Search

Cadmium (Cd) is one of the most threatening soil and water contaminants in agricultural settings. In previous studies, we observed that Cd affects the metabolism and physiology of tomato (Solanum lycopersicum) plants even after short-term exposure. The objective of this research was to use cross-genotype grafting to distinguish between root- and shoot-mediated responses of tomato genotypes with contrasting Cd tolerance at the early stages of Cd exposure. This study provides the first report of organ-specific contributions in two tomato genotypes with contrasting Cd tolerance: Solanum lycopersicum cv. Calabash Rouge and Solanum lycopersicum cv. Pusa Ruby (which have been classified and further characterized as sensitive (S) and tolerant (T) to Cd, respectively). Scion S was grafted onto rootstock S (S/S) and rootstock T (S/T), and scion T was grafted onto rootstock T (T/T) and rootstock S (T/S). A 35 μM cadmium chloride (CdCl

A first insight into the effects of cadmium exposure on the phosphoproteome of tomato plants by performing a comparative analysis of tomato genotypes with contrasting cadmium tolerance.

The present study aimed to investigate the Cd-induced transgenerational effects on plants. Grafted tomato plants, which exhibited the same cultivar as scion and distinct cultivars with contrasting Cd-tolerance as rootstocks, were grown in soil without and with artificial addition of Cd (less than 2.0, and 6.9 mg kg-1 of Cd, respectively) in a pot experiment carried out in a greenhouse. Their fruits were harvested to extract seeds (i.e., the progenies), which were sown over either Cd-free (control) or Cd-containing germitest paper (germination testing paper with 0 and 35 μM of CdCl2, respectively) and grown in a growth chamber. The immediate progeny of all grafting combinations from stressed plants presented an elevated germinability, despite high internal Cd concentration. When sown in Cd-containing germitest paper, the immediate progeny of plants grown in soil with no Cd addition was generally able to maintain or even increase the content of carotenoids and chlorophylls a and b (up to 93.3, 62.8 and 76.1%, respectively), indicating a Cd-induced hormetic effect on photosynthetic pigments. Two of the grafting combinations from stressed plants yielded seeds that generated seedlings with enhanced dry mass when they were sown in Cd-free media (~41%), suggesting a Cd-induced transgenerational enhancement of biomass production. Because only one tomato cultivar was used as scion, data indicated that type and degree of Cd-induced transgenerational effects depend strongly on signals generated and/or processed in roots of the parental plants. When sown in Cd-contaminated germitest paper, the immediate progeny of Cd-treated plants presented major reductions in the leaf area (35-69%) and content of photosynthetic pigments (57-93%) in comparison to the progeny from control plants. However, one of the grafting combinations exhibited satisfactory performance after "double" exposure to Cd, showing 91% of the biomass that was produced in the seedlings of control seeds from control plants. Further investigation indicated that adjustments in the chlorophyll fluorescence behavior might counterbalance losses in leaf pigments and area. Taken together, our data provide new insights on the origin, outcomes and mode of action of the Cd-induced transgenerational effects.

Peach palm (Bactris gasipaes Kunth) has been micropropagated from pre-procambial cells that provide stem-like cell niches, (i.e., pre-procambial cells), multipotent, pluripotent and totipotent for direct vascularization, adventitious buds and somatic embryogenesis, respectively. The direct induction of adventitious buds and somatic embryogenesis reduces the frequency of mutations when compared to indirect morphogenesis. Long-term in vitro cultivation of perennial species such as peach palm cause the clones to age and deteriorate; however, the consequences for morphogenesis potential are not fully clear. The morphogenic potential of peach palm clones established and in vitro cultivated for 8 years (regeneration of adventitious buds without callus formation) was investigated in leaves, roots and stem bases using histological and histochemical analyses. Data from long-term cultures (8-years-old) was compared to data from short-term cultures (1-year-old). Morphogenic pathways monitoring for direct induction of somatic embryos and adventitious buds revealed a strong morphogenic reduction potential in the pre-procambial cells, parenchyma cells in the proximal region of stem bases, and external cells of leaf sheaths. Initial cells of shoot apical meristems and pre-procambial cells commit cell reprogramming to the undifferentiated state and subsequent acquisition of cellular competence. These results are applicable in the micropropagation of peach palm, with consideration to obtaining clones and their long-term in vitro culture.

