Cláudia Roberta Damiani

In vitro methods rely on costly chemical inputs, such as synthetic nutrients, prompting us to search for sustainable alternatives. This study evaluated wastewater generated from the cigarette butt (CB) recycling process as a potential growth stimulant additive for in vitro plant cultivation. Seeds of Brachiaria ruziziensis Germain & Evrard were sown on agar media containing increasing CB wastewater concentrations from 0 to 25% v/v (CB0 to CB25, respectively) under controlled conditions. Germination was monitored over 10 days, and functional and physiological traits of shoot and root systems were assessed at the end. Responses were concentration-dependent and consistent with hormesis. Low concentrations, particularly CB2, enhanced germination (92.2% vs. ~67% in CB0), shoot elongation (~6 vs. 3.4 cm), and total biomass (~47 vs. ~33 mg fresh weight), while maintaining total chlorophyll and increasing carotenoids (147.8 vs. 103.3 µg g⁻¹ FW) and chlorophyll a/b ratio (2.1 vs. 1.5). Contrarily, higher concentrations (≥CB10) reduced germination (47.6% at CB25), strongly inhibited root growth (0.5 cm at CB25), decreased total biomass (~19 mg at CB25), led to growth disorders, and reduced pigment stability. These inhibitory effects were associated with the accumulation of CB-derived compounds, including high nicotine levels and unbalanced nutrients. At low concentrations, coordinated root aerenchyma formation and modulation of stomatal density indicated anatomical plasticity under mild stress conditions, although their physiological significance remains to be clarified. Overall, CB recycling-derived wastewater can act as an effective growth stimulant for B. ruziziensis in vitro when applied at low concentrations, offering a potential alternative for plant biotechnology while contributing to waste valorization.

Zinc (Zn: 0–400 mg L⁻¹ zinc acetate), lead (Pb: 0–400 mg L⁻¹ lead acetate), and cadmium (Cd: 0–8 mg L⁻¹ cadmium chloride) tolerance in stem explants of Tocoyena brasiliensis Mart. from seeds collected in the Brazilian Cerrado were studied under controlled conditions. The explants showed a regular growth activity in a metal-free medium. All metals did not affect explant survival, except for 400 mg L⁻¹ Zn, which resulted in lethality. Shoot number was not affected by metal treatment, while shoot length and leaf number varied depending on the metal. Cd induced a gradual reduction in leaf number without affecting shoot length. Pb gradually reduced the shoot length at concentrations beyond 200 mg L⁻¹, while no effects were found in Zn concentrations from 0 to 200 mg L⁻¹. Pb and Zn induced leaf production at 50 mg L⁻¹, while a gradual reduction was observed with increasing concentration. Callus formation was not affected by Cd, while increasing Zn and Pb concentrations reduced this cell division and organization with Zn, showing drastic effects. Altogether, T. brasiliensis explants demonstrated high tolerance to Cd and Pb. However, further studies are needed to explore the phytoextraction capacity of this species at in vitro and planta levels.

Baru (Dipteryx alata Vogel) is a native tree plant, widely distributed in Brazil, and has a growth and development in acidic soils like Cerrado, indicating a probable tolerance to adverse soil conditions, such as the high concentration of metals and the acidic pH. Due to the lack of information about the tolerance of this species to metals and the possibility of being used in the recovery of degraded areas and/or in phytoremediation, this work was developed with the objective of evaluating the in vitro germination and growth capacity of baru in medium supplemented with different concentrations of aluminum, iron, and manganese, as well as through chemical analysis, to determine the concentration of metals accumulated in cultivated plants in these conditions. The treatments consisted in different concentrations of metals: aluminum, Al³⁺ (0, 3.5, 7.0, 10.5, 21.0, or 42.0 mg L⁻¹); iron, Fe³⁺ (0, 2.5, 4.9, 7.4, 14.7, or 29.4 mg L⁻¹); and manganese, Mn²⁺ (0, 0.4, 0.8, 1.2, 2.4, or 4.8 mg L⁻¹) added to the medium WPM. The tested values were based on using the lower concentration as the limit value, calculated based on risk to human health in accordance with CONAMA resolution 420/2009 for groundwater. At 60 days of cultivation, the percentage of germination, the average number of leaves, the length of the main root and the aerial part, the fresh and dry mass of the aerial part and the root system and the cations concentration Al³⁺, Fe³⁺ and Mn²⁺ in the plant biomass, were evaluated. The results showed that under the conditions in which the experiment was conducted, germination and in vitro growth of baru were not affected by the presence in high concentrations of any of the evaluated metals, with no differences in the percentage of germination and plant growth, as well as typical toxicity characteristics were not observed, such as changes in root morphology, chlorosis, or tissue oxidation. The absence of toxicity symptoms in baru plants, in the presence of Al³⁺, Fe³⁺, and Mn²⁺, indicate that the species is tolerant to these metals. The accumulation of Al³⁺ and Fe³⁺ in the plant biomass at the beginning of growth, simultaneously with the increase in the concentrations of these elements in the culture medium, indicates that this species can be used for phytoremediation, because it is a probable accumulator of these elements throughout its development, given the presence in significant concentrations of these elements also in the seeds.

