Ângela Maria Soares

Ecophysiological and anatomical changes due to uptake and accumulation of heavy metal in Brachiaria decumbens

The growth and developmental characteristics of grasses and their high biodiversity make such plants suitable for remediation of areas contaminated by heavy metals. Nevertheless, heavy metal toxic effect on the plants may cause alteration in their metabolic pathways, such as photosynthesis, respiration, and growth, modifying plant anatomy. This work aimed to evaluate the effect of levels of soil contamination (0, 7.5 % and 15 % m3 m-3) on biomass production, on photosynthetic characteristics and on anatomical changes in roots and leaves of brachiaria (Brachiaria decumbens Stapf.). After seeds were planted, seedlings were uprooted and replanted in vases containing soil at different contamination levels, being left to rest for 120 days. At the end of that time, plants presented reduced yield of root and shoot dry matter, contents of chlorophyll a, chlorophyll b, total chlorophyll and potential photosynthesis with increased of soil contamination. The cell layers of endodermis and exodermis in the root tissues and the cell walls of the xylem and cortical parenchyma all thickened as contamination increased. In the leaf tissues, the adaxial and abaxial epidermis presented increased thickness while the leaf blade presented reduced thickness as contamination increased with consequent change in the root growth rate. In general, the effects of heavy metal increased with the metal concentration. Some results indicate that B. decumbens seems to have some degree of heavy metal tolerance.

Alterações anatômicas e fisiológicas em Setaria anceps Stapf ex Massey e Paspalum paniculatum L. sob condições de déficit hídrico

Both Setaria anceps (setaria) and Paspalum paniculatum (paspalo) species are tolerant to soil drought water deficiency and flooding. The aim of this work was evaluate anatomical, ecophysiological and metabolic alterations on setaria and paspalo leaves and roots when submitted to soil water deficit conditions. Eleven days after the beginning of water restriction, few variations were observed in density and size of stomata in setaria, but there was decreasing in thickness of mesophyll, vascular bundle, root cortex and transpiration rate. Protein (P), total soluble sugars (AST), reducing sugars (AR) and starch content decreased in leaves and AST and starch content decrease in roots. In paspalo, varations on density and size of the stomatal cells, reduction of the metaxylem diameter and root cortex, increasing of bulliform cells size, leaf concentration of amino acid, AST, AR, and starch were observed.

Trocas gasosas de mudas de videira, obtidas por dois porta-enxertos, submetidas à deficiência hídrica

Gas exchange of vine cuttings obtained from two graftings submitted to water deficiency Abstract†n†The present work aimed to evaluate the water deficiency effect and two graftings on the gas exchange of vine cuttings under greenhouse conditions. eNiAEgara Rosadai (Vitis labrusca) was used as scion, and 101-14 (V.†riparia†x V.†rupestris) and 1103†Paulsen (V.†rupestris†x V.†berlandieri) were used as rootstocks. Twelve days after watering suspension, the leaf water potential of the combination eNiAEgara Rosadai/101-14 showed lower (-2.80†MPa) in relation to eNiAEgara Rosadai/1103 Paulsen (-2.10†MPa) in the non-irrigated plants, while relative water content altered only among watering levels. With the progress of water stress, there was a marked reduction in the gas exchange of the cultivar eNiAEgara Rosadai, which presented values close to zero, due to stomatal closure, without differences among the rootstocks. Only after twelve days without water the rootstocks influenced water use efficiency and photochemical efficiency of photosystem†II, where the combination eNiAEgara Rosadai/101-14, pre- sented lowest values to 1103†Paulsen. However, during water removal, the rootstock did not influence gas exchange of the eNiAEgara Rosadai, showing the same behavior in water deficiency.

Plasticidade anatômica das folhas de Xylopia brasiliensis Sprengel (Annonaceae)

Leaf anatomy of Xylopia is still poorly explored. The species Xylopia brasiliensis Sprengel, commonly known as pindaiba occurs in primary forest and in modified vegetation in a wide range of environmental conditions. The present study describes some leaf anatomical characteristics of this species and quantitatively evaluates them in function of environmental, seasonal and plant height differences. This species has anatomical plasticity.

Anatomical characteristics and nutrient uptake and distribution associated with the Cd-phytoremediation capacity of Eucalyptus camaldulenses Dehnh

Cadmium (Cd) is a hazardous heavy metal whose concentrations have been increasing in Brazilian soils, largely due to mining activities. Eucalyptus species are widely planted in Brazil to produce raw materials, and the confirmation of their phytoreme diation potential would link their economic and environmental roles. We examined the Cd-tolerance of Eucaliptus camaldulenses Dehnh and the anatomical and physiological features associated with that capacity. Plants were grown under greenhouse conditions in nutrient solutions with increasing concentrations of Cd (0, 15, 25, 45, 90 μmol m -3 ). Shoot biomass production was less sensitive to the phytotoxic effects of cadmium than root biomass production due to low Cd transport rates from roots to shoots. Increases in epidermal and endodermal thickness, changes in the vascular conductive elements of the roots, as well as differential nutrient distributions between roots and shoots are features of Cd tolerance in this species. The Cd tolerance of E. camaldulenses and its high biomass production support its potential use in Cd phytoremediation programs.

