Reserve carbohydrates and lipids from the seeds of four tropical tree species with different sensitivity to desiccation

Considering the importance of water content for the conservation and storage of seeds, and the involvement of soluble carbohydrates and lipids for embryo development, a comparative study was carried out among the seeds of Inga vera (ingá), Eugenia uniflora (pitanga), both classified as recalcitrant, and Caesalpinia echinata (brazilwood) and Erythrina speciosa (mulungu), considered as orthodox seeds. Low concentrations of cyclitols (0.3-0.5%), raffinose family oligosaccharides (ca. 0.05%) and unsaturated fatty acids (0-19%) were found in the seeds of ingá and pitanga, while larger amounts of cyclitols (2-3%) and raffinose (4.6-13%) were found in brazilwood and mulungu, respectively. These results, in addition to higher proportions of unsaturated fatty acids (53-71%) in orthodox seeds, suggested that sugars and lipids played important role in water movement, protecting the embryo cell membranes against injuries during dehydration.

Tropical woods: influence of density in hardness parallel and normal to the grain for some Brazilian tropical tree species

The aim of this work is to verify the possibility to correlating specific gravity and wood hardness parallel and perpendicular to the grain. The purpose is to offer one more tool to help in the decision about wood species choice for use in floors and sleepers. To reach this intent, we considered the results of standard tests (NBR 7190:1997, Timber Structures Design, Annex B, Brazilian Association of Technical Standards) to determine hardness parallel and normal to the grain in fourteen tropical high density wood species (over 850 kg/m(3), at 12% moisture content). For each species twelve determinations were made, based on the material obtained at Sao Carlos and its regional wood market. Statistical analysis led to some expressions to describe the cited properties relationships, with a determination coefficient about 0.8.

Differential responses of antioxidant enzymes in pioneer and late-successional tropical tree species grown under sun and shade conditions

To investigate the ability of pioneer and late-successional species to adapt to a strong light environment in a reforestation area, we examined the activities of antioxidant enzymes in relation to photosystem chlorophyll a fluorescence and photosynthetic pigment concentration for eight tropical tree species grown under 100% (sun) and 10% (shade) sunlight irradiation. The pioneer (early-succession) species (PS) were Cecropia pachystachya, Croton urucurana, Croton floribundus and Schinus terebinthifolius. The non-pioneer (late succession) species (LS) were Hymenaea courbaril L var. stilbocarpa, Esenbeckia leiocarpa, Cariniana legalis and Tabebuia roseo-alba. We observed a greater decline in the ratio of variable to maximum chlorophyll a fluorescence (F(v)/F(m)) under full sunlight irradiation in the late-successional species than in the pioneer species. The LS species most sensitive to high irradiance were C. legalis and H. courbaril. In LS species, chlorophyll a, chlorophyll b and total chlorophyll concentrations were higher in the shade-grown plants than in plants that developed under full sunlight, but in the PS species C. floribundus and C. pachystachya, we did not observe significant changes in chlorophyll content when grown in the two contrasting environments. The carotenoids/total chlorophyll ratio increased significantly when plants developed under high-sunlight irradiation, but this response was not observed in the PS species S. terebinthifolius and C. pachystachya. The improved performance of the pioneer species in high sunlight was accompanied by an increase in superoxide dismutase (SOD. EC 1.15.1.1) activity, though no light-dependent increase in the activity of ascorbate peroxidase (APX. EC 1.11.1.11) was observed. The activity of catalase (CAT, EC 1.11.1.6) was reduced by high irradiation in both pioneer and late-successional species. Our results show that pioneer species perform better under high-sunlight irradiation than late-successional species, as indicated by increased SOD activity and a higher F IF,, ratio. C. legalis was the LS species most susceptible to photoinhibition under full sunlight conditions. These results suggest that pioneer plants have more potential tolerance to photo-oxidative damage than late-successional species associated with the higher SOD activity found in pioneer species. Reduced photoinhibition in pioneer species probably results from their higher photosynthetic capacities, as has been observed in a previous survey carried out by our group. (C) 2010 Elsevier B.V. All rights reserved.

