Evaluation of the viability and germination of tempisque [<i>Sideroxylon capiri</i> (A.DC.) Pittier Sapotaceae]

The tempisque (Sideroxylon capiri) is a tree native to Mexico used by the rural population for housing construction, poles and hedges, as fuel (wood) and also for fodder and ornamental purposes, among others. It is considered an endangered species. In order to contribute to its preservation and sustainable management, it was considered important to determine the proportion of viable seeds, the loss of viability due to storage period and the germination process by applying pregerminative treatments. We found that freshly collected seeds showed 100% viability, which decreased to 0% after 5 months of storage. According to the cumulative germination significant differences between treatments (p≤0.01) were found. It was observed that seeds can accelerate their time of germination with the previous exposure of 24 h in water at room temperature. The soaking treatment in water for 24 h at room temperature obtained final germination of 55%, while with the control 39% was reached. Soaking in hydrogen peroxide and scarification were the treatments with lower germination percentage (33 and 23%, respectively). To get a higher percentage of germinated seeds in a short time, it is necessary to give a soaking treatment in water for 24 h before sowing.     

<Emphasis Type="Italic">Lecomtedoxa plumosa</Emphasis> (Sapotaceae), a new tree species from Korup National Park,Cameroon

Summary   Lecomtedoxa plumosa Burgt (Sapotaceae), a new tree species from the southern part of Korup National Park in Cameroon, is described and illustrated. The flowers show the characteristics of the genus Lecomtedoxa: for example the staminodes are free and placed alternately to the stamens and corolla lobes. The leaves of the new species are clearly different from other Lecomtedoxa spp., but they look similar to the leaves of Gluema ivorensis, especially to those of the collections from Cameroon. In total 26 trees ≥ 10 cm dbh were found. The largest trees found were 36 m high and 74 cm dbh. The trees grow in primary rain forest, in clusters of up to 10 trees on 2 ha, mixed with many other tree species. The seed dispersal is ballistic. The conservation status of the species is assessed as Endangered, EN D.     

Purification and partial biochemical characterization of polyphenol oxidase from mamey (Pouteria sapota)

While a long shelf life for fruit products is highly desired, enzymatic browning is the main cause of quality loss in fruits and is therefore a main problem for the food industry. In this study polyphenol oxidase (PPO), the main enzyme responsible for browning was isolated from mamey fruit (Pouteria sapota) and characterized biochemically. Two isoenzymes (PPO 1 and PPO 2) were obtained upon ammonium sulfate precipitation and hydrophobic and ion exchange chromatography; PPO 1 was purified up to 6.6-fold with 0.28% yield, while PPO 2 could not be characterized as enzyme activity was completely lost after 24 h of storage. PPO 1 molecular weight was estimated to be 16.1 and 18 kDa by gel filtration and SDS-PAGE, respectively, indicating that the native state of the PPO 1 is a monomer. The optimum pH for PPO 1 activity was 7. The PPO 1 was determined to be maximum thermally stable up to 35 °C. Kinetic constants for PPO 1 were K_m = 44 mM and K_m = 1.3 mM using catechol and pyrogallol as substrate, respectively. The best substrates for PPO 1 were pyrogallol, 4-methylcatechol and catechol, while ascorbic acid and sodium metabisulfite were the most effective