O Brasil destaca-se como um dos maiores produtores mundiais de mamão, fruto apreciado em todo o mundo pelo sabor e polpa delicada. Os compostos voláteis contribuem para a formação do aroma do fruto, o que faz deles essenciais para o desenvolvimento de características sensoriais que definem sua apreciação pelos consumidores. Os principais compostos de aroma do mamão incluem, principalmente, terpenos, ésteres, aldeídos, álcoois, ácidos orgânicos e cetonas, com destaque para o monoterpeno linalool que é o composto mais abundante na cultivar \'Golden\'. Embora a biossíntese de compostos voláteis seja particularmente afetada pelos tratamentos para consevação pós-colheita, estes são essenciais para a comercialização do mamão, em vista de sua alta perecibilidade. O uso de baixas temperaturas tem sido um dos métodos mais empregados para extensão de vida pós-colheita do mamão. Precedentes da literatura indicam que o tratamento pós-colheita com metil jasmonato (MJ) é capaz de reduzir possíveis efeitos prejudiciais decorrentes do armazenamento a baixa temperatura. Além disso, a aplicação do metil jasmonato em frutos é capaz de estimular a atividade de enzimas das vias de produção de compostos voláteis. Desta forma, o presente trabalho tem por objetivo avaliar os efeitos da aplicação pós-colheita do MJ em mamão (Carica papaya L. cv \'Golden\'), focando os efeitos sobre as vias de biossíntese de componentes voláteis do aroma, em frutos amadurecidos a temperatura de 22ºC, assim como em outros armazenados a 10ºC seguido de transferência a 22ºC para o pleno amadurecimento. Além dos perfis de compostos voláteis, também foram avaliados os perfis de respiração, produção de etileno, cor da casca, quantificação de MJ e expressão gênica de linalool sintase (LIS). Dada a importância do linalool para o aroma característico do mamão, as variações na transcrição de um gene da linalool sintase foram avaliadas buscando correlacioná-las aos efeitos dos tratamentos na produção dos compostos voláteis. O tratamento com MJ influenciou a produção de compostos voláteis, particularmente de linalool e hexanal nos grupos mantidos a 10ºC. Os frutos tratados com o hormônio apresentaram maior abundância do composto quando comparados ao grupo controle. Embora o protocolo de tratamento empregado não tenha conseguido recuperar os altos níveis encontrados nos frutos armazenados a 22ºC, não se exclui a possibilidade de que outros desenhos experimentais possam responder de maneira ainda mais satisfatória a este mesmo tratamento / Brazil stands out as one of the world\'s largest producers of papaya, fruit appreciated worldwide for it taste and delicate pulp. The volatile compounds contribute to the formation of the flavor of the fruit, making them essential for the development of sensory characteristics that define their appreciation by consumers. The main papaya flavor compounds include mainly terpenes, esters, aldehydes, alcohols, organic acids and ketones, especially the monoterpene linalool which is the most abundant compound in the cultivar \'Golden\'. Although the biosynthesis of volatile compounds is particularly affected by postharvest treatments for conservation, those are essential for the marketing of papaya, in view of their high perishability. The use of low temperatures has been one of the most used methods for extension of papaya postharvest life. Previous literature indicate that postharvest treatment with methyl jasmonate (MJ) is capable of reducing possible adverse effects arising from storage at low temperature. Furthermore, the application of methyl jasmonate in fruits is able to stimulate the activity of the enzymes of volatiles production pathways. Thus, this study aims to evaluate the effects of postharvest application of MJ in papaya (Carica papaya L. cv \'Golden\'), focusing on the effects in the biosynthetic pathways of volatile aroma compounds in fruit ripened to temperature of 22ºC, as well as other stored at 10ºC followed by transfer to 22ºC for the complete maturation. In addition to the volatile compounds profiles were also evaluated respiration profiles, ethylene production, peel color, quantification of MJ and gene expression of linalool synthase (LIS). Given the importance of linalool to the characteristic aroma papaya, changes in the transcription of a linalool synthase gene were evaluated seeking to correlate them to the treatment effects on the production of volatile compounds. Treatment with MJ influence the production of volatile compounds, particularly linalool and hexanal in the groups kept at 10ºC. Fruits treated with the hormone had higher abundance of the compound when compared to the control group. Although the treatment protocol employee has not been able to recover the high levels found in fruits stored at 22ºC, do not exclude the possibility that other experimental designs can respond even more satisfactorily to this same treatment.