Microsatellite diversity and effective population size in a germplasm bank of Hymenaea courbaril var. stilbocarpa (Leguminosae), an endangered tropical tree: recommendations for conservation

Deforestation in southeast Brazil has led to the extinction of Hymenaea courbaril var. stilbocarpa and ex situ conservation has been established. In this study, the levels of genetic diversity and the effective population size of H. courbaril in a germplasm bank were investigated using six nuclear microsatellite loci. A total of 79 and 91 alleles were found in 65 seed-trees and their 176 offspring, respectively. Offspring have a higher average number of alleles per locus (A = 15.2) than seed-trees (A = 13.2), but lower observed heterozygosity (offspring: H (o) = 0.566; seed-trees: H (o) = 0.607). The estimate of outcrossing rate shows that the study population is perfectly outcrossed (t (m) = 0.978, P > 0.05). Significant deviations from random mating were detected through mating among relatives and correlated matings. The average variance in effective population size for each family was 2.63, with a total effective population size retained in the bank of 170.1. These results confirm that the preserved population of H. courbaril retains substantial genetic variability.

Development and characterization of 15 microsatellite loci for Cariniana estrellensis and transferability to Cariniana legalis, two endangered tropical tree species

From a genomic library enriched for GA/CA repeats, 15 highly polymorphic microsatellite markers were developed for Cariniana estrellensis, a tropical forest tree. The microsatellite loci were screened in 49 mature trees found between Pardo river and Mogi-Gua double dagger u river basins, in the state of So Paulo, Brazil. A total of 140 alleles were detected with an average of 9.33 alleles per locus. The expected heterozygosity ranged from 0.37 to 0.88. These loci showed a high probability of paternity exclusion. Additionally, 12 loci were effectively transferred to Cariniana legalis. High levels of polymorphism make the present SSR markers useful for population genetic studies.

Transferability and characterization of nine microsatellite markers for the tropical tree species Tabebuia roseo-alba

Microsatellite loci that were previously developed in the tropical tree Tabebuia aurea were used for the genetic analysis of Tabebuia roseo-alba populations. Nine of 10 simple sequence repeat markers were amplified, and the polymorphism was assessed in 58 individuals sampled from two stands in southeastern Brazil. All loci were polymorphic with Mendelian inheritance. The allele numbers were high, ranging from 5 to 13 in population I and 3 to 7 in population II, with means of 8.9 and 5.5, respectively. We conclude that these markers can be efficiently used for parentage and gene-flow studies.

Effects of abscisic acid, ethylene and sugars on the mobilization of storage proteins and carbohydrates in seeds of the tropical tree Sesbania virgata (Leguminosae)

Endospermic legumes are abundant in tropical forests and their establishment is closely related to the mobilization of cell-wall storage polysaccharides. Endosperm cells also store large numbers of protein bodies that play an important role as a nitrogen reserve in this seed. In this work, a systems approach was adopted to evaluate some of the changes in carbohydrates and hormones during the development of seedlings of the rain forest tree Sesbania virgata during the period of establishment. Seeds imbibed abscisic acid (ABA), glucose and sucrose in an atmosphere of ethylene, and the effects of these compounds on the protein contents, alpha-galactosidase activity and endogenous production of ABA and ethylene by the seeds were observed. The presence of exogenous ABA retarded the degradation of storage protein in the endosperm and decreased alpha-galactosidase activity in the same tissue during galactomannan degradation, suggesting that ABA represses enzyme action. On the other hand, exogenous ethylene increased alpha-galactosidase activity in both the endosperm and testa during galactomannan degradation, suggesting an inducing effect of this hormone on the hydrolytic enzymes. Furthermore, the detection of endogenous ABA and ethylene production during the period of storage mobilization and the changes observed in the production of these endogenous hormones in the presence of glucose and sucrose, suggested a correlation between the signalling pathway of these hormones and the sugars. These findings suggest that ABA, ethylene and sugars play a role in the control of the hydrolytic enzyme activities in seeds of S. virgata, controlling the process of storage degradation. This is thought to ensure a balanced flow of the carbon and nitrogen for seedling development.

Characterization of unisexual flower development in the endangered mahogany tree Swietenia macrophylla King. (Meliaceae)

The selection of candidate plus trees of desirable phenotypes from tropical forest trees and the rapid devastation of the natural environments in which these trees are found have created the need for a more detailed knowledge of the floral and reproductive biology of tropical tree species. In this article, the organogenic processes related to unisexual flower development in tropical mahogany, Swietenia macrophylla, are described. Mahogany inflorescences at different developmental stages were evaluated using scanning electron microscopy or optical microscopy of histological sections. The unisexual flowers of S. macrophylla are usually formed in a thyrse, in which the positions of the female and male flowers are not random. Differences between male and female flowers arise late during development. Both female and male flowers can only be structurally distinguished after stage 9, where ovule primordia development is arrested in male flowers and microspore development is aborted in female flower anthers. After this stage, male and female flowers can be distinguished by the naked eye as a result of differences in the dimensions of the gynoecium. The floral characteristics of S. macrophylla (distribution of male and female flowers within the inflorescence, and the relative number of male to female flowers) have practical implications for conservation strategies of this endangered species. (c) 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156, 529-535.

