Stevia rebaudiana belongs to the Asteraceae family with high economic and medicinal potential. Th... more Stevia rebaudiana belongs to the Asteraceae family with high economic and medicinal potential. This article describes and illustrates morphological and histological aspects of leaves and reproductive organs, and the germination process, to provide detailed information on this species and to contribute to taxonomic, phylogenetic and pharmacobotanical projects. The fruit is a cypsela, small, simple, dry, indehiscent, monospermic, light or dark colored, with aristate pappus, and the seed presents a spatulate axile embryo. Germination is phaneroepigeal with a pivotal root system and many absorbing root hairs. The leaves are simple, elliptical to obovate, with two types of trichomes (glandular and tector), with a short petiole, exhibiting an opposite decussate phyllotaxy. Our results showed 37.5% germination after 12 days, only in the dark cypsela, the light colored being considered unviable. The inflorescence is paniculate and the florets are grouped in capitula with isomorphic ends, mo...
Pollen morphology characterization is important in taxonomy, conservation and plant breeding, and... more Pollen morphology characterization is important in taxonomy, conservation and plant breeding, and pollen viability studies can support breeding programs. This study investigated pollen morphology and male fertility in 18 species of Bromeliaceae with ornamental potential. For morphological characterization, pollen grains were acetolyzed and characterization of exine was done using scanning and transmission electron microscopy. Pollen viability was investigated by in vitro germination and histochemical tests. Species belonging to Aechmea and Ananas genera presented medium size pollen, except for Ae. fasciata, with large pollen. Al. nahoumii, P. sagenarius and the Vriesea species analyzed showed large pollen, except for V. carinata, with very large pollen. Pollen of Aechmea, Ananas and P. sagenarius presented bilateral symmetry, diporate, exine varying from tectate to semitectate. Al. nahoumii and Vriesea species presented pollen with bilateral symmetry, monocolpate; exine was semitect...
Anais da Academia Brasileira de Ciencias, Jan 16, 2017
The genus Passiflora is the most diversified of the Passifloraceae, and its palynology presents w... more The genus Passiflora is the most diversified of the Passifloraceae, and its palynology presents wide morphological variability. The objective of the study was to evaluate the pollen morphology of 18 Passiflora species in order to identify informative pollinic characteristics to contribute to the taxonomic classification of the genus. The morphology of the pollen grains and the exine structure were investigated using light microscopy and scanning electron microscopy. Differences in the pollen morphology were found in the studied species, mainly in terms of shape, pollen aperture and ornamentation pattern of the exine. Most of the species belonging to the subgenus Passiflora presented ornamented 6-syncolpate pollen grains with an oblate-spheroidal shape and an exine with large lumens. In the subgenus Decaloba the pollen grains were 6-colporate, 12-colpate and 12-colporate, with subprolate to prolate-spheroidal shape, as well as an exine with smaller lumen size and few ornamented. The ...
There is a very effective cross-talk between signals triggered by reactive oxygen species and hor... more There is a very effective cross-talk between signals triggered by reactive oxygen species and hormonal responses in plants, activating proteins/enzymes likely to be involved in stress tolerance. Abscisic acid (ABA) is known as a stress hormone that takes part in the integration of signals. This work aimed to characterize the biochemical response and ultrastructural changes induced by cadmium (Cd) in the Micro-Tom (MT) sitiens ABA-deficient mutant (sit) and its wild-type (MT) counterpart. MT and sit plants were grown over a 96-h period in the presence of Cd (0, 10, and 100 μM CdCl2). The overall results indicated increases in lipid peroxidation, hydrogen peroxide content and in the activities of the key antioxidant enzymes such as catalase, glutathione reductase, and ascorbate peroxidase in both genotypes. On the other hand, no alteration was observed in chlorophyll content, while the activity of another antioxidant enzyme, superoxide dismutase, remained constant or even decreased in...
Biochemical responses inherent to antioxidant systems as well morphological and anatomical proper... more Biochemical responses inherent to antioxidant systems as well morphological and anatomical properties of photomorphogenic, hormonal and developmental tomato mutants were investigated. Compared to the non-mutant Micro-Tom (MT), we observed that the malondialdehyde (MDA) content was enhanced in the diageotropica (dgt) and lutescent (l) mutants, whilst the highest levels of hydrogen peroxide (H2O2) were observed in high pigment 1 (hp1) and aurea (au) mutants. The analyses of antioxidant enzymes revealed that all mutants exhibited reduced catalase (CAT) activity when compared to MT. Guaiacol peroxidase (GPOX) was enhanced in both sitiens (sit) and notabilis (not) mutants, whereas in not mutant there was an increase in ascorbate peroxidase (APX). Based on PAGE analysis, the activities of glutathione reductase (GR) isoforms III, IV, V and VI were increased in l leaves, while the activity of superoxide dismutase (SOD) isoform III was reduced in leaves of sit, epi, Never ripe (Nr) and green...