Moléculas de origem vegetal foram há muito testadas como fonte de drogas antineoplásicas com sucesso promissor. Este trabalho trata dos efeitos antiangiogênicos do Metil Jasmonato. Este derivado hidrofóbico do ácido jasmônico foi demonstrado anteriormente como um agente de dano seletivo para a mitocôndria de células neoplásicas. In vitro, o Metil Jasmonato 1-10 mM promoveu a morte celular de células endoteliais humanas de cordão umbilical (HUVEC) e de melanoma murino (B16 -F10), enquanto concentrações micromolares foram inócuas. A inclusão do Metil Jasmonato em liposomos de fosfatidilcolina e em um nanocarreador hidrofílico baseado em açúcar mostrou efeitos diferenciais sobre a citotoxicidade. A interrupção do ciclo celular foi observada em concentrações citotóxicas, enquanto a diminuição na produção de VEGF e algum grau de autofagia foram sugeridos em concentrações micromolares. In vivo, Metil Jasmonato 1-10mM foi francamente tóxico, e reduziu a densidade de vasos em membranas corioalantóicas de embrião de galinha (CAM). Entretanto, concentrações entre 1-10 ?M produziram um efeito complexo. Ocorreu aumento no brotamento capilar, mas os novos vasos apresentaram-se frágeis e menos organizados que os controles correspondentes. Sugere-se que, além da toxicidade direta, a ação do Metil Jasmonato sobre a angiogênese seja relevante para seu efeito antineoplásico. / Molecular plant components have long been tested as sources for antineoplasic drugs with promising success. The present work deals with the anti-angiogenic effects of Methyl Jasmonate. This hydrophobic Jasmonate derivative was previously demonstrated to selectively damage the mitochondria of cancer cells. In vitro, 1-10 mM Methyl Jasmonate induced the cell death of the human umbilical vein endothelial cells (HUVEC) and the Murine melanoma cells (B16-F10), while micromolar concentrations were ineffective. Methyl Jasmonate inclusion in phosphatidylcholine liposomes and in an hydrophilic sugar based nanocarrier presented differential effects upon citotoxicity. Cell cycle arrest was observed in citotoxic concentrations, while VEGF withdrawn and some autophagy was suggested in the micromolar range. In vivo, 1-10mM concentrations were explicitly toxic and reduced the vessel density of the Chorioallantoic Membrane of the Chicken Embryo (CAM). However, 1-10 ?M concentrations produced a complex effect. There was increased capillary budding, but the new vessels were leakier and less organized than corresponding controls. It is suggested that not only direct toxicity, but also the drug effects upon angiogenesis are relevant to the antineoplasic effects of Methyl Jasmonate.

