Marcos Pereira Marinho Aidar

Novo método enzimático rápido e sensível de extração e dosagem de amido em materiais vegetais

A new rapid and sensitive enzymatic method for extraction and quantification of starch in plant material). In this work we compare methods normally used for starch determination in plant materials. The comparison between chemical (McCreadys method) and an enzymatic method proposed here showed that although McCreadys method is appropriate for most plant materials, in certain cases where cell wall polysaccharides (pectins and hemicelluloses) are present, the results may be significantly altered. However, using the enzymatic method described here afforded accurate estimation of starch content in such tissues. The enzymatic method proposed in this work is an affordable option for precise determination of starch contents in several plant tissues.

Impact of point source pollution on nitrogen isotope signatures (δ15N) of vegetation in SE Brazil

This study presents novel evidence that 15N natural abundance can be used as a robust indicator to detect pollutant nitrogen in natural plant communities. Vegetation from the heavily polluted industrial area of Cubatão in São Paulo State, SE Brazil, was strongly 15N depleted compared to plants at remote sites. Historic herbarium samples from Cubatão were significantly less 15N depleted than extant plants, indicating that 15N depletion of vegetation is associated with present-day nitrogen pollution in Cubatão. The heavy load of nitrogenous atmospheric pollutants in Cubatão provides a nitrogen source for plants, and strongly 15N depleted air NH3 is likely to contribute to plant and soil 15N depletion. Epiphytic plants from Cubatão were extremely 15N depleted (average –10.9‰) contrasting with epiphytes at remote sites (averages –1.0‰ and –3.0‰). Nitrogen isotope composition of vegetation provides a tool to determine input of pollutant nitrogen into plant communities. The strong isotopic change of epiphytes suggests that epiphytes are particularly sensitive biomonitors for atmospheric pollutant nitrogen.

Elevated CO2 atmosphere promotes plant growth and inulin production in the cerrado species Vernonia herbacea

Carbon allocation in biomass is an important response of plants to the increasing atmospheric [CO2]. The effects of elevated [CO2] are scarcely reported in fructan-accumulating plants and even less in tropical wild species storing this type of carbohydrate. In the present study, the effects of high [CO2] atmosphere was evaluated on growth, biomass allocation and fructan metabolism in Vernonia herbacea (Vell.) Rusby, an Asteraceae from the Brazilian cerrado, which accumulates inulin-type fructans in the underground organs (rhizophores). Plants were cultivated for 120 days in open-top chambers (OTCs) under ambient (~380 μmol mol–1), and elevated (~760 μmol mol–1) [CO2]. Plant growth, photosynthesis, fructan contents, and the activities of fructan metabolising enzymes were analysed in the rhizophores at Time 0 and 15, 30, 60, 90 and 120 days. Plants under elevated [CO2] presented increases in height (40%), photosynthesis (63%) and biomass of aerial (32%) and underground (47%) organs when compared with control plants. Under elevated [CO2] plants also presented higher 1-SST, 1-FFT and invertase activities and lower 1-FEH activity. Although fructan concentration remained unchanged, fructan productivity was higher in plants maintained under elevated [CO2], due to their higher rhizophore biomass. This is the first report on the effects of elevated [CO2] on a plant species bearing underground organs that accumulate fructans. Our results indicate that plants of V. herbacea can benefit from elevated atmospheric [CO2] by increasing growth and carbon allocation for the production of inulin, and may contribute to predict a future scenario for the impact of this atmospheric condition on the herbaceous vegetation of the cerrado.

Aspects of arbuscular mycorrhizal fungi in an atlantic forest chronosequence parque estadual turístico do Alto Ribeira (petar), SP