Witches’ broom disease of cacao is caused by the pathogenic fungus Moniliophthora perniciosa. By ... more Witches’ broom disease of cacao is caused by the pathogenic fungus Moniliophthora perniciosa. By using tomato (Solanum lycopersicum) cultivar Micro-Tom (MT) as a model system, we investigated the physiological and metabolic consequences of M. perniciosa infection to determine whether symptoms result from sink establishment during infection. Infection of MT by M. perniciosa caused reductions in root biomass and fruit yield, a decrease in leaf gas exchange, and down-regulation of photosynthesis-related genes. The total leaf area and water potential decreased, while ABA levels, water conductance/conductivity, and ABA-related gene expression increased. Genes related to sugar metabolism and those involved in secondary cell wall deposition were up-regulated upon infection, and the concentrations of sugars, fumarate, and amino acids increased. 14C-glucose was mobilized towards infected MT stems, but not in inoculated stems of the MT line overexpressing CYTOKININ OXIDASE-2 (35S::AtCKX2), su...
Moniliophthora perniciosa causes witches' broom disease of cacao and inflicts symptoms sugges... more Moniliophthora perniciosa causes witches' broom disease of cacao and inflicts symptoms suggestive of hormonal imbalance. We investigated whether infection of the tomato (Solanum lycopersicum) model system Micro-Tom (MT) by the Solanaceae (S)-biotype of M. perniciosa, which causes stem swelling and hypertrophic growth of axillary shoots, results from changes in host cytokinin metabolism. Inoculation of an MT-transgenic line that overexpresses the Arabidopsis CYTOKININ OXIDASE-2 gene (35S::AtCKX2) resulted in a reduction in disease incidence and stem diameter. RNA-seq analyses of infected MT and 35S::AtCKX2 revealed the activation of cytokinin-responsive marker genes when symptoms were conspicuous. The expression of an M. perniciosa tRNA-ISOPENTENYL-TRANSFERASE suggests the production of isopentenyladenine (iP), detected in mycelia grown in vitro. Inoculated MT stems showed higher levels of dihydrozeatin and trans-zeatin but not iP. The application of benzyladenine induced symptoms similar to infection, whereas applying the cytokinin receptor inhibitors LGR-991 and PI55 decreased symptoms. Moniliophthora perniciosa produces iP that might contribute to cytokinin synthesis by the host, which results in vascular and cortex enlargement, axillary shoot outgrowth, reduction in root biomass and an increase in fruit locule number. This strategy may be associated with the manipulation of sink establishment to favour infection by the fungus.
The annatto (Bixa orellana) is the only species of the Bixaceae family. From the seeds an importa... more The annatto (Bixa orellana) is the only species of the Bixaceae family. From the seeds an important food colorant is obtained, bixin, for the industry and domestic use. More recently studies have focused more extensively in medicinal purpose of the species. Due to structural and physiologic characteristics, the seeds have low germination rate, around 30 %. The irradiation of seeds with gamma radiation can promote the increase and/or acceleration of germination, better plant developmentand productivity, among other aspects. The radiation doses used for this purpose should not cause genetic modifications in the organism, hence experimentation is needed to define the appropriate doses. Absence of research done annatto related to the use of the irradiation aiming at the increase of germination rates lead to the structural characterization of the annatto seeds submitted to gamma radiation through transmission (TEM) and scanning electron microscopy (SEM). The objective of this study was t...
