Aristéa Alves Azevedo

Flúor em chuva simulada: sintomatologia e efeitos sobre a estrutura foliar e o crescimento de plantas arbóreas

Fluoride in simulated rain: symptomatology and effects on leaf structure and growth of wood plants). The objectives of this study was to characterize the effects of fluoride on seedlings and young plants of native woody species from Parque Estadual do Rio Doce (MG) and on the leaf blade structure of the most sensitive of the studied tree species. This work was carried out to gain information on diagnosing criteria for bioindication and to throw some light on the mechanisms of plant resistance and tolerance in order to assist in the revegetation programs of highly affected areas. The employed species were Gallesia gorazema Moq. (Phytolac- caceae), Genipa americana L. (Rubiaceae), Joannesia princeps Vell. (Euphorbiaceae), Peltophorum dubium (Spreng.) Taub. (Legu- minosae, Caesalpinioideae) and Spondias dulcis Forst. f. (Anarcadiaceae). Seedlings and young plants of those species were submitted to rain with dissolved fluoride (30 mg.L -1 ), during 20 min daily, for 10 consecutive days. Apical and marginal necrosis occurred in the leaf blades of all species just after the first simulated rain. Two days after treatment, S. dulcis, in the young plant stage, showed to be the most sensitive species by exhibiting large necrotic areas, while G. americana was the most resistant species. At the young plant stage, the species that accumulated more fluoride were also the most sensitive ones; such a relation was not observed in plants at the seedling stage. The pollutant at the level employed caused drastic alterations in the leaf blade of S. dulcis and also damaged all of its anatomical structure. The high susceptibility of S. dulcis to fluoride suggests that this species possess potential features to be employed as a bioindicator. However, for a better characterization of the responses of S. dulcis to fluoride and its usage in biomonitoring programs, more studies are required. RESUMO - (Fluor em chuva simulada: sintomatologia e efeitos sobre a estrutura foliar e o crescimento de plantas arboreas). Os objetivos deste trabalho foram: caracterizar os efeitos do fluor em especies arboreas nativas, nos estadios de plântula e muda; identificar injurias provocadas pelo fluor na estrutura da lâmina foliar da especie mais sensivel; fornecer subsidios para selecao de caracteristicas a serem utilizadas na bioindicacao; e contribuir com informacoes sobre a resistencia ou tolerância das plantas, visando ao reflorestamento de areas impactadas pela chuva com fluor. As especies analisadas foram Gallesia gorazema Moq. (Phytolaccaceae), Genipa americana L. (Rubiaceae), Joannesia princeps Vell. (Euphorbiaceae), Peltophorum dubium (Spreng.) Taub. (Leguminosae, Caesalpinioideae) e Spondias dulcis Forst. f. (Anacardiaceae). Plântulas e mudas dessas especies, provenientes do Parque Estadual do Rio Doce (MG), foram submetidas a 20 min diarios de chuva com fluor (30 mg.L -1 ), por 10 dias consecutivos. Necroses apicais e marginais foram observadas em todas as especies analisadas, logo apos a primeira chuva simulada. S. dulcis, no estadio de muda, foi a especie mais sensivel ao fluor, pois apresentou extensas necroses com apenas dois dias de tratamento, enquanto que G. americana foi a especie mais resistente. Nas mudas, as especies que acumularam mais fluor foram tambem as que apresentaram maior sensibilidade a esse poluente; essa relacao nao foi verificada nas plântulas. A concentracao de fluor utilizada promoveu alteracoes drasticas na lâmina foliar de S. dulcis com extensas areas necrosadas, danificando toda a sua estrutura anatomica. A sensibilidade ao fluor observada em S. dulcis indica que essa especie apresenta potencial para ser usada como bioindicadora. Entretanto, estudos detalhados serao necessarios para a melhor caracterizacao das respostas de S. dulcis ao fluor visando a sua utilizacao em programas de biomonitoramento ambiental.

Effects of simulated acid rain on leaf anatomy and micromorphology of Genipa americana L. (Rubiaceae)

Experimentos foram conduzidos para avaliar o grau de susceptibilidade e determinar as injurias causadas pela chuva acida simulada na anatomia e micromorfologia foliar de Genipa americana. Plantas foram expostas a chuva com pH 3,0 durante 10 dias consecutivos. No tratamento controle utilizou-se apenas agua destilada (pH 6,0). Amostras foliares foram coletadas e fixadas para microscopia de luz e eletronica de varredura. Foram observados nas folhas expostas a chuva acida: necroses pontuais intervenais, colapso das celulas do mesofilo e da epiderme; hipertrofia do parenquima lacunoso e acumulo de compostos fenolicos e graos de amido. A analise micromorfologica evidenciou, nas areas necrosadas, plasmolise das celulas-guarda e ruptura da cuticula e da crista estomatica. Alteracoes anatomicas ocorreram antes que sintomas visuais fossem observados nas folhas. Estes resultados comprovam a importância de dados anatomicos na diagnose precoce da injuria e na determinacao da sensibilidade de G. americana a chuva acida.