This work aimed to develop a reliable and fast approach to estimate the plant tolerance degree to heavy metal (HM) phytotoxicity. Two independent experiments were carried out using tomato accessions, with contrasting morphological features, that were grown in a hydroponic solution containing different CdCl2 concentrations for 7 days. Plant dry weight and chlorophyll content (SPAD units) were evaluated, and tolerance degree to Cd toxicity was estimated according to the tolerance index (TI), which is a new mathematical formula based on plant biomass proposed in this study. Although with different magnitudes, tomato exhibited reductions in their dry weight concurrently with the increasing CdCl2 concentration. By contrast, chlorophyll content presented no standard response, decreasing and even increasing according to CdCl2 concentrations, indicating that only under certain conditions (particularly, at CdCl2 50 μM), this parameter can be used to estimate plant tolerance to Cd toxicity. TI was efficiently able to segregate tomato cultivars with similar performance (based on the total dry weight of plants), and such segregation was optimized when the hydroponic solution contained from 25 to 50 μM CdCl2. Within this range, data pointed at 35 μM CdCl2 as the best concentration to be employed in studies related to the tomato tolerance/sensitivity to Cd toxicity. In conclusion, TI proved to be a reliable estimator of tolerance degree to Cd exposure in genetically distinct tomato accessions. Moreover, TI can be used for this same purpose in plants under other HM-induced stresses.

Cadmium (Cd) is a heavy metal highly toxic to plants and human and animal health. The increased concentration of this metal in the environment in recent decades is the result of anthropogenic activities that include the production of mineral fertilizers, pesticides, intense mining, waste disposal, and foundries. Cd accumulation is known to induce oxidative stress in plant cells due to overproduction of reactive oxygen species, which may result in severe damage at the cellular level, ultimately impairing plant growth and productivity. In response to such stress, different molecules having enzymatic or nonenzymatic actions contribute to mitigate plant cellular damage and balance redox homeostasis in plant cells. This chapter aims to summarize current knowledge about the prospecting of important components of the molecular mechanisms associated with antioxidant machinery in plant response and tolerance to Cd toxicity. Insights into antioxidant response regulation, which includes hormones, signaling molecules, transcription factors, and microRNAs, are also presented.

RESUMO: Com o intuito de avaliar os efeitos da antibioticoterapia no crescimento de plantas micropropagadas de abacaxizeiros, bem como na comunidade bacteriana endofítica da espécie, realizaram-se análises moleculares. Verificou-se a presença de endófitos no interior das microplantas, mesmo após 30 dias de cultivo em meio de cultura MS, suplementado com diferentes antibióticos, e analisou-se o crescimento da parte aérea e radicular das microplantas. Decorrido o período de 30 dias de cultivo, constatou-se ainda a presença de bactérias endofíticas, no entanto, as microplantas apresentaram acentuada redução no crescimento da parte aérea e radicular, evidenciando assim a influência da microbiota endofítica no crescimento das microplantas in vitro e a importância da manutenção do equilíbrio endofítos/microplanta. ABSTRACT: This research aimed to evaluate the antibiotic therapy effects in the growing of micropropagated pineapple plants as well as in the community of the endophytic bacterial of the species. It was performed molecular analyzes and verified the presence of endophytes within microplants even after 30 days of culture on MS medium supplemented with different antibiotics and analyzed the development growth of shoots and roots of microplants. After the period of 30 days of cultivation, even being checked the presence of endophytic bacteria, it was verified that the microplants showed reduction of the growing of shoots and roots, thereby demonstrating the influence of in vitro endophytic microorganisms in the development of microplants, and the importance of maintaining it in equilibrium with endophytes/ microplants.

The in vitro propagation is a technique that is used for the large-scale generation of stable genotypes that are free of disease. Satisfactory propagation has been obtained using Bactris gasipaes Kunth through the direct in vitro regeneration of adventitious buds and somatic embryos, which is likely because of the pluri—and totipotency of the preprocambial cells, which reduces the probability of genetic instability. The consequences of the prolonged period of in vitro cultivation of perennial species such as the peach palm are not clear, as well as the senescence process has only been investigated in species originating from callus structures. The senescence of peach palm clones established and cultivated in vitro for 8 years through direct morphogenic methods (in vitro regeneration of adventitious buds without callus formation) was investigated in the leaves, roots and stem bases using histological, histochemical and ultrastructural analyses, in addition to the TUNEL reaction, to detect programmed cell death. These data from old cultures (8 years cultured) were compared to similar data from plants of the same species that had been established and cultivated in vitro for 1 year (young cultures). These analyses demonstrated the existence of intensive programmed cell death in the various tissues of the old cultures. The in vitro cultivation of peach palm for long periods promoted generalized senescence and probable aging of clones.

