incrementó la concentración. Doce días después de la inoculación, la incidencia del ahogamiento en los tratamientos con <em>B. subtilis</em> varió de 18.3 a 41%. El tratamiento de <em>B. subtilis</em> (6×107 UFC mL-1) fue estadísticamente igual a metil tiofanato + propamocarb clorhidrato (curativo). La cepa QST 713 de<em> B. subtilis</em> controló un 81.7% el ahogamiento de plántulas de calabacita, aplicada de manera preventiva a una concentración de 6×107 UFC mL-1.

The APETALA2/Ethylene response factor (AP2/ERF) family of transcription factors (TFs) plays crucial roles in the regulation of gene expression during plant development and in response to biotic and abiotic stress. Although AP2/ERFs have been implicated in a range of plant stress responses, this review focuses on ERFs in the context of the plant response to other organisms, primarily not only pathogenic but also symbiotic. The ERF subfamily is particularly important in the establishment and the tight regulation of plant defences through a balance of positive and negative transcriptional regulation. The expression of the ERFs is induced by pathogens with different lifestyles and they have been implicated in resistance to biotrophs, necrotrophs and hemibiotrophs, but members also play important roles in other plant-microbe interactions, for example, nodule formation in legumes. ERFs achieve this, in part, by acting as integrators in the crosstalk between signalling pathways mediated by ethylene (ET), jasmonic acid, salicylic acid and other plant hormones to modulate gene expression according to the stimuli sensed. This review collates recent findings on the regulation of this family of TFs, including transcriptional and post-translational regulation. Although DNA binding is typically conferred through the characteristic AP2 domain, the function of other domains including the EDLL and ERF-associated amphiphilic repression (EAR) domains in regulating gene expression is discussed. Finally, the potential for ERFs to be used to enhance resistance to pathogens in crops is considered.