Foi levantada a ocorrencia de colonizacao por micorriza nas raizes das especies arboreas que dirigem a sucessao secundaria sobre solo calcario em uma area localizada no Parque Estadual Turistico do Alto Ribeira (PETAR), sudeste do Estado de Sao Paulo, Brasil. O levantamento fitossociologico foi realizado em tres areas justapostas correspondentes a diferentes idades de abandono apos cultivo de subsistencia sobre um solo calcario: Fase Inicial com 15 anos; Fase Intermediaria com 25 anos e Fase Tardia com mais de 36 anos sem corte raso. O inventario indicou a predominância de especies da familia das leguminosas, especialmente Piptadenia gonoacantha (Mimosoideae) nos estagios iniciais de sucessao. A ocorrencia de colonizacao por micorriza nas raizes das especies arboreas decresceu ao longo da sucessao durante a estacao com menos chuva (inverno). Durante o periodo de verao, estacao mais umida, a colonizacao nao apresentou diferencas significativas entre as fases de sucessao. A colonizacao por micorriza nas raizes apresentou correlacao com a ocorrencia de diferentes estrategias de regeneracao entre as especies arboreas: positivamente com o aumento de ocorrencia de especies pioneiras e negativamente com especies secundarias tardias. A colonizacao apresentou tambem correlacao negativa com o conteudo de materia orgânica e saturacao de bases no solo. Foram identificadas 25 especies de fungos micorrizicos arbusculares pertencentes a quatro generos, e seis especies apenas foram identificadas ao nivel de genero. A especie Glomus etunicatum Becker & Gerd. representou 10 % dos esporos encontrados na rizosfera das amostras analisadas, tendo ocorrido em todas as fases sucessionais e estacoes. O genero Glomus representou 57% do total de esporos. Os indices de diversidade para a comunidade de fungos micorrizicos indicaram os seguintes valores: H’ = 2.3, J’ = 0.97 e R = 4.12. Estes resultados sao importantes contribuicoes para um melhor conhecimento da biodiversidade da Mata Atlântica e podem ser decisivos no sucesso de acoes para a reabilitacao de areas degradadas neste que e um dos biomas mais ameacados do planeta.

Atlantic Forest succession over calcareous soil, Parque Estadual Turístico do Alto Ribeira - PETAR, SP

The forest succession after abandonment of slash-and-burn agriculture over calcareous soil in Brazilian Atlantic Forest was assessed. This is one of the worlds most threatened Biome, with only 8% remaining. The study area is located over calcareous soil inside the Alto Ribeira Touristic State Park (PETAR), southeast Brazil. The phytossociological survey showed a successional pattern dominated by species of Leguminosae, especially Piptadenia gonoacantha (Mart.) J.F. Macbr. This species occurs in calcareous soils as a substitute of Tibouchina pulchra (Cham.) Cogn. (Melastomataceae) that is the most usual dominant tree species in early succession over acidic soil, which is the most common situation in this Biome. These results are important for a better understanding of Neotropical forest biodiversity and characterize a unique genetic bank in this highly endangered Biome. They are also decisive to support actions regarding rehabilitation of degraded lands and a potential tool for Neotropical forest sustainable management, both inside and around the conservation unit.

Carbon sequestration in the rain forest: alternatives using environmentally friendly biotechnology

Com o recente aumento na concentracao atmosferica de CO2 e o consequente aumento nas medias de temperatura, as alteracoes ambientais previstas poderiam causar danos a civilizacao na forma em que conhecemos. Como consequencia desses previsoes, a necessidade de sequestrar carbono esta se tornando urgente e uma das opcoes que temos e o uso do potencial que as florestas tropicais tem de assimilar CO2 atraves da fotossintese. No entanto, se considerarmos o uso de plantas para aumentar o sequestro de carbono, havera um problema que e o fato de muitas especies vegetais aclimatarem, o que significa uma inibicao na assimilacao de CO2 pela producao de acucares. No presente artigo, propomos que algumas rotas bioquimicas poderiam ser alteradas em plantas de forma a controlar a fotossintese, metabolismo de carboidratos e tambem a sintese de celulose. Com isso talvez se pudesse aumentar o sequestro de carbono. Dentre as tecnologias disponiveis, aquela que apresenta um rapido desenvolvimento recente e o controle do metabolismo atraves de alteracoes no controle genetico de vias metabolicas. Ainda que isto seja controverso, o tempo esta correndo e de acordo com as previsoes, nos podemos ter um pouco mais de 50 anos antes que a concentracao de CO2 atmosferico dobre. Considerando que ja conhecemos alguns genes que poderiam ser alvo de transformacoes de plantas e que estas tecnicas estao melhorando com grande velocidade, neste trabalho nos discutimos algumas das formas ambientalmente saudaveis para abordar o problema.

