A pesquisa relacionada com a resposta inata das plantas á estresses tem atraído muito interesse por a similitude com as respostas reportadas nos mamíferos. Assim, foi proposta uma aproximação ás respostas de defesa aos estresses abióticos através da avaliação no modelo biológico Lycopersicon spp. da atividade enzimática caspase 10 em resposta da indução com CuCl2 y paraquat. Os ensaios da atividade caspase 10 mostraram um máximo de atividade na concentração 40 mM, 9 horas depois da elicitação, com uma pendente de 0,0054 e 0,0022 para L. hirsutum y L. esculentum respectivamente. A atividade comparativa dos genótipos sugere que, embora os dois genótipos presenteassem atividade, a resposta é menos variável de maior magnitude para L. hirsutum. A elicitação com paraquat presenteou a maior atividade caspase 10 em torno das 2 horas depois do estímulo, com uma pendente de 0,013 e 0,0012 para L. hirsutum y L. esculentum respectivamente. A determinação direita da atividade caspase 10 nas plântulas de tomate tratadas com cobre e paraquat, usando um substrato específico para mamíferos, mostrou que estes mecanismos estão relacionados provavelmente com processos de apoptose depois da indução abiótica.

Plant defense responses to stress have attracted interest because of their similarity to reported mammalian stress responses. To investigate plant responses to abiotic stress, caspase 10-like enzymatic activities of Lycopersicon hirsutum and Lycopersicon esculentum were assayed in response to copper chloride and paraquat induction. Caspase 10-like activity was greatest at 40 mM CuCl2 at 9 h after elicitation in both L. hirsutum and L. esculentum, for which respective response slopes (Δ absorbance per Δ minute) were 0.0054 and 0.0022 . The response for L. hirsutum was less variable and significantly greater than for L. esculentum. Elicitation of caspase 10-like activity by paraquat was greatest at around 2 h after treatment in both species with slopes of 0.013 and 0.0012, respectively for L. hirsutum and L. esculentum. The direct determination of caspase 10-like activity in tomato seedlings treated with copper and paraquat, using a specific substrate for mammals, suggested that the observed responses were related to apoptosis processes under abiotic induction.

As plantas estão expostas a agentes externos bióticos e abióticos que podem produzir dano nas celulas. Os agentes bióticos incluem moléculas produzidas por patógenos e os agentes abióticos incluem radiação ultravioleta, metais pesados e os agentes xenobióticos como os herbicidas. Devido à importancia do estresse abiotico e o limitado conhecimiento sob as respostas de defensa das plantas ao estresse, este estudo foi feito usando a citometría de fluxo para avaliar os eventos endocelulares de duas espécies de tomate: Lycopersicon hirsutum e Lycopersicon esculentum depois da exposição a 10 mM CuCl2 e 1% do paraquat. Durante os primeiros 30 min da exposição ao CuCl2 os valores da intensidade média da fluorescência em ambas as espécies diminuiu mais do 50% quando comparado com os controles não tratados. No caso do tratamento com o paraquat, depois dos primeiros 30 minutos a produção das espécies reativas do oxigênio, (avaliada pela presença do ânion superóxido) na espécie L. hirsutum e L. esculentum foi de 32,9% e 25,4%, respectivamente. A hiperpolarização das mitocôndrias das duas espécies do tomate foi observada durante as 2 primeiras horas. A ausência de dano no início ao nível da membrana e os efeitos adversos na mitocôndria causados pelos tratamentos sugerem que poda haver mecanismos adicionais que levam à morte celular, e que estes mecanismos podem estar associados à apoptose.