Nodal segments from secondary branches of saplings of Phyllostachys bambusoides were inoculated in MS medium to assess the in vitro morphogenic response of leaf sheath through the induction to callogenesis by Picloram (4-amino-3,5,6-trichloropicolinic acid) at different concentrations of carbohydrate under the same conditions with presence or absence of luminosity. In our experiment, secondary explants were kept in MS medium containing 8.0 mg·L−1 of Picloram for the callus formation. Calluses were transferred in MS medium supplemented with sucrose, fructose and glucose (control, 2%, 4% and 6%). Results show that Picloram induced the callogenesis in leaf sheath. The secondary embryogenesis was formed in yellow-globular callus. The sucrose as carbohydrate source in the absence of light was more efficient to induce rhizogenesis. Glucose was more efficiency in the presence of light. Callogenic induction and further embryogenesis evidenced the competence and determination of leaf sheath cells.

SummaryEucalyptus cloeziana is a species of great commercial interest due to the technical characteristics of its wood. However, the expansion of areas planted is limited by difficulties encountered with its clonal propagation. The objective of this study was to develop a method for cloning select adult trees of this species by a micropropagation technique. Epicormic shoots were induced in branches of adult trees and were viable as explants for in vitro establishment. Shoots were multiplied in vitro using Woody Plant Medium (WPM) culture supplemented with 6-benzylaminopurine (BA) and α-naphthaleneacetic acid (NAA) growth regulators. The optimum concentration of these for promoting proliferation of shoots was genotype-dependent. The best multiplication results were obtained with BA concentrations greater than 0.60 mg L–1 combined with 0.10 mg L–1 NAA for adult tree genotypes numbered 03 and 13, while for tree 05 the optimal result was found for the shoots cultured in culture medium free of the growth regul...

Peach palm (Bactris gasipaes Kunth.) cropping is an excellent alternative to native species exploitation; nevertheless, the problems with seed germination and conventional propagation justify the use of in vitro culturing. Aiming to asses TDZ pulsing effect on B. gasipaes morphogenesis, explants obtained from unarmed microplants were maintained in two treatments, half of them in MS free medium (without growth regulator) and the other half in MS with TDZ (0.36 μM). Both groups were transferred to growth regulator-free MS medium following 14 days of culture. After 84 days of culture, TDZ pulsing increased the growth and development of the shoots, restricted the growth and development of the roots, with no influence on adventitious bud induction or somatic embryogenesis. Furthermore, development of prickles, thickening of roots and chlorotic leaves were noted under TDZ pulsing. Leaf sheath histological analysis showed an epidermal origin and no vascularization of these prickles.

Xenia, the transmission of traits from the pollinizer to the female's tissues, is a phenomenon hitherto unknown in tomatoes. Here, we describe xenia effects on the seeds and fruits of Solanum lycopersicum, the tomato, elicited by S. galapagense. The wild tomatoes, such as S. galapagense, have highly pilose fruit surface and minute seeds, unlike the domesticated species. Crossings between S. galapagense (pollinizer) and two large-seeded, glabrous cultivars of S. lycopersicum (females) tested the former's ability to raise the trichome density and trichome-to-1000-cell ratio and to reduce the seed weight in the latter's fruits. Selfed fruits of the two cultivars, Micro-Tom and Pusa Ruby, were compared to the crossed fruits. The pollen of S. galapagense was able to raise pilosity and to reduce seed weight in the crossed fruits of both cultivars, but with different magnitudes: seed reduction was more intense in Pusa Ruby, while pilosity increase was greater in Micro-Tom, both of which characterize xenia. Pilosity increase is not completely dependent on variation in epidermal cell density, which displayed no xenia effect. The difference between the maternal cultivars in the magnitude of pilosity increase may be due to the higher dilution of a putative male chemical signal (either hormone or RNA) in the larger fruits of Pusa Ruby. However, one cannot use the signal diffusion hypothesis to explain the xenia effects on seed weight.