Aspectos anatômicos e fisiológicos de plantas de guaco submetidas a diferentes fotoperíodos

Guaco (Mikania glomerata Sprengel) is a medicinal species known because of its bronchi-dilating activity. Many studies have indicated changes in anatomical and physiological characteristics of medicinal plants when submitted to different conditions of light. The effect of photoperiods (8; 12; 16 and 20 h) on leaf anatomy, content of chlorophyll and stomatal conductance in distinct regions of guaco plants were analyzed. Adult plants of different sizes influenced by distinct photoperiods were submitted to anatomical and physiological analyses. 90 days after starting photoperiod treatments the chlorophyll content was higher in plants submitted to photoperiods of 8 and 12 hours in the superior and intermediary regions of plant, decreasing at 8 h of photoperiod treatment in the basal region of the plants. The conductance and stomatal density presented inverse relation to increase of photoperiod, decreasing from apical to basal regions of the plants. The thickness of the superior epidermis increased in the intermediary and basal regions of the plants submitted to a photoperiod up to 16 h. These regions presented a progressive increase of the lacunose parenchyma thickness under a photoperiod up to 20 h. The size and organization of the vascular bundles were influenced by the photoperiods.

Effects of different water regimes on the anatomical characteristics of roots of grasses promising for revegetation of areas surrounding hydroelectric reservoir

Conduziu-se o presente trabalho objetivavando-se avaliar o efeito de diferentes regimes hidricos sobre alguns aspectos da anatomia da raiz das seguintes gramineas: Echinochloa pyramidalis (canarana), Setaria anceps (setaria) e Paspalum paniculatum (paspalo). As plantas foram cultivadas em casa-de-vegetacao e submetidas a tres regimes hidricos: regas diarias; suspensao da rega e suspensao da rega seguida de submersao do sistema radicular. Foram retirados segmentos da parte mediana das raizes, os quais foram submetidos a tecnicas classicas em botânica para confeccao de lâminas e analise de tecidos. Foram observadas diferencas anatomicas nas tres especies de gramineas submetidas aos tres regimes hidricos com relacao ao numero de camadas de celulas do cortex externo e o espessamento de lignina e/ou suberina. As raizes em submersao nas tres especies apresentaram uma tendencia de aumento na proporcao da area do cortex destinada a aerenquimas, alem de um espessamento tanto da endoderme como das celulas do parenquima medular. Pela presenca de aerenquimas nas tres especies sujeitas aos tres regimes hidricos, infere-se que esses sao constitutivos. As adaptacoes desenvolvidas por essas especies contribuiram na compreensao da ocorrencia dessas em areas que passam por periodos de seca e inundacoes sucessivas.

Cd-tolerance markers of Pfaffia glomerata (Spreng.) Pedersen plants: anatomical and physiological features

Physiological and anatomical features of Cd-tolerance in Pfaffia glomerata were examined by exposing plantlets to nutrient solutions with increasing Cd concentrations (0, 15, 45, and 90 µmol Cd L-1), and possible Cd-tolerance markers were established. Cd contents were found to be higher in roots than in shoots. According to the bio-concentration factor data, this species is effectively a Cd-hyperaccumulator, as previously attested. Cd induced the appearance of xeromorphic characteristics in leaves (decreased water potential, increased numbers and decreased stomata size) and increased root endodermis thickness. The enzymatic antioxidant systems of roots and leaves were differently affected by Cd. The coordinated activities of antioxidant enzymes were effective in reducing Cd-induced reactive oxygen species in plants, mainly in leaves. Root endodermis thickness, stomatal size and numbers, root superoxide dismutase, and guaiacol peroxidase, as well as leaf guaiacol peroxidase and catalase activities can all be considered Cd-tolerance markers in Pfaffia glomerata. Due to its high root Cd accumulation, Pfaffia glomerata may be useful in Cd-phytoextraction programs, however the pharmacological use of plants grown in the presence of Cd must be avoided.

Características fisiológicas de microtomateiros fitocromo-mutantes

Objetivou-se, neste trabalho, caracterizar aspectos fisiologicos de microtomateiros (Lycopersicon esculentum P. Miller cv. Micro-Tom) fitocromo-mutantes. A cultivar Micro-Tom e os mutantes aurea (deficiente na biossintese do cromoforo dos fitocromos), atroviolacea (atv) e high pigment1 (hp1;ambos superexpressam eventos mediados por fitocromos) foram cultivados em condicoes controladas de luz e temperatura e caracterizados no estagio de floracao. O mutante hp1 obteve as maiores taxas de fotossintese potencial e de conteudo de carotenoides. O mutante aurea manteve taxas de fotossintese potencial similares a cultivar Micro-Tom, mesmo expressando o mais baixo conteudo de clorofilas, e tambem expressou o maior conteudo de nitrogenio entre os demais microtomateiros. Os mutantes aurea e hp1 obtiveram os menores conteudos de acucares soluveis totais. O mutante atv expressou o maior conteudo de clorofilas e tambem a menor razao clorofila a/b.

Alterações bioquímicas de plantas e morfológicas de gemas de cafeeiro associadas a eventos do florescimento em resposta a elementos meteorológicos

Flowering on coffee plants involves several aspects from the plant as well as from the environment. Understanding these interactions can enhance the knowledge and promote better handling of the crop in field, mainly related to irrigation to promote synchronized flowering and consequently the uniform fruit maturation, lowering the production costs. The aim of the present study was to evaluate bud morphology, proline and abscisic acic biosynthesis on coffee plants under different environmental conditions in order to contribute to the knowledge in factors that influence flowering synchronization. Scanning electron microscopic was performed on buds of plagiotropic shoots weekly collected from November/04 to February/05. Predawn water potential and proline content analysis were carried out from July to September/05 using complete superior third expanded leaves from plagiotropic shoots of non and irrigated plants. Abcisic acid content was also evaluated in xylem sap and on flower buds. The results show alterations on bud morphology associated to the period of water deficit followed by precipitation and also, consequently, lower thermic amplitude. Regarding to the water potential, differences could be observed in the treatments having -0.3 and 0.8MPa for irrigated and -0.6 and -1.5MPa for non-irrigated plants. The highest proline and abcisic acid content are related to dryer period, however there is no direct relationship between these biosynthesis compounds and the different flowering stages evaluated.