The objectives of this study were to determine the optimal light conditions, agar concentration, and quantity of activated charcoal in asymbiotic media to improve the in vitro seed germination rate and early seedling development of the epiphytic orchids Dendrobium nobile Lindl. and Dendrobium phalaenopsis Fitzg. Two independent experiments with complete randomized designs were conducted. (1) Treatments were arranged in a split-plot scheme. Seeds in each sub-plot were exposed to one of four light conditions (dark, white fluorescent, red fluorescent + white fluorescent, or red fluorescent) and grown in one of four types of culture media (MS: Murashige and Skoog, ½ MS: half strength MS, K: Knudson C, and VW: Vacin and Went media). (2) Treatments were arranged in a 4 × 5 × 5 factorial scheme (four types of culture media: MS, ½ MS, K, and VW; five concentrations of agar: 0.0, 2.0, 4.0, 6.0, or 8 g L−1; and five concentrations of activated charcoal: 0.0, 1.5, 3.0, 4.5, or 6.0 g L−1). The highest germination rates and early seedling development were observed 45 days after seeding in the presence of white light for D. nobile and red + white light for D. phalaenopsis in MS and ½ MS culture media. Based on the findings of the present study, the use of MS and ½ MS culture media solidified with 4.0–8.0 g L−1 of agar and without activated charcoal is recommended for the optimal propagation of seeds and seedlings of these Dendrobium species.

Campomanesia adamantium (guavira), é frutífera nativa do Cerrado, encontrada em grande maioria no estado silvestre e apresenta limitações na propagação relacionada à recalcitrância das sementes. Considerando a ausência de manejo e tratos culturais, o estabelecimento da cultura in vitro a partir de material vegetativo está sujeito a altos índices de contaminação fúngica e bacteriana. Visando a propagação, objetivou-se avaliar a capacidade de multiplicação in vitro de guavira, utilizando segmentos caulinares retirados de plântulas da germinação in vitro. Foram desenvolvidos três experimentos, sendo avaliados o efeito de 5,0 µM de TDZ (thiadizurom), 1,0 µM de ANA (ácido naftaleno acético) e a combinação dos mesmos, bem como, o efeito isolado de BAP (6-benzilaminopurina) e 2iP (2-isopentenil adenina), nas concentrações de 0; 2,5; 5,0; 7,5 e 10 mg L-1. Os resultados obtidos demonstraram que o uso de 5,0 µM de TDZ aumentou o comprimento das brotações, número de gemas e taxa de multiplicação, enquanto a combinação de TDZ e ANA exerceu um efeito negativo sobre o crescimento das brotações, número de folhas e taxa de multiplicação. O cultivo dos explantes em meio contendo BAP aumentou o número de brotações, ao aumento da concentração do regulador, entretanto, reduziu o comprimento das brotações.