Tree-ring formation, radial increment periodicity, and phenology of tree species from a seasonal semi-deciduous forest in southeast Brazil

Many tropical tree species produce growth rings in response to seasonal environmental factors that influence the activity of the vascular cambium. We applied the following methods to analyze the annual nature of treering formation of 24 tree species from a seasonal semi-deciduous forest of southeast Brazil: describing wood anatomy and phenology, counting tree rings after cambium markings, and using permanent dendrometer bands. After 7 years of systematic observations and measurements, we found the following: the trees lost their leaves during the dry season and grew new leaves at the end of the same season; trunk increment dynamics corresponded to seasonal changes in precipitation, with higher increment (active period) during the rainy season (October-April) and lower increment (dormant period) during the dry season (May-September); the number of tree rings formed after injuries to the cambium coincided with the number of years since the extraction of the wood samples. As a result of these observations, it was concluded that most study trees formed one growth ring per year. This suggests that tree species from the seasonal semi-deciduous forests of Brazil have an annual cycle of wood formation. Therefore, these trees have potential for use in future studies of tree age and radial growth rates, as well as to infer ecological and regional climatic conditions. These future studies can provide important information for the management and conservation of these endangered forests.

Cell wall polysaccharides from cell suspension cultures of the Atlantic Forest tree Rudgea jasminoides (Rubiaceae)

Rudgea jasminoides (Rubiaceae) is a tropical tree species native of the Atlantic Forest in the south of Brazil. Previous studies with leaf cell walls of R. jasminoides showed a different proportion of cross-linked glycans compared to what is usually reported for eudicots. However, due to the difficulties of working with whole plant organs, cell suspensions of R. jasminoides, consisting of predominantly undifferentiated cells with mainly primary cell walls, were used to examine cell walls and extracellular soluble polysaccharides (EP) released into the culture medium. Sugar composition and linkage analysis showed homogalacturonans, xylogalacturonans and arabinogalactans to be the predominant EP. In the cell wall, homogalacturonans and arabinogalactans are the major pectins, and xyloglucans and xylans are the major cross-linking glycans. The presence of xylogalacturonans in the R. jasminoides cell cultures seems to be related to the occurrence of a homogeneous cell suspension with loosely attached cells. Although all alkali extractions from the cell walls yielded amounts of xyloglucan that exceed those of the xylans, the latter was found in a proportion that is higher than what has been usually reported for primary cell walls of most eudicots. The xyloglucan from cell walls of cell suspension cultures of R. jasminoides has low fucosylation levels and high proportion of galactosyl residues, a branching pattern commonly found in storage cell-wall xyloglucans.

Spatial genetic structure of Hymenaea stigonocarpa Mart. ex Hayne assessed with chloroplast microsatellite markers

The use of chloroplast DNA markers (cpDNA) helps to elucidate questions related to ecology, evolution and genetic structure. The knowledge of inter-and intra-population genetic structure allows to design effective conservation and management strategies for tropical tree species. With the aim to help the conservation of Hymenaea stigonocarpa of the Cerrado (Brazilian savanna) in Sao Paulo State, an analysis of the spatial genetic structure (SGS) was conducted in two populations using five universal chloroplast microsatellite loci (cpSSR). The population of 68 trees of H. stigonocarpa in the Ecological Station of Itirapina (ESI) had a single haplotype, indicating a strong founder effect. In turn, the population of 47 trees of H. stigonocarpa in a contiguous area that includes the Ecological Station of Assis and the Assis State Forest (ESA), showed six haplotypes ((n) over cap (h) = 6) with a moderate haplotype diversity ((h) over cap = 0667 + 0094), revealing that it was founded by a small number of maternal lineages. The SGS analysis for the population ESA/ASF, using Moran`s I index, indicated limited seed dispersal. Considering SGS, for ex situ conservation strategies in the population ESA/ASF, seed harvesting should require a minimum distance of 750 m among seed-trees.

Mendelian inheritance, linkage and linkage disequilibrium in microsatellite loci of Copaifera langsdorffii Desf.