Dinâmica da produção e decomposição da serapilheira do araribá (Centrolobium tomentosum Guill. ex Benth. - Fabaceae) em uma mata ciliar, Rio Jacaré-Pepira, São Paulo

This study was conducted in a remaining riparian forest (42 ha) in the Jacare-Pepira river, where Centrolobium tomentosum Guill. ex Benth., an early secondary and deciduous species, is the most important tree in the seasonal semideciduous forest. C. tomentosums litter production reached 4.2 kg.ind-1, with two peaks of leaf shedding (January/February _ 25.1% and July/August _ 52.3%) representing an input to soil surface of (g.ind.1 year1): 74.7 N; 6.1 P; 29.0 K; 73.9 Ca; 25.8 Mg and 14.1 S. Leaf litter produced takes 19.5 months for decomposition, which is strongly seasonal. The quality and quantity of C. tomentosums litter indicate its potentially important role in the functional and structural recovery of riparian forests in the Sao Paulo State.

Fine root biomass and root length density in a lowland and a montane tropical rain forest, SP, Brazil

Raizes finas, <2 mm de diâmetro, sao as principais responsaveis pela absorcao de agua e nutrientes e, portanto, tem um papel central nos ciclos carbono, agua e nutrientes, desde o nivel da planta ate o ecossistemico. A densidade do comprimento radicular (DCR), a biomassa de raizes finas (BRF) e a distribuicao vertical de raizes finas (DVR) no perfil do solo tem sido utilizados como bons descritores da eficiencia no uso de recursos e de estocagem de carbono no solo. Ao longo de gradientes altitudinais, a diminuicao da temperatura e da radiacao solar (dependendo da frequencia de eventos de neblina) podem reduzir as taxas de decomposicao e disponibilidade de nutrientes, o que poderia estimular o aumento do investimento das raizes finas para maximizar a absorcao de agua e nutrientes. O presente estudo avaliou a variacao sazonal de parâmetros radiculares nas florestas ombrofilas densas de Terras Baixas (FODTB) e Montana (FODM) na Mata Atlântica. A hipotese foi a de que o investimento em BRF e DCR seria maior na FODM, o que poderia maximizar a eficiencia na absorcao de recursos. A BRF e a DCR foram maiores na FODM em ambas as estacoes, especialmente na profundidade de 0-5 cm. A BRF total nos primeiros 30 cm de solo na FODTB foi significativamente menor (334 g.m-2 na estacao seca e 219 g.m-2 na chuvosa) do que na FODM (875 e 451 g.m-2 nas estacoes seca e chuvosa, respectivamente). Na profundidade de 0-5 cm em ambas as altitudes, a DCR aumentou da estacao seca para chuvosa independentemente de variacoes na BRF. Apesar da relevância da BRF para descrever processos relacionados a dinâmica de carbono, a variacao da DCR entre estacoes, independente de variacoes na BRF, indica que a DCR e um melhor descritor para estudos caracterizando o potencial de absorcao de agua e nutrientes na Floresta Atlântica. As diferencas da DCR entre altitudes dentro do contexto de uso de recursos devem ser consideradas em estudos sobre estabelecimento, crescimento de plântulas e dinâmica de populacoes na Floresta Atlântica. No nivel ecossistemico, as variacoes sazonais da DCR podem aumentar nosso entendimento sobre o funcionamento da Floresta Atlântica em termos de fluxos biogeoquimicos em um possivel cenario de mudancas climaticas e ambientais.Fine roots, <2 mm in diameter, are responsible for water and nutrient uptake and therefore have a central role in carbon, nutrient and water cycling at the plant and ecosystem level. The root length density (RLD), fine root biomass (FRB) and vertical fine root distribution (VRD) in the soil profile have been used as good descriptors of resource-use efficiency and carbon storage in the soil. Along altitudinal gradients, decreases in temperature and radiation inputs (depending on the frequency of fog events) may reduce decomposition rates and nutrient availability what might stimulate plants to invest in fine roots, increasing acquisition of resources. We evaluated the seasonal variation of fine root parameters in a Lowland and Montane forest at the Atlantic Rain Forest. We hypothesized that, due to lower decomposition rates at the Montane site, the FRB and RLD at soil surface will be higher in this altitude, which can maximize the efficiency of resource absorption. FRB and RLD were higher in the Montane forest in both seasons, especially at the 0-5 layer. At the 0-5 soil layer in both sites, RLD increased from dry to wet season independently of variations in FRB. Total FRB in the top 30 cm of the soil at the Lowland site was significantly lower (334 g.m-2 in the dry season and 219 g.m-2 in the wet season) than at the Montane forest (875 and 451 g.m-2 in the dry and wet season, respectively). In conclusion, despite the relevance of FRB to describe processes related to carbon dynamics, the variation of RLD between seasons, independently of variations in FRB, indicates that RLD is a better descriptor for studies characterizing the potential of water and nutrient uptake at the Atlantic Rain Forest. The differences in RLD between altitudes within the context of resource use should be considered in studies about plant establishment, seedling growth and population dynamics at the Atlantic Rain Forest. At the ecosystem level, RLD and it seasonal variations may improve our understanding of the Atlantic rain forest functioning in terms of the biogeochemical fluxes in a possible scenario of climate change and environmental changes.