Piracicaba, 13418-9000, SP, Brazil ** Histopathology and Plant Structural Biology Laboratory, Cen... more Piracicaba, 13418-9000, SP, Brazil ** Histopathology and Plant Structural Biology Laboratory, Center of Nuclear Energy in Agriculture, Universidade de São Paulo, Piracicaba, 13418-9000, SP, Brazil *** Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1301, USA **** Institute for Technology and Research/Processes Engineering Postgraduate Program, Universidade Tiradentes, Aracaju, 49032-490, SE, Brazil ✉Corresponding author: G. R. Salazar-Banda, gianrsb@gmail.com
Aluminum (Al) is one of the relevant abiotic stress factors in acidic soils, mainly in tropical a... more Aluminum (Al) is one of the relevant abiotic stress factors in acidic soils, mainly in tropical areas which consequently reduces crop productivity. Forage grasses of genus Brachiaria present stress tolerance, however there are intra- and interspecific differences to Al-toxicity among Brachiaria species. Differential tolerance of plant genotypes is the most promising approach to understand mechanisms that confer Al-tolerance in plants. The primary site of Al-toxicity is the apical meristem and the first visible symptom is the inhibition of root elongation. In consequence plants reduce nutrients uptake and growth. This study explores the effects of Al-toxicity in two Brachiaria genotypes (Brachiaria brizantha cv. Marandu and Brachiaria brizantha cv. Xaraés), mainly focusing in epidermal damage and root dry mass. Seedlings were germinated for 8 days on vermiculite. Uniform seedlings were placed in plastic pots (5 plants per pots) with 2.0 L of Furlani & Furlani solution (20% ionic stre...
Folhas, frutos e sementes de melão (Cucumis melo) Amarelo foram inoculados com Acidovorax avenae ... more Folhas, frutos e sementes de melão (Cucumis melo) Amarelo foram inoculados com Acidovorax avenae subsp. citrulli (Aac1) com o objetivo de estudar a colonização e penetração desse patógeno, utilizando microscopia eletrônica de varredura. Nas folhas coletadas 24, 48, 72, 96 e 120 h após a inoculação foram observadas células bacterianas agregadas e interligadas por fibrilas e muito raramente isoladas. Células bacterianas foram localizadas predominantemente nos flanges cuticulares da epiderme abaxial, na base dos tricomas tectores, próximas aos estômatos diacíticos e no interior dos poros estomáticos. Nos frutos com 37 dias de idade, 24 h após a inoculação, bactérias foram observadas na superfície e concentradas ao redor de estômatos e lenticelas, e nas amostras com 48 h, na polpa do fruto. Nas demais amostras (72 e 96 h) foram encontradas poucas ou até mesmo nenhuma bactéria na superfície dos frutos. Nos frutos com 51 dias de idade foi constatada uma expressiva colonização da superfíci...
Stevia rebaudiana belongs to the Asteraceae family with high economic and medicinal potential. Th... more Stevia rebaudiana belongs to the Asteraceae family with high economic and medicinal potential. This article describes and illustrates morphological and histological aspects of leaves and reproductive organs, and the germination process, to provide detailed information on this species and to contribute to taxonomic, phylogenetic and pharmacobotanical projects. The fruit is a cypsela, small, simple, dry, indehiscent, monospermic, light or dark colored, with aristate pappus, and the seed presents a spatulate axile embryo. Germination is phaneroepigeal with a pivotal root system and many absorbing root hairs. The leaves are simple, elliptical to obovate, with two types of trichomes (glandular and tector), with a short petiole, exhibiting an opposite decussate phyllotaxy. Our results showed 37.5% germination after 12 days, only in the dark cypsela, the light colored being considered unviable. The inflorescence is paniculate and the florets are grouped in capitula with isomorphic ends, mo...
Pollen morphology characterization is important in taxonomy, conservation and plant breeding, and... more Pollen morphology characterization is important in taxonomy, conservation and plant breeding, and pollen viability studies can support breeding programs. This study investigated pollen morphology and male fertility in 18 species of Bromeliaceae with ornamental potential. For morphological characterization, pollen grains were acetolyzed and characterization of exine was done using scanning and transmission electron microscopy. Pollen viability was investigated by in vitro germination and histochemical tests. Species belonging to Aechmea and Ananas genera presented medium size pollen, except for Ae. fasciata, with large pollen. Al. nahoumii, P. sagenarius and the Vriesea species analyzed showed large pollen, except for V. carinata, with very large pollen. Pollen of Aechmea, Ananas and P. sagenarius presented bilateral symmetry, diporate, exine varying from tectate to semitectate. Al. nahoumii and Vriesea species presented pollen with bilateral symmetry, monocolpate; exine was semitect...