Leaf anatomy as an additional taxonomy tool for 16 species of Malpighiaceae found in the Cerrado area (Brazil).

This work describes the leaf anatomy of 16 species belonging to three genera of the Malpighiaceae family found in the Cerrado (Minas Gerais State, Brazil). The scope of this study was to support the generic delimitation by contributing to the identification of the species and constructing a dichotomous identification key that includes anatomical characters. The taxonomic characters that were considered to be the most important and used in the identification key for the studied Malpighiaceae species were as follows: the presence and location of glands; presence of phloem in the medullary region of the midrib; mesophyll type; presence and type of trichomes; and presence, quantity, and disposition of accessory bundles in the petiole. It was also possible to indicate promising characters for future taxonomic and phylogenetic studies in the Malpighiaceae family, especially for the Banisteriopsis, Byrsonima, and Heteropterys genera.

Articulated laticifers in the vegetative organs of Mandevilla atroviolacea (Apocynaceae, Apocynoideae)

The occurrence of nonarticulated laticifers has been recorded in the literature for Apocynaceae, but little infor- mation is available on their structure and the chemical compounds in their latex. The objective of this study was to de- scribe, anatomically and histochemically, the laticifers and latex found in the roots, stems, and leaves of Mandevilla atroviolacea (Stadelm) Woodson, a genus in the Apocynaceae. Laticifer anatomy was examined by light microscopy, and the chemical nature of the exuded latex was studied using cytochemistry. Articulated laticifers were present in M. atroviolacea. The lactiferous system in stems and leaves originated from both procambium and ground meristem, and it was determined to be functional, as indicated by changes in the cytoplasm immediately subsequent to its formation. However, in tuberous roots, laticifers originated from the vascular cambium, phellogen, and parenchymatous cortical cells. The primary wall of laticifers consists of pectins and cellulose and is thicker than that of adjacent cells. The laticifer secre- tion contained an emulsion of lipophilic substances rich in neutral lipids, resin oils, and possibly rubber. The presence of articulated laticifers is reported for the first time for Apocynoideae, contributing to the knowledge and understanding of these structures in the family Apocynaceae.

Ação do flúor dissolvido em chuva simulada sobre a estrutura foliar de Panicum maximum Jacq. (Colonião) e Chloris gayana Kunth. (Capim-Rhodes): Poaceae

Panicum maximum e Chloris gayana foram submetidas a chuvas simuladas com solucoes de fluoreto de potassio (15mg ml-1) com objetivo de identificar as injurias causadas pelo fluor (F-), como poluente atmosferico, na estrutura da lâmina foliar e fornecer subsidios para a selecao de caracteristicas diagnosticas a serem utilizadas na bioindicacao. Os principais sintomas foram clorose e necrose, principalmente no apice e margens das lâminas. Nos cortes transversais, quatro tipos de alteracoes causadas pelo fluor sao relacionadas: reducao do numero, tamanho e arranjo dos cloroplastos; necrose dos tecidos principalmente nas margens das folhas; erosoes na superficie da folha e hipertrofia das celulas. Em C. gayana, no entanto, nao foram observadas as alteracoes nos cloroplastos e os outros sintomas foram bem mais discretos que em P. maximum. A ocorrencia de compostos fenolicos foi registrada pela coloracao com fucsina em todas as regioes da lâmina onde foram observadas lesoes. Ao microscopio eletronico de varredura foi observado o achatamento e formacao de concavidades nas paredes externas das celulas. Este experimento confirma a maior sensibilidade de P. maximum ao fluor e revela algumas caracteristicas anatomicas de C. gayana que, entre outros fatores, podem estar contribuindo para a maior resistencia desta especie a este poluente.

Iron plaque formation and morphoanatomy of roots from species of restinga subjected to excess iron

The restingas, a sandy coastal plain ecosystem of Brazil, have received an additional amount of iron due to the activity of mining industries. The present study aims to characterize morphoanatomically and histochemically the iron plaque formation on roots of Ipomoea pes-caprae L. and Canavalia rosea DC, cultivated in hydroponic solution with and without excess iron. The iron plaque formation as well as changes in the external morphology of the lateral roots of both species were observed after the subjection to excess iron. Changes in the nutrient uptake, and in the organization and form of the pericycle and cortex cells were observed for both species. Scanning electron microscopy showed evident iron plaques on the whole surface of the root. The iron was histolocalized in all root tissues of both species. The species of restinga studied here formed iron plaque in their roots when exposed to excess of this element, which may compromise their development in environments polluted by particulated iron.