Copaifera langsdorffii is a Neotropical tree with wide distribution in the Brazilian Atlantic rain forest and savanna. Although eight microsatellite loci (SSR) were developed in 2000 and have been widely used since then, there is yet no information about their inheritance, linkage and linkage disequilibrium (LD). Through the analysis of 28 open-pollinated (OP) progenies, the SSR loci revealed Mendelian inheritance and independent assortment. Using these progenies, young and adult trees LD was mainly detected in OP progenies. Our results show clear evidence that the eight SSR loci can be used without restriction in genetic diversity, mating system and parentage analysis.

Understanding the genetic diversity, spatial genetic structure and mating system at the hierarchical levels of fruits and individuals of a continuous Theobroma cacao population from the Brazilian Amazon

Understanding the mating patterns of populations of tree species is a key component of ex situ genetic conservation. In this study, we analysed the genetic diversity, spatial genetic structure (SGS) and mating system at the hierarchical levels of fruits and individuals as well as pollen dispersal patterns in a continuous population of Theobroma cacao in Para State, Brazil. A total of 156 individuals in a 0.56 ha plot were mapped and genotyped for nine microsatellite loci. For the mating system analyses, 50 seeds were collected from nine seed trees by sampling five fruits per tree (10 seeds per fruit). Among the 156 individuals, 127 had unique multilocus genotypes, and the remaining were clones. The population was spatially aggregated; it demonstrated a significant SGS up to 15m that could be attributed primarily to the presence of clones. However, the short seed dispersal distance also contributed to this pattern. Population matings occurred mainly via outcrossing, but selfing was observed in some seed trees, which indicated the presence of individual variation for self-incompatibility. The matings were also correlated, especially within ((r) over cap (p(m)) = 0.607) rather than among the fruits ((r) over cap (p(m)) = 0.099), which suggested that a small number of pollen donors fertilised each fruit. The paternity analysis suggested a high proportion of pollen migration (61.3%), although within the plot, most of the pollen dispersal encompassed short distances (28m). The determination of these novel parameters provides the fundamental information required to establish long-term ex situ conservation strategies for this important tropical species. Heredity (2011) 106, 973-985; doi:10.1038/hdy.2010.145; published online 8 December 2010

Genetic analysis of forest species Eugenia uniflora L. through of newly developed SSR markers

Nine microsatellite loci for genetic analysis of three populations of the tropical tree Eugenia uniflora L. (pitanga or Brazilian cherry) from fragments of semideciduous forest were developed. We used the technique of building a (GA)(n) and (CA)(n) microsatellite-enriched library by capture with streptavidin-coated magnetic beads. We assessed the polymorphism of seven microsatellites in 84 mature trees found in three areas (Ribeir (a) over tildeo Preto, Tambau and S (a) over tildeo Jose do Rio Pardo), highly impacted by the agricultural practices, in a large region among Pardo river and Mogi-Guacu river basins, in state of S (a) over tildeo Paulo, Brazil. All loci were polymorphic, and the number of alleles was high, ranging from 6 to 24, with a mean of 14.4. All stands showed the same high level of genetic diversity (mean H(E) = 0.83) and a low genetic differentiation (mean F(ST) = 0.031), indicating that genetic diversity was higher within rather than among populations. Seven of the nine loci were highly variable, and sufficiently informative for E. uniflora. It was concluded that these new SSR markers can be efficiently used for gene flow studies.

Tibouchina pulchra (Cham.) Cogn., a native Atlantic Forest species, as a bio-indicator of ozone: Visible injury

Tibouchina pulchra saplings were exposed to carbon filtered air (CF), ambient non-filtered air (NF) and ambient non-filtered air + 40 ppb ozone (NF + O-3) 8 h per day during two months. The AOT40 values at the end of the experiment were 48, 910 and 12,895 ppb h(-1), respectively, for the three treatments. After 25 days of exposure (AOT40=3871 ppb h(-1)), interveinal red stippling appeared in plants in the NF + O-3 chamber. In the NF chamber, symptoms were observed only after 60 days of exposure (AOT40 = 910 ppb h(-1)). After 60 days, injured leaves per plant corresponded to 19% in NF + O-3 and 1% in the NF treatment; and the average leaf area injured was 7% within the NF + O-3 and 0.2% within the NF treatment. The extent of leaf area injured (leaf injury index) was mostly explained by the accumulated exposure of ozone (r(2) = 0.89; p < 0.05). (C) 2007 Elsevier Ltd. All rights reserved.