Changes in plant functional traits and water use in Atlantic rainforest: evidence of conservative water use in spatio-temporal scales

Key messageRelationship between sap flow and functional traits changes with altitude and changes in water availability can impose a conservative water use in woody species of tropical rainforest.AbstractUsing a trait-based approach, we have identified that tropical trees are vulnerable to decreases in water availability, especially in montane areas, where higher radiation and vapor pressure deficits lead to higher water loss from trees. Changes to functional traits are useful descriptors of the response of species to variation in resource availability and environmental conditions. However, how these trait-environment relationships change with altitude remains unclear. We investigated changes in xylem sap flow along an altitudinal variation and evaluated the contribution of morphological traits to total plant water use. We hypothesize that (1) at the Montane forest, plant species will show a more conservative water use and (2) seasonally, there will be a much greater increase in conservative water use during the dry season at the Lowland site, since the climate conditions in the Montane site impose constraints to water use throughout the year. Remarkably, although water is assumed to be a non-limiting resource for Atlantic rainforest in general, we observed ecophysiological adjustments for more conservative water use in Montane forest. Our findings demonstrate that changes to water supply and demand as determined by rainfall, VPD and soil water storage can impose restrictions to water loss which differ across spatio-temporal scales. We suggest that the next steps for research in Montane forest should focus on traits related to hydraulic failure and carbon starvation to address the question whether the higher conservative water use observed at the Montane Forest translates into a higher or lower susceptibility to intensification of drought which might arise due to climate change.

Ozone-induced responses in Croton floribundus Spreng. (Euphorbiaceae): metabolic cross-talk between volatile organic compounds and calcium oxalate crystal formation.

Here, we proposed that volatile organic compounds (VOC), specifically methyl salicylate (MeSA), mediate the formation of calcium oxalate crystals (COC) in the defence against ozone (O3) oxidative damage. We performed experiments using Croton floribundus, a pioneer tree species that is tolerant to O3 and widely distributed in the Brazilian forest. This species constitutively produces COC. We exposed plants to a controlled fumigation experiment and assessed biochemical, physiological, and morphological parameters. O3 induced a significant increase in the concentrations of constitutive oxygenated compounds, MeSA and terpenoids as well as in COC number. Our analysis supported the hypothesis that ozone-induced VOC (mainly MeSA) regulate ROS formation in a way that promotes the opening of calcium channels and the subsequent formation of COC in a fast and stable manner to stop the consequences of the reactive oxygen species in the tissue, indeed immobilising the excess calcium (caused by acute exposition to O3) that can be dangerous to the plant. To test this hypothesis, we performed an independent experiment spraying MeSA over C. floribundus plants and observed an increase in the number of COC, indicating that this compound has a potential to directly induce their formation. Thus, the tolerance of C. floribundus to O3 oxidative stress could be a consequence of a higher capacity for the production of VOC and COC rather than the modulation of antioxidant balance. We also present some insights into constitutive morphological features that may be related to the tolerance that this species exhibits to O3.