O Eucalyptus cloeziana se destaca pelas propriedades tecnológicas da sua madeira, principalmente em razão da sua durabilidade, densidade e resistência. Entretanto, essa espécie apresenta limitações quanto ao enraizamento adventício de estacas, dificultando a obtenção de mudas clonais e o avanço nos programa de melhoramento da espécie. Nesta perspectiva, o presente trabalho teve por objetivo avaliar a micropropagação de E. cloeziana a partir de materiais juvenis e adultos como uma técnica para a propagação da espécie. Para tanto, o trabalho foi dividido em quatro partes. No primeiro estudo, estabeleceu-se um protocolo de organogênese indireta de E. cloeziana a partir de hipocótilos e cotilédones. No segundo estudo avaliou-se o resgate de matrizes adultas de E. cloeziana através da indução de brotações epicórmicas em megaestacas. No terceiro estudo definiu-se um protocolo de micropropagação via proliferação de gemas axilares de matrizes adultas de E. cloeziana. Por último, no quarto estudo avaliou-se o rejuvenescimento in vitro de matrizes adultas de E. cloeziana por meio da micropropagação via proliferação de gemas axilares e a microestaquia, a partir das matrizes rejuvenescidas in vitro,para comprovar a viabilidade do cultivo in vitro como alternativa de propagação da espécie. A organogênese indireta de E. cloeziana mostrou-se possível e dependente do tipo de explante, dos reguladores de crescimento, suas concentrações e combinações utilizadas nas diferentes fases de morfogênese. As brotações adventícias foram micropropagadas e aclimatizadas com sucesso, obtendo-se mudas clonais de E. cloeziana. No resgate das matrizes adultas de E. cloeziana ocorreu maior indução de brotações epicórmicas para as megaestacas coletadas na época do ano com maior pluviosidade e temperatura. O diâmetro médio das megaestacas, compreendido entre 2,0 e 5,0 cm, correspondeu ao mais adequado para a obtenção de maior número de brotações epicórmicas no resgate das matrizes adultas de E. cloeziana. O protocolo de micropropagação das matrizes adultas de E. cloeziana foi estabelecido com sucesso, utilizando como explantes, brotações epicórmicas induzidas nas megaestacas. A multiplicação in vitro das microcepas foi realizada com êxito no meio de cultura WPM suplementado com BAP e ANA, cujas concentrações variaram entre os genótipos. Os tratamentos de \"pulse\" com GA3 não foi adequado para promover o alongamento in vitro das brotações, o qual foi obtido coma redução da concentração do BAP (0,1 mg L-1). A aclimatização e o enraizamento ex vitro das microestacas foi realizada com sucesso nos miniestufas, garantindo a obtenção de mudas clonais das matrizes adultas de E. cloeziana para a composição de um microjardim clonal. As microcepas das árvores matrizes de E. cloeziana apresentaram diferentes taxas de multiplicação in vitro, apresentando especificidades dos materiais genéticos à micropropagação. Os resultados da microestaquia das matrizes rejuvenescidas in vitro de E. cloeziana corroboraram as evidências de rejuvenescimento desses genótipos durante a micropropagação. Além disso, constatou-se que outros fatores, além da maturidade, podem estar atuando diretamente na recalcitrância do E. cloeziana ao enraizamento adventício. Dessa forma, comprovou-se a importância da micropropagação como uma ferramenta para a clonagem de E. cloeziana, abrindo perspectivas para investigações futuras para otimizar os métodos de propagação da espécie. Eucalyptus cloeziana has importance for its wood technologic characteristics, mainly the durability, density and resistance. Moreover, this species has limitations on adventitious rooting of cuttings, having difficulties to obtain clonal seedlings and to advance in the improvement programs. In this perspective, the present work aimed to evaluate the E. cloeziana micropropagation by juvenile and mature explants as a technique for propagation this specie. Therefore, the work was divided into four basic studies. The first study was the establishment of the protocol to indirect organogenesis to E. cloeziana hypocotyls and cotyledons. In the second study evaluated the rescue of E. cloeziana adult matrices for epicormic shoots induction in crow branches. In the third study was definite a micropropagation protocol by axillary branching of E. cloeziana adult matrices. Finally, in the fourth study was evaluated the in vitro rejuvenation of E. cloeziana adult matrices to micropropagation by axillary branching and the micro-cutting technique of in vitro rejuvenated matrices to prove the in vitro culture viability to the propagation of this specie. The indirect organogenesis E. cloeziana was dependent of explant type and growth regulator and its concentration used in the different morphogenesis phases. The adventitious shoots were multiplicities and acclimatized with success to obtain E. cloeziana clonal seedlings. The vegetative rescue results of E. cloeziana adult matrices showed a higher induction epicormic shoots from branches collected in warmer and rain season. The medium diameter between 2.0 and 5.0 cm was considered the better to obtain higher epicormic shoots number in vegetative rescue. The micropropagation protocol of E. cloeziana adult matrices was realized with success using epicormic shoots, induced in the branches, like explants. The shoots in vitro multiplication was realized on WPM medium culture, supplemented with BA and NAA. The better growth regulators concentrations were different for each genotype. Treatments pulse with GA3 was not suitable to promote the elongation of shoots in vitro, which was obtained by the BA concentration reduction at 0.1 mg L-1. The in vitro shoots acclimatization and ex vitro rooting was performed in mini-incubators with success and it permit to obtain clonal seedlings from E. cloeziana adult matrices to form a clonal micro-garden. The shoots of E. cloeziana adult matrices showed different in vitro multiplication rates with specific-genotype responses to micropropagation. The micro-cutting technique results of E. cloeziana adult matrices provide evidence that occurred in vitro rejuvenation of these genotypes, during the micropropagation. Therefore, the nursery results showed that other factors, not only maturation, can be involved in the adventitious recalcitrance of E. cloeziana. In conclusion, the importance micropropagation like a biotechnological tool to propagation of E. cloeziana was proved and opened important perspectives for future investigations to optimize the propagation methods for this specie.