Anatomical and histochemical characterization of extrafloral nectaries of Prockia crucis (Salicaceae)

Besides being vital tools in taxonomic evaluation, the anatomy of plant secretory structures and the chemical composition of their secretions may contribute to a more thorough understanding of the roles and functions of these secretory structures. Here we used standard techniques for plant anatomy and histochemistry to examine secretory structures on leaves at different stages of development of Prockia crucis, to evaluate the origin and development of the structures, and to identify the disaccharides and monosaccharides in the exudates. Fructose, glucose, and sucrose constituted up to 49.6% of the entire secretion. The glands were confirmed to be extrafloral nectaries (EFNs); this is the first report of their presence in the genus Prockia. These EFNs are globular, sessile glands, with a central concavity occurring on the basal and marginal regions of the leaf. The epidermis surrounding the concavity is secretory, forming a single-layered palisade that strongly reacts with periodic acid-Schiffs reagent (PAS) and xylidine Ponceau, indicators of total polysaccharides and total proteins, respectively, in the exudate. On the basis of the similarity of these glands to the salicoid teeth in Populus and Salix, we suggest that these three taxa are phylogenetically close.

Diagnostic and prognostic characteristics of phytotoxicity caused by fluoride on Spondias dulcis Forst. F. (Anacardiaceae)

The goal of this study was to determine the symptoms and microscopic damage caused by fluoride on Spondias dulcis, a fluoride-sensitive species. The plants were exposed to simulated fog with fluoride (0, 5, 10, 15 and 20 mg L(-1)) for 20 min daily during four consecutive days. Samples from leaflets without any apparent fluoride injury were collected to microscopic analysis. The percentage of necrosed leaf area was measured, and the level of pollutant in the dry matter from the basal and apical portions of the plant was determined. The necroses began 24 h after the first simulation mainly from the base of the leaflets. A higher level of necrosis was observed at the apical portion of the plants, a region of higher fluoride accumulation. The damage on the surface of the leaflets was characterized as plasmolysis, erosion of the epicuticular waxes and epidermal rupture. Structurally, the noticeable accumulation of granules and droplets green stained by toluidine blue in the spongy parenchima and the boundaries of ending veinlets was observed. The limb thickness reduction occurred due to plasmolysis in the mesophyll, showing an apparent correlation with the damage observed on the surface. The parameters observed in the laboratory are promising for field biomonitoring studies.

EFEITO DE TRICOMAS, ALELOQUÍMICOS E NUTRIENTES NA RESISTÊNCIA DE LYCOPERSICON HIRSUTUM À TRAÇA-DO-TOMATEIRO

The objective of this work was to study the effect of trichomes, alellochemicals and minerals in the leaves of different canopy heights on the resistance of Lycopersicon hirsutum to tomato leaf miner, Tuta absoluta (Lepidoptera: Gelechiidae). Effects of 2-tridecanone (2-TD), 2-undecanone (2-UD), N, P, K, Ca and Mg levels, density and types of trichomes and leaf area on apical, medium and basal parts of plant dossel of L. hirsutum and L. esculentum on the oviposition and mines number of T. absoluta was studied. Production of 2-TD increased from the bottom to the top of the canopy. The apical part of plants of L. hirsutum showed more antibiotic effect on the caterpillar. T. absoluta oviposited more on leaves of the apical and medium portion of the plants than in the basal parts of L. esculentum.

Anatomia foliar como subsídio à taxonomia de Hippocrateoideae (Celastraceae) no Sudeste do Brasil

Leaf anatomy of thirteen species belonging to nine genera of the subfamily Hippocrateoideae (Celastraceae) was studied, in order to select anatomical characters to help the taxonomy at genera and species levels. The species studied were: Anthodon decussatum Ruiz & Pav., Cheiloclinium cognatum (Miers) A.C. Sm., Cheiloclinium serratum (Cambess.) A.C. Sm., Cuervea crenulata Mennega, Elachyptera micrantha (Cambess.) A.C. Sm., Hippocratea volubilis L., Peritassa flaviflora A.C. Sm., Peritassa mexiae A.C. Sm., Pristimera nervosa (Miers) A.C. Sm., Salacia crassifolia (Mart. ex Schult.) G. Don, Tontelea fluminensis (Peyr.) A.C. Sm., Tontelea leptophylla A.C. Sm. and Tontelea miersii (Peyr.) A.C. Sm. The selected anatomical characters that can be used as diagnostic for the taxonomy of the distinct genera and species are: the type of sclereids in petiole or leaf blade, stomata type, the conformation of the petiole vascular system, shape of epidermal cell walls, presence of hypodermis, occurrence of laticifers, among others.