O Brasil destaca-se como um dos maiores produtores mundiais de mamão, fruto apreciado em todo o mundo pelo sabor e polpa delicada. Os compostos voláteis contribuem para a formação do aroma do fruto, o que faz deles essenciais para o desenvolvimento de características sensoriais que definem sua apreciação pelos consumidores. Os principais compostos de aroma do mamão incluem, principalmente, terpenos, ésteres, aldeídos, álcoois, ácidos orgânicos e cetonas, com destaque para o monoterpeno linalool que é o composto mais abundante na cultivar \'Golden\'. Embora a biossíntese de compostos voláteis seja particularmente afetada pelos tratamentos para consevação pós-colheita, estes são essenciais para a comercialização do mamão, em vista de sua alta perecibilidade. O uso de baixas temperaturas tem sido um dos métodos mais empregados para extensão de vida pós-colheita do mamão. Precedentes da literatura indicam que o tratamento pós-colheita com metil jasmonato (MJ) é capaz de reduzir possíveis efeitos prejudiciais decorrentes do armazenamento a baixa temperatura. Além disso, a aplicação do metil jasmonato em frutos é capaz de estimular a atividade de enzimas das vias de produção de compostos voláteis. Desta forma, o presente trabalho tem por objetivo avaliar os efeitos da aplicação pós-colheita do MJ em mamão (Carica papaya L. cv \'Golden\'), focando os efeitos sobre as vias de biossíntese de componentes voláteis do aroma, em frutos amadurecidos a temperatura de 22ºC, assim como em outros armazenados a 10ºC seguido de transferência a 22ºC para o pleno amadurecimento. Além dos perfis de compostos voláteis, também foram avaliados os perfis de respiração, produção de etileno, cor da casca, quantificação de MJ e expressão gênica de linalool sintase (LIS). Dada a importância do linalool para o aroma característico do mamão, as variações na transcrição de um gene da linalool sintase foram avaliadas buscando correlacioná-las aos efeitos dos tratamentos na produção dos compostos voláteis. O tratamento com MJ influenciou a produção de compostos voláteis, particularmente de linalool e hexanal nos grupos mantidos a 10ºC. Os frutos tratados com o hormônio apresentaram maior abundância do composto quando comparados ao grupo controle. Embora o protocolo de tratamento empregado não tenha conseguido recuperar os altos níveis encontrados nos frutos armazenados a 22ºC, não se exclui a possibilidade de que outros desenhos experimentais possam responder de maneira ainda mais satisfatória a este mesmo tratamento / Brazil stands out as one of the world\'s largest producers of papaya, fruit appreciated worldwide for it taste and delicate pulp. The volatile compounds contribute to the formation of the flavor of the fruit, making them essential for the development of sensory characteristics that define their appreciation by consumers. The main papaya flavor compounds include mainly terpenes, esters, aldehydes, alcohols, organic acids and ketones, especially the monoterpene linalool which is the most abundant compound in the cultivar \'Golden\'. Although the biosynthesis of volatile compounds is particularly affected by postharvest treatments for conservation, those are essential for the marketing of papaya, in view of their high perishability. The use of low temperatures has been one of the most used methods for extension of papaya postharvest life. Previous literature indicate that postharvest treatment with methyl jasmonate (MJ) is capable of reducing possible adverse effects arising from storage at low temperature. Furthermore, the application of methyl jasmonate in fruits is able to stimulate the activity of the enzymes of volatiles production pathways. Thus, this study aims to evaluate the effects of postharvest application of MJ in papaya (Carica papaya L. cv \'Golden\'), focusing on the effects in the biosynthetic pathways of volatile aroma compounds in fruit ripened to temperature of 22ºC, as well as other stored at 10ºC followed by transfer to 22ºC for the complete maturation. In addition to the volatile compounds profiles were also evaluated respiration profiles, ethylene production, peel color, quantification of MJ and gene expression of linalool synthase (LIS). Given the importance of linalool to the characteristic aroma papaya, changes in the transcription of a linalool synthase gene were evaluated seeking to correlate them to the treatment effects on the production of volatile compounds. Treatment with MJ influence the production of volatile compounds, particularly linalool and hexanal in the groups kept at 10ºC. Fruits treated with the hormone had higher abundance of the compound when compared to the control group. Although the treatment protocol employee has not been able to recover the high levels found in fruits stored at 22ºC, do not exclude the possibility that other experimental designs can respond even more satisfactorily to this same treatment.