In germinating seeds under unfavorable environmental conditions, the mobilization of stores in the cotyledons is delayed, which may result in a different modulation of carbohydrates balance and a decrease in seedling vigor. Tall fescue (Festuca arundinacea Schreb.) caryopses grown at 4°C in the dark for an extended period in complete absence of nutrients, showed an unexpected ability to survive. Seedlings grown at 4°C for 210 days were morphologically identical to seedlings grown at 23°C for 21 days. After 400 days, seedlings grown at 4°C were able to differentiate plastids to chloroplast in just few days once transferred to the light and 23°C. Tall fescue exposed to prolonged period at 4°C showed marked anatomical changes: cell wall thickening, undifferentiated plastids, more root hairs and less xylem lignification. Physiological modifications were also observed, in particular related to sugar content, GA and ABA levels and amylolytic enzymes pattern. The phytohormones profiles exhibited at 4 and 23°C were comparable when normalized to the respective physiological states. Both the onset and the completion of germination were linked to GA and ABA levels, as well as to the ratio between these two hormones. All plants showed a sharp decline in carbohydrate content, with a consequent onset of gradual sugar starvation. This explained the slowed then full arrest in growth under both treatment regimes. The analysis of amylolytic activity showed that Ca²⁺ played a central role in the stabilization of several isoforms. Overall, convergence of starvation and hormone signals meet in crosstalk to regulate germination, growth and development in tall fescue.

Campomanesia adamantium (Cambess.) O. Berg seeds (guavira) are recalcitrant and rapidly lose viability upon removal from the fruit, making difficult the long-term storage. In vitro germination could be used as an important tool to overcome the issues related to this short viability. It might help seed conservation and species propagation. The purpose of this study was to evaluate in vitro germination of guavira seeds collected from different sites and stored under different conditions. Also, the sowing of these seeds in MS medium supplemented with different concentrations of gibberellic acid (GA3) was evaluated. Seeds from the local garden were treated with: 0, 1.0, 2.0, 3.0, or 4.0 mg L-1 GA3. Seeds from a local farmer’s market were treated with: 0, 2.5, 5.0, 7.5 or 10 mg L-1 GA3. We evaluated the germination rate, the average length of the shoot and main root, and the number of leaves. The C. adamantium seeds were sown immediately after harvest and treated with GA3, regardless concentration, increased germination rate by at least 10%, whereas 1.0 mg L-1 GA3 resulted in 100% germination. The shoot length increased linearly with increasing concentration of the growth regulator. Different concentrations of GA3 had no effect on the development of the main root and leaves. Seeds acquired from a local farmer’s market showed lower germination rate than those sown immediately after harvesting, and did not differ in the rate of germination under different treatments with GA3. Furthermore, around 25% of those seedlings had abnormal leaf morphology. C. adamantium seeds stored at 4°C and -20°C for 60 days did not germinate successfully, suggesting that seeds under cold storage conditions cannot be used for germplasm purposes. Key words: Guavira, Cerrado, Myrtaceae, temperature.

Este trabalho foi realizado com o objetivo de avaliar a aclimatização e o crescimento de plântulas micropropagadas de mirtileiro (Vaccinium ashei) cv. Climax, em função do substrato e da cobertura plástica, durante os meses de abril a dezembro de 2008. Foram utilizados três substratos (casca de arroz carbonizada + Húmus Fértil®, Plantmax® + vermiculita e solo + serragem jovem de Pínus) e dois sistemas de cobertura (com e sem cobertura plástica sobre as plântulas). As plântulas, acondicionadas em sacos plásticos com os respectivos substratos e sistemas de cobertura, permaneceram em casa de vegetação com temperatura controlada, por 30 dias. Após, permaneceram por 60 dias sem controle ambiental e, em seguida, foram transferidas para telado. A partir de 30 dias, foram avaliados a percentagem de sobrevivência e o incremento de altura das plântulas. Ao término do experimento, foi avaliada a massa fresca e seca da parte aérea e da raiz das plântulas. A percentagem de sobrevivência das plântulas de mirtileiro em substrato Plantmax® + vermiculita é igual quando utilizada ou não a cobertura plástica. O uso da cobertura plástica não foi eficiente para incrementar a altura média das plântulas nos substratos Plantmax® + vermiculita e solo + serragem jovem. A maior massa seca de parte aérea foi obtida com o uso de Plantmax® + vermiculita sem cobertura plástica sobre as plântulas. Plantmax® + vermiculita com e sem cobertura plástica proporcionam maior massa seca radicular que os demais substratos e respectivos sistemas de cobertura, porém Plantmax® + vermiculita sem cobertura plástica é superior a Plantmax® + vermiculita com cobertura plástica. De acordo com os resultados obtidos, conclui-se que o melhor substrato e sistema de cobertura para a aclimatização e o crescimento de plântulas de mirtileiro 'Climax' são Plantmax® + vermiculita sem cobertura plástica.