O Pinus elliotti representa o principal produtor atual de exploração de resina no setor florestal brasileiro. Recentemente, plantios de P. elliottii X P. caribaea vêm se destacando, principalmente, pela sua maior produtividade em biomassa. Além disto, a resina do híbrido apresenta características químicas semelhantes aos seus parentais. Porém, poucas são as informações quanto a estaquia de espécies do gênero Pinus, e se focarmos na propagação de árvores adultas, tal carência é ainda maior, principalmente ao se considerar a dificuldade de rejuvenescimento/revigoramento do material genético. Neste contexto, o presente trabalho teve como objetivo geral avaliar o enraizamento adventício do P. elliottii var. elliottii e P. elliottii X P. caribaea adultos. Para tanto, o trabalho foi dividido em três diferentes estudos. O primeiro (Capítulo 2) avaliou o enraizamento adventício de estacas das matrizes adultas de P. elliottii e P. elliottii X P. caribaea no 5° estágio de enxertia seriada com e sem podas sucessivas, sob ação do AIB, talco com fungicida Cerconil® e terebentina. O segundo (Capítulo 3) foi baseado na avaliação do enraizamento adventício de estacas no 2° estágio de enxertia seriada de uma matriz adulta de P. elliottii var. elliottii submetida a um ano de podas sucessivas, sob ação do AIB, terebentina e paclobutrazol. Por sua vez, o terceiro estudo (Capítulo 4) consistiu na avaliação do enraizamento adventício de braquiblastos e brotos de duas matrizes adulta de P. elliottii e P. elliottii X Pinus caribaea, sob ação do AIB e paclobutrazol. Os resultados permitiram inferir que a sobrevivência e o enraizamento adventício aos diferentes tratamentos variaram de acordo com o genótipo e com as características morfológicas das estacas (grau de lignificação e tipo de estacas, brotos e braquiblastos). De maneira geral, os resultados evidenciaram a atuação das enxertias seriadas e das podas sucessivas na restauração da competência rizogênica das estacas dos brotos das matrizes adultas de P. elliottii e P. elliottii X P. caribaea, promovido pelo rejuvenescimento/ revigoramento parcial das matrizes. Além disto, a estaquia de braquiblastos mostrou ser uma ferramenta promissora para a propagação de espécies do gênero Pinus. Pinus elliottii is the main current resin extraction producer in the Brazilian forest sector. Recently, plantations of P. elliottii X P. caribaea play a great importance in the production systems mainly by its high biomass productivity. In addition, the hybrid resin has chemical characteristics similar to their parents. However, there is little information on obtaining clones, and considering the propagation of mature trees, this lack of information is even greater, mainly concerning the difficulty to achieve the rejuvenation/ reinvigoration of the genetic material. Based on theses information, the present work was aimed to evaluate the adventitious rooting of mature P. elliottii var. elliottii and P. elliottii X P. caribaea cuttings. Therefore, the work was divided into three basic studies. The first study (Chapter 2) was based on the evaluation of adventitious rooting of mature P. elliottii and P. elliottii X caribaea cuttings of grafts up five sequential grafting with and without pruning, under the action of AIB, talc with fungicide and turpentine. The second (Chapter 3) was based on the evaluation of adventitious rooting of mature P. elliottii cuttings of grafts up two sequential grafting with pruning, under the action of IBA, paclobutrazol and turpentine. The third (Chapter 4) evaluated the adventitious rooting of brachyblast and shoots of mature P. elliottii and P. elliottii X caribaea cuttings, under the action of IBA and paclobutrazol. Results showed that the cutting survival and root growth, under the action of different treatments, varied according to the genotype and morphological characteristics of the material (cutting lignifications and type, brachyblast or shoot). Overall, our results showed the performance of serial grafting and pruning on the restoration of rooting competence in P. elliottii and P. elliottii X P. caribaea stem cuttings, promoted by the rejuvenation of trees. Moreover, the cutting of brachyblast can be a promising tool for the propagation of Pinus species.