Photosynthesis is the most important process for nearly all life on earth. Photosynthetic organisms capture and transfer light energy from the sun into chemical energy which in turn provides a resource base for heterotrophic organisms. Natural light regimes are irregular and vary over magnitudes. At a certain light intensity, metabolic processes cannot keep up with the electron flow produced by the primary photoreactions, and thus reactive oxygen species (ROS) are produced. ROS are highly reactive and can damage the photosynthesis apparatus and hence plants have evolved several photoprotection mechanisms to avoid the formation of ROS. The aim of this thesis was to examine the ecological effects of variations in photoprotection in plants. In particular I wanted to study the effect on fitness and the interaction with herbivorous insects of plants with different ability in photoprotection. To study this I used wild-type and transgenic Arabidopsis thaliana plants and grew them under natural conditions in field experiments in our botanical garden in Umeå, northern Sweden. For the investigation of the plant-insect interaction, a specialist on Brassicaceae (Plutella xylostella – diamondback moth) and a generalist herbivore (Spodoptera littoralis - Egyptian cotton worm) were used. Plants that are genetically deficient in one of the photoprotection mechanisms showed reduced fitness under natural conditions. I could thus show that feedback de-excitation (FDE) is the most important photoprotection mechanism, because a lack of FDE showed the highest reduction in fitness. The comparison of field grown wild-type with FDE mutant plants, using molecular biology methods, revealed large changes in gene transcription and metabolic composition. In particular, the jasmonate pathway was upregulated in light stressed plants, especially in plants lacking FDE. Jasmonate in turn is known to be a chemical compound which induces herbivore resistance genes and other stress responses. Specialist and generalist insect herbivores responded differently in feeding (dual-choice and no-choice) and oviposition experiments with field grown plants that differed in FDE. Female diamondback moths were attracted by induced defense compounds whereas the larvae avoided these plants in feeding experiments. Generalist larvae preferred, and showed a higher survival rate, on less light-stressed plants compared to more light-stressed plants. Combining molecular biology with ecological experiments is a challenging task. To summarize my experiences, I have produced a guide for experiments on transgenic plants in common gardens. In future investigations it is important to examine natural variations in photoprotection to elucidate selection pressures on specific genes.

Moléculas de origem vegetal foram há muito testadas como fonte de drogas antineoplásicas com sucesso promissor. Este trabalho trata dos efeitos antiangiogênicos do Metil Jasmonato. Este derivado hidrofóbico do ácido jasmônico foi demonstrado anteriormente como um agente de dano seletivo para a mitocôndria de células neoplásicas. In vitro, o Metil Jasmonato 1-10 mM promoveu a morte celular de células endoteliais humanas de cordão umbilical (HUVEC) e de melanoma murino (B16 -F10), enquanto concentrações micromolares foram inócuas. A inclusão do Metil Jasmonato em liposomos de fosfatidilcolina e em um nanocarreador hidrofílico baseado em açúcar mostrou efeitos diferenciais sobre a citotoxicidade. A interrupção do ciclo celular foi observada em concentrações citotóxicas, enquanto a diminuição na produção de VEGF e algum grau de autofagia foram sugeridos em concentrações micromolares. In vivo, Metil Jasmonato 1-10mM foi francamente tóxico, e reduziu a densidade de vasos em membranas corioalantóicas de embrião de galinha (CAM). Entretanto, concentrações entre 1-10 ?M produziram um efeito complexo. Ocorreu aumento no brotamento capilar, mas os novos vasos apresentaram-se frágeis e menos organizados que os controles correspondentes. Sugere-se que, além da toxicidade direta, a ação do Metil Jasmonato sobre a angiogênese seja relevante para seu efeito antineoplásico. / Molecular plant components have long been tested as sources for antineoplasic drugs with promising success. The present work deals with the anti-angiogenic effects of Methyl Jasmonate. This hydrophobic Jasmonate derivative was previously demonstrated to selectively damage the mitochondria of cancer cells. In vitro, 1-10 mM Methyl Jasmonate induced the cell death of the human umbilical vein endothelial cells (HUVEC) and the Murine melanoma cells (B16-F10), while micromolar concentrations were ineffective. Methyl Jasmonate inclusion in phosphatidylcholine liposomes and in an hydrophilic sugar based nanocarrier presented differential effects upon citotoxicity. Cell cycle arrest was observed in citotoxic concentrations, while VEGF withdrawn and some autophagy was suggested in the micromolar range. In vivo, 1-10mM concentrations were explicitly toxic and reduced the vessel density of the Chorioallantoic Membrane of the Chicken Embryo (CAM). However, 1-10 ?M concentrations produced a complex effect. There was increased capillary budding, but the new vessels were leakier and less organized than corresponding controls. It is suggested that not only direct toxicity, but also the drug effects upon angiogenesis are relevant to the antineoplasic effects of Methyl Jasmonate.

Thesis (M.Sc.(Agricultural Management )) -- University of Limpopo, 2020 / Avocado fruit ‘Hass’ harvested during early-season and exposed to temperature at 5.5°C for 28 d are susceptible to chilling injury (CI); and therefore, develop poor skin colour during ripening. In ‘Hass’ avocado fruit, skin colour change during ripening is used by European market to indicate fruit ripeness and softness. Therefore, the aim of this study was to evaluate the use of hot water (HW) and methyl jasmonate (MJ) as postharvest treatment dips to mitigate CI; and thereby, enhance ‘Hass’ avocado fruit peel colour during ripening. Fruit were harvested randomly from 5 selected trees treated alike during early season (April 2018); and thereafter, transported to the laboratory. At the laboratory, experiments of this study were divided into 2: experiment (1) fruit were dipped into HW (38, 42 and 46°C for 30, 25 and 20 min, respectively); and experiment (2) fruit were dipped into MJ (10 and 100 µmol/L for 2 min) treatments. In both experiments after these treatments, fruit were allowed to dry for 60 minutes at ambient (±25°C) temperature and untreated fruit were used as control. Thereafter, fruit were stored at commercial shipping temperature (5.5°C) for up to 28 d. After removal from cold storage, fruit were ripened at ambient temperature (±25°C) and evaluated every after 2 d for weight loss, firmness loss, objective colour parameters (lightness-L*, chroma-C* and hue angle-h*), subjective colour (eye colour) and ripening percentage. However, chilling injury (CI) and electrolyte leakage (EL) were evaluated immediately after removal from cold storage. The results showed that HW significantly (P< 0.05) increased weight and firmness loss during ripening. Furthermore, HW reduced EL and external chilling injury (ECI) of ‘Hass’ avocado fruit during cold storage. In addition, the results showed that HW had significant effect (P< 0.05) on colour parameter L* and eye colour rating, but did not affect (P> 0.05) C* and h*. Avocado ‘Hass’ fruit subjected to HW at 42°C/25 and 46°C/20 min developed purple colour (eye colour rating 4.47 and 4.36, respectively) during ripening when compared with HW at 38°C/30 min and control fruit. Moreover, results showed that dipping fruit in 10 µmol/L had a significant effect (P< 0.05) on reducing weight loss during ripening. Methyl jasmonate (10 and 100 µmol/L) treatment reduced EL and alleviated external chilling injury (ECI) of ‘Hass’ fruit during cold storage. The results showed that MJ (10 and 100 µmol/L) treatments had significant effect (P< 0.05) on colour parameter L*, h* and eye colour rating, but did not affect (P> 0.05) C*. Furthermore, ‘Hass’ fruit treated with 10 and 100 µmol/L MJ reached the purple skin colour (eye rating 5.39 and 5.19, respectively) during ripening. Fruit dipped in MJ (10 µmol/L) had low weight loss when compared with fruit treated with MJ (100 µmol/L). In conclusion, the results of this study indicated that HW (42°C/25 minutes) and MJ (10 µmol/L) effectively alleviated external chilling injury; and therefore, improved ‘Hass’ skin colour development during ripening / Agricultural Research Council-Institute (Agriseta) and University of Limpopo

Maize is an important food crop in most parts of the world including the United States. The plants growing in the field are constantly challenged with various biotic stresses like insect herbivores and fungal pathogens. The physical wounds produced on the growing crops by the insects render the plants more vulnerable to the fungal pathogens. Hence developing both insect and fungal resistant maize varieties is crucial to benefit more from the harvest. Several studies have been in advance in this direction and as a consequence insect, in particular lepidopteran larve resistant maize genotype Mp708 and Aspergillus flavus resistant genotype Mp313E were developed. This study particularly focuses on understanding the functional involvement of the major phytohormones in the signal transduction and expression of the unique defense protein, Maize insect resistance 1-cysteine protease (Mir1-CP) shown to accumulate in response to herbivory by lepidopteran larvae, Spodoptera frugiperda (Fall armyworm, FAW) as a defense mechanism. Using a pharmacological approach involving exogenous hormone and hormone inhibitor treatments and analyzing the expression and accumulation of Mir1-CP protein and mir1 transcript by immunoblot and qRT-PCR analysis respectively, both JA and ET were found to be involved in mediating Mir1-CP accumulation with JA acting upstream of ET. Results also indicate that Mir1-CP accumulation involves both transcriptional and post-transcriptional (or post-translational) regulations. A different part of the study involved in understanding and evaluating the performance of Aspergillus flavus on the resistant and susceptible maize genotypes during infection. As of part of this study I also analyzed and compared the defense response offered by the resistant maize genotype, Mp313E and the susceptible genotype, Va35 by looking at the expression levels of the various defense related genes. The potency of the resistant maize genotype in sustaining the fungal infection in the field was of particular focus. Resistant maize genotype Mp313E was found to potentially oppose A.flavus proliferation and colonization and also delay aflatoxin biosynthesis unlike Va35. The up regulation of the maize defense genes during the early time points of infection, in Mp313E, indicate the potential role of these genes in conferring resistance against fungal pathogens.

No description available.

A interacao planta-patogeno desencadeia uma serie de sinais que ainda nao estao completamente elucidados. Uma das respostas e a reacao de hipersensibilidade (RH), onde ocorre a morte celular programada no sitio da infeccao, impedindo a proliferacao do patogeno. Acredita que a morte celular e provocada pelo aumento do ERO, principalmente peroxido de hidrogenio (H2O2) e com o acumulo de acido salicilico (AS) que inibe a catalase, enzima responsavel pela transformacao de H2O2 em H2O e O2. Alem disso, ocorre o aumento da sintese e liberacao dos compostos fenolicos e alteracao da parede celular dos vegetais, com o aumento das atividades de diversas enzimas, capazes de degradar a parede celular da planta e do microrganismo invasor, liberando fragmentos que podem atuar como moleculas sinalizadoras, tornando as plantas mais resistentes. Nesse trabalho as celulas de Rubus fruticosus (amora-preta) foram tratadas, separadamente, com tres diferentes moleculas elicitoras, ou seja, moleculas capazes de ativar o mecanismo de defesa das plantas, o acido salicilico (AS), o metil jasmonato (MeJA) e ramnoglucuronogalactana (F-I), na concentracao de 1 Êmol/L durante 1h, para o estudo dos componentes extracelulares liberados e das modificacoes dos monossacarideos da parede celular durante resposta de hipersensibilidade. A concentracao de proteinas totais extracelulares foi aumentada com os indutores F-I e MeJA. A atividade enzimatica de -D-xilosidase nao se alterou na presenca de F-I, AS e MeJA. Entretanto, o MeJA tem a capacidade de aumentar as atividades das enzimas -D-galactosidase, -Dglucosidase, quitinase e laminarinase e inibir as atividades das enzimas galacturonase e -Lfucosidase na concentracao e tempo usado. O AS e F-I provocaram um aumento nas atividades de galacturonase e quitinase e inibiram a laminarinase. A aplicacao exogena de F-I e AS induziram a liberacao de compostos fenolicos para meio extracelular, que provavelmente, foi decorrente da tentativa das celulas de se protegerem de microrganismos invasores, com um decrescimo desses compostos no meio intracelular. O MeJA nao foi capaz de alterar a sintese de compostos fenolicos totais intracelulares e extracelulares e de acucares extracelulares, em tais condicoes. Tambem F-I e AS nao alteraram o teor de acucar redutor extracelular. O MeJA foi mais efetivo na producao de ERO durante 30 minutos de incubacao na concentracao de1 Êmol/L . F-I foi tambem ativador na liberacao de ERO, no entanto, o AS provocou inibicao. Os principais monossacarideos neutros que constitui a parede celular de suspensao de celulas de Rubus fruticosus sao as glucose (55-61%), arabinose (22-29%) e manose (13,8-15%). Ocorrendo em menor concentracoes os monossacarideos de fucose (0,65-1,2%), galactose (0,5-0,8%), xilose (0,5-0,8%) e ramnose (aproximadamente 0,5%).Os monossacarideos ramnose, fucose, xilose e galactose de parede celular tiveram um decrescimo na presenca do AS e um aumento na presenca de MeJA. Entretanto, o AS e o MeJA nao alteraram o percentual de arabinose, manose e glucose. O F-I foi capaz de aumentar o percentual dos monossacarideos ramnose e fucose e diminuir de glucose. Os resultados obtidos demonstram que a via de ativacao dos mecanismos de defesa da celula vegetal, induzida pelo MeJA, difere das vias ativadas pelo AS e F-I, pois o F-I e o AS induziram a liberacao de compostos fenolicos e o MeJA