Anais da Academia Brasileira de Ciencias, Jan 16, 2017
The genus Passiflora is the most diversified of the Passifloraceae, and its palynology presents w... more The genus Passiflora is the most diversified of the Passifloraceae, and its palynology presents wide morphological variability. The objective of the study was to evaluate the pollen morphology of 18 Passiflora species in order to identify informative pollinic characteristics to contribute to the taxonomic classification of the genus. The morphology of the pollen grains and the exine structure were investigated using light microscopy and scanning electron microscopy. Differences in the pollen morphology were found in the studied species, mainly in terms of shape, pollen aperture and ornamentation pattern of the exine. Most of the species belonging to the subgenus Passiflora presented ornamented 6-syncolpate pollen grains with an oblate-spheroidal shape and an exine with large lumens. In the subgenus Decaloba the pollen grains were 6-colporate, 12-colpate and 12-colporate, with subprolate to prolate-spheroidal shape, as well as an exine with smaller lumen size and few ornamented. The ...
There is a very effective cross-talk between signals triggered by reactive oxygen species and hor... more There is a very effective cross-talk between signals triggered by reactive oxygen species and hormonal responses in plants, activating proteins/enzymes likely to be involved in stress tolerance. Abscisic acid (ABA) is known as a stress hormone that takes part in the integration of signals. This work aimed to characterize the biochemical response and ultrastructural changes induced by cadmium (Cd) in the Micro-Tom (MT) sitiens ABA-deficient mutant (sit) and its wild-type (MT) counterpart. MT and sit plants were grown over a 96-h period in the presence of Cd (0, 10, and 100 μM CdCl2). The overall results indicated increases in lipid peroxidation, hydrogen peroxide content and in the activities of the key antioxidant enzymes such as catalase, glutathione reductase, and ascorbate peroxidase in both genotypes. On the other hand, no alteration was observed in chlorophyll content, while the activity of another antioxidant enzyme, superoxide dismutase, remained constant or even decreased in...
Biochemical responses inherent to antioxidant systems as well morphological and anatomical proper... more Biochemical responses inherent to antioxidant systems as well morphological and anatomical properties of photomorphogenic, hormonal and developmental tomato mutants were investigated. Compared to the non-mutant Micro-Tom (MT), we observed that the malondialdehyde (MDA) content was enhanced in the diageotropica (dgt) and lutescent (l) mutants, whilst the highest levels of hydrogen peroxide (H2O2) were observed in high pigment 1 (hp1) and aurea (au) mutants. The analyses of antioxidant enzymes revealed that all mutants exhibited reduced catalase (CAT) activity when compared to MT. Guaiacol peroxidase (GPOX) was enhanced in both sitiens (sit) and notabilis (not) mutants, whereas in not mutant there was an increase in ascorbate peroxidase (APX). Based on PAGE analysis, the activities of glutathione reductase (GR) isoforms III, IV, V and VI were increased in l leaves, while the activity of superoxide dismutase (SOD) isoform III was reduced in leaves of sit, epi, Never ripe (Nr) and green...
Witches’ broom disease of cacao is caused by the pathogenic fungus Moniliophthora perniciosa. By ... more Witches’ broom disease of cacao is caused by the pathogenic fungus Moniliophthora perniciosa. By using tomato (Solanum lycopersicum) cultivar Micro-Tom (MT) as a model system, we investigated the physiological and metabolic consequences of M. perniciosa infection to determine whether symptoms result from sink establishment during infection. Infection of MT by M. perniciosa caused reductions in root biomass and fruit yield, a decrease in leaf gas exchange, and down-regulation of photosynthesis-related genes. The total leaf area and water potential decreased, while ABA levels, water conductance/conductivity, and ABA-related gene expression increased. Genes related to sugar metabolism and those involved in secondary cell wall deposition were up-regulated upon infection, and the concentrations of sugars, fumarate, and amino acids increased. 14C-glucose was mobilized towards infected MT stems, but not in inoculated stems of the MT line overexpressing CYTOKININ OXIDASE-2 (35S::AtCKX2), su...