Plants are often exposed to external biotic or abiotic agents that can damage cells. Biotic agents include molecules produced by pathogens, and abiotic agents include ultraviolet radiation, heavy metals and xenobiotic agents such as herbicides. Because of the importance of abiotic stresses and the limited knowledge of the defense responses of plants to stresses, a study was conducted using flow cytometry to evaluate endocellular events in protoplasts of two tomato species, Lycopersicon hirsutum and Lycopersicon esculentum, following exposure to 10 mM CuCl2 and 1% paraquat. During the first 30 min of exposure to 10 mM CuCl2, mean fluorescence intensity values in both species decreased by more than 50% compared to the untreated control. During the first 30 min of paraquat treatment, the production of reactive oxygen species, evaluated as the incidence of protoplasts in which the superoxide anion was present, was 32.9 % and 25.4%, respectively, for L. hirsutum and L. esculentum. Hyperpolarization of the mitochondria for both tomatoes species was observed during the first 2 h. The absence of early membrane damage and the markedly detrimental effects of the treatments on the mitochondria suggest that additional mechanisms which lead to cell death may be involved in these processes, and that these mechanisms may be associated with apoptosis.

The Lulo or naranjilla (Solanum quitoense Lam.) and the tree tomato or tamarillo (Solanum betaceum Cav. Sendt.) are both Andean tropical fruit species with high nutritional value and the potential for becoming premium products in local and export markets. Herein, we present a report on the genetic characterization of 62 accessions of lulos (n = 32) and tree tomatoes (n = 30) through the use of PCR-based markers developed from single-copy conserved orthologous genes (COSII) in other Solanaceae (Asterid) species. We successfully PCR amplified a set of these markers for lulos (34 out of 46 initially tested) and tree tomatoes (26 out of 41) for molecular studies. Six polymorphic COSII markers were found in lulo with a total of 47 alleles and five polymorphic markers in tree tomato with a total of 39 alleles in the two populations. Further genetic analyses indicated a high population structure (with F ST > 0.90), which may be a result of low migration between populations, adaptation to various niches and the number of markers evaluated. We propose COSII markers as sound tools for molecular studies, conservation and the breeding of these two fruit species.

Se estudió la latencia y germinación de semillas de guanábana y chirimoya con el fin de categorizar la latencia de las simientes y desarrollar un protocolo de rompimiento de ésta; conocimiento básico para el establecimiento y monitoreo de un duplicado de seguridad en las colecciones de campo, por la vía de almacenamiento a largo plazo de las unidades de propagación sexuales. No se detectó latencia exógena, a través de la imbibición obtenida por las semillas. Se encontró, a través de pruebas de viabilidad, con tetrazolio, que en cada uno de los taxa existe alrededor de un 20% de unidades no viables en el conjunto de semillas aparentemente normales. La estratificación caliente húmeda, por espacio de 90 días, produjo rompimiento de la latencia, al igual que la imbibición con AG3, con obtención del mejor resultado al imbibir la simiente en 800 ppm de la hormona. En chirimoya se obtuvo efectos sinérgicos al combinar el tratamiento de 800 ppm de AG3 y estratificación caliente húmeda durante 90 días, lo cual no fue evidente en el caso de la guanábana. A partir de los resultados se clasificó el bloqueo de la germinación de las semillas de las dos especies, como latencia morfofisiológica simple, no profunda. La caracterización definida, junto con el protocolo de remoción, apoyan el establecimiento de un duplicado de seguridad de la colección de campo, por la vía de semilla, con un concepto dinámico que se esboza en este escrito.

Cherimoya (Annona cherimola) and soursop (Annona muricata) seed germination and dormancy were studied in order to characterize a dormancy type for both taxa, develop dormancy breaking procedures, and obtain a basic knowledge required for seed viability monitoring for the establishment of long-term seed conservation duplicate of field germplasm collection and utilization of stored germplasm. The presence of exogenic dormancy in seeds was not detected during the imbibition of seeds. About 20% of the apparently normal seeds in both species were non viable based on the results of tetrazolium test. Seed dormancy release was obtained after warm stratification under humid conditions, as well as seed imbibition with GA3, demonstrating the best results for 90 days stratification and 800 ppm of the hormone. In cherimoya, the combination of warm stratification with 800 ppm GA3 produced the highest seed germination, which did not happen with the soursup seeds. Based on the results, the seed dormancy for both species was classified as simple, non-deep morphophysiological dormancy. A dynamic concept described in the current paper for seed behaviour in terms of dormancy and germination provides a support to establish a security duplicate of seed field collection for both species.