provocou aumento nas atividades enzimaticas, principalmente que atuam na parede celular da propria planta. O AS e o F-I foram mais efetivos no aumento das atividades enzimaticsa relacionadas a defesa da planta, as quais agem nas paredes de diversos fitopatogenos, sendo que as enzimas que podem atuar na parede celular da propria planta foram inibidas ou nao sofreram alteracao. / The plant-pathogen interactions trigger a series of signals that are not yet completely understood. One of the mechanisms is the hypersensitive response (HR), which is characterized by cell death in the infection site in order to prevent pathogen proliferation. Our previous studies with different elicitors demonstrated the correlation between the formation of reactive oxygen species (ROS) and cell wall degradation. Here, the cells were elicited with 1 mol/L salicylic acid (SA), methyl jasmonate (MeJA) or acid polysaccharide (rhamnoglucuronogalactan, F-I) (1mol/L) from characterization the extracellular components released and the modifications of the monosaccharide composition in cell wall during a hypersensitive response in Rubus fruticosus (blackberry-black).The extracellular proteins released to the extracellular were increased with the inducers molecules F-I and MeJA. The -D-xylosidase enzymatic activities didnt change in the presence of F-I, SA and MeJA. The time-course curves for -D-galactosidase, -D-glucosidase activities in fraction E were most effective for MeJA, while F-I and AS inhibited -Dgalactosidase. Also, the MeJA has ability to activate laminarinase and chitinase enzymatic activities and inhibit galacturonase and -L-fucosidase enzymatic activities. After 1h, the SA and F-I caused an increase galacturonase and chitinase activities and inhibited laminarinase enzymatic activity. Also, the time-course curves chitinase in the fraction increased with SA.The F-I and SA increased extracellular phenolic compounds, although they decreased them in the fraction I. MeJA was unable to change the synthesis of either intracellular or extracellular phenolic compounds. The data suggest that F-I and AS modulate the defense responses of plants through a via different that of MeJA. The extracellular reducing sugar didnt change with F-I, SA and MeJA.The MeJA was more effective in the release ROS incubation of 30 minutes at concentration of 1 mol/L. However, the presence of SA caused inhibition and F-I activated of ROS by cells.The main constituents of neutral sugars in the cell wall of Rubus fruticosus were glucose (55-61%), arabinose (22-29%) and mannose (13.8-15%). Minor constituents were fucose (0.65-1.2%), galactose (0.5- 0.8%), xylose (0.5-0.8%) and rhamnose (~0.5%). SA decreased the rhamnose and fucose concentrations; F-I both decreased the percentage of mannose and glucose and increased rhamnose and fucose. MeJA, in turn, increased the percentage of rhamnose, xylose and galactose. The data suggest that F-I and SA modulate the defense responses of plants through a mechanism unrelated to the MeJA via. Since the F-I and the SA induced the release phenolic compounds and the MeJA increased in enzymatic activities, mainly age in the own plant cell wall. The SA and F-I were more effective in the increasing defense enzyme-related activity of the plant that acts on the walls of several phytopathogens, and the enzymes that can act in the cell wall of the plant were inhibited or did not change.