Moniliophthora perniciosa causes witches' broom disease of cacao and inflicts symptoms sugges... more Moniliophthora perniciosa causes witches' broom disease of cacao and inflicts symptoms suggestive of hormonal imbalance. We investigated whether infection of the tomato (Solanum lycopersicum) model system Micro-Tom (MT) by the Solanaceae (S)-biotype of M. perniciosa, which causes stem swelling and hypertrophic growth of axillary shoots, results from changes in host cytokinin metabolism. Inoculation of an MT-transgenic line that overexpresses the Arabidopsis CYTOKININ OXIDASE-2 gene (35S::AtCKX2) resulted in a reduction in disease incidence and stem diameter. RNA-seq analyses of infected MT and 35S::AtCKX2 revealed the activation of cytokinin-responsive marker genes when symptoms were conspicuous. The expression of an M. perniciosa tRNA-ISOPENTENYL-TRANSFERASE suggests the production of isopentenyladenine (iP), detected in mycelia grown in vitro. Inoculated MT stems showed higher levels of dihydrozeatin and trans-zeatin but not iP. The application of benzyladenine induced symptoms similar to infection, whereas applying the cytokinin receptor inhibitors LGR-991 and PI55 decreased symptoms. Moniliophthora perniciosa produces iP that might contribute to cytokinin synthesis by the host, which results in vascular and cortex enlargement, axillary shoot outgrowth, reduction in root biomass and an increase in fruit locule number. This strategy may be associated with the manipulation of sink establishment to favour infection by the fungus.
The annatto (Bixa orellana) is the only species of the Bixaceae family. From the seeds an importa... more The annatto (Bixa orellana) is the only species of the Bixaceae family. From the seeds an important food colorant is obtained, bixin, for the industry and domestic use. More recently studies have focused more extensively in medicinal purpose of the species. Due to structural and physiologic characteristics, the seeds have low germination rate, around 30 %. The irradiation of seeds with gamma radiation can promote the increase and/or acceleration of germination, better plant developmentand productivity, among other aspects. The radiation doses used for this purpose should not cause genetic modifications in the organism, hence experimentation is needed to define the appropriate doses. Absence of research done annatto related to the use of the irradiation aiming at the increase of germination rates lead to the structural characterization of the annatto seeds submitted to gamma radiation through transmission (TEM) and scanning electron microscopy (SEM). The objective of this study was t...
Piracicaba, 13418-9000, SP, Brazil ** Histopathology and Plant Structural Biology Laboratory, Cen... more Piracicaba, 13418-9000, SP, Brazil ** Histopathology and Plant Structural Biology Laboratory, Center of Nuclear Energy in Agriculture, Universidade de São Paulo, Piracicaba, 13418-9000, SP, Brazil *** Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1301, USA **** Institute for Technology and Research/Processes Engineering Postgraduate Program, Universidade Tiradentes, Aracaju, 49032-490, SE, Brazil ✉Corresponding author: G. R. Salazar-Banda, gianrsb@gmail.com
Aluminum (Al) is one of the relevant abiotic stress factors in acidic soils, mainly in tropical a... more Aluminum (Al) is one of the relevant abiotic stress factors in acidic soils, mainly in tropical areas which consequently reduces crop productivity. Forage grasses of genus Brachiaria present stress tolerance, however there are intra- and interspecific differences to Al-toxicity among Brachiaria species. Differential tolerance of plant genotypes is the most promising approach to understand mechanisms that confer Al-tolerance in plants. The primary site of Al-toxicity is the apical meristem and the first visible symptom is the inhibition of root elongation. In consequence plants reduce nutrients uptake and growth. This study explores the effects of Al-toxicity in two Brachiaria genotypes (Brachiaria brizantha cv. Marandu and Brachiaria brizantha cv. Xaraés), mainly focusing in epidermal damage and root dry mass. Seedlings were germinated for 8 days on vermiculite. Uniform seedlings were placed in plastic pots (5 plants per pots) with 2.0 L of Furlani & Furlani solution (20% ionic stre...
Folhas, frutos e sementes de melão (Cucumis melo) Amarelo foram inoculados com Acidovorax avenae ... more Folhas, frutos e sementes de melão (Cucumis melo) Amarelo foram inoculados com Acidovorax avenae subsp. citrulli (Aac1) com o objetivo de estudar a colonização e penetração desse patógeno, utilizando microscopia eletrônica de varredura. Nas folhas coletadas 24, 48, 72, 96 e 120 h após a inoculação foram observadas células bacterianas agregadas e interligadas por fibrilas e muito raramente isoladas. Células bacterianas foram localizadas predominantemente nos flanges cuticulares da epiderme abaxial, na base dos tricomas tectores, próximas aos estômatos diacíticos e no interior dos poros estomáticos. Nos frutos com 37 dias de idade, 24 h após a inoculação, bactérias foram observadas na superfície e concentradas ao redor de estômatos e lenticelas, e nas amostras com 48 h, na polpa do fruto. Nas demais amostras (72 e 96 h) foram encontradas poucas ou até mesmo nenhuma bactéria na superfície dos frutos. Nos frutos com 51 dias de idade foi constatada uma expressiva colonização da superfíci...
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