Waxflower (Chamelaucium spp. and hybrids) is the singlemost important Australian export cut-flower. The major problem in waxflower trading is flower abscission after harvest. While several factors are involved, ethylene production resulting from preharvest infection with the fungus Botrytis cinerea is the most important cause. The general objectives of this study were to investigate the biology of Botrytis infecting waxflower flowers and potential elicitation of host defence against this pathogen. Effects of anti-ethylene and S-carvone treatments on Botrytis-induced flower abscission were also evaluated. Infection of flowers by Botrytis was studied on two waxflower cvs. Mullering Brook and My Sweet Sixteen using light and electron microscopy. Conidial germination and protoappressorial formation occurred within 8 h post-inoculation (hpi). Infection of most floral organs, including petals, anthers and filaments, stigma, and hypanthium, was within 24 hpi. Infection cushions on stamen bases were formed at 36 hpi by saprophytic hyphae that originated from anthers. This infection route probably gives rise to the typical tan-coloured Botrytis symptoms that appear to radiate from this part of the flower. Subcuticular hyphae were present at very high density near stamen bases. They evidently resulted at multiple penetrations from single infection cushions. Flower abscission occurred at 72 hpi. At this time, floral tube tissues remained uninfected. This temporal pattern infers the possible transmission of a signal (e.g. ethylene) upon Botrytis infection (6–36 hpi) that intiates a defence response of shedding infected flowers (72 hpi). Susceptibility of waxflower before and after harvest to B. cinerea under various environmental conditions (laboratory, greenhouse, and field) was investigated. Flowers, either on plants or on cut stems showed similar susceptibility to B. cinerea and abscised under cool temperatures (~20 ºC) and high humidity (>95% RH) conditions following infection. Compared to cv. Mullering Brook, cv. My Sweet Sixteen was somewhat more resistant to B. cinerea infection under field conditions. Constitutive and inducible antifungal compounds in waxflower flower tissues were screened in cvs. CWA Pink, Stephan’s Delight, Mullering Brook and My Sweet Sixteen using thin layer chromatography bioassays with isolates of B. cinerea and Alternaria alternata (pathogenic) and Cladosporium cladosporioides (non-pathogenic). Common inhibition zone observed at Rf 0.28–0.38, 0.46–0.56 and 0.67–0.76 contained phenolic compounds. There were at least five (cv. Mullering Brook) and one (cv. My Sweet Sixteen) inducible antifungal phenolic compounds as judged by increases in inhibition area as a result of B. cinerea infection and methyl jasmonate treatment. The total areas of B. cinerea- and MeJA-induced inhibition zones were approximately 2.0- and 2.5-folds greater, respectively, than zones from control flowers. Preharvest sprays of three different known host plant defence elicitors, methyl jasmonate (MeJA), benzothiadiazole (BTH), and silicon (Si), were applied to waxflower cvs. Mullering Brook and My Sweet Sixteen plants. BTH or Si sprays generally had no significant effect on postharvest Botrytis severity on either cultivar. MeJA sprays did not reduce B. cinerea on cv. Mullering Brook. MeJA slightly suppressed B. cinerea on cv. My Sweet Sixteen at 500 and 750 µM. Overall, field applications of these host plant defence elicitor chemicals as spray treatments had little effect on vase life, water uptake and relative fresh weight of the cut sprigs. Moreover, they did not appreciably suppress B. cinerea or associated postharvest floral abscission. The efficacy of combined elicitor treatments and combined pre- and postharvest MeJA treatments were assessed. Preharvest foliar applications of MeJA (1000 µM; 2 or 4 times), MeJA (1000 µM) combined with BTH (150 mg/L), and MeJA combined with Si (1500 mg SiO2/L) generally did not suppress postharvest B. cinerea development and flower abscission from harvested sprigs. A pre- plus post-harvest 1000 µM MeJA spray treatment consistently but only slightly suppressed B. cinerea infection on flowers from both pot- and field-grown plants. Pre- and post-harvest MeJA treatments reduced B. cinerea development, but increased flower abscission. Combined MeJA and anti-ethylene treatments were then screened for potential to suppress B. cinerea while preventing flower abscission. However, the combined MeJA and 1-MCP treatment reduced neither Botrytis disease nor flower abscission on sprigs from pot- and field-grown plants. The combined MeJA and STS treatment reduced disease severity for up to 6 days on sprigs harvested from pot-grown plants but tended to increase Botrytis severity on sprigs from field-grown plants 6 days after inoculation. Antifungal effects of the essential oil S-carvone against B. cinerea germination and mycelial growth were demonstrated in vitro. Inhibition increased with increasing S-carvone concentrations from 0.64 mM to 5.08 mM. However, in planta, S-carvone concentrations in this range did not affect either Botrytis disease levels or flower abscission on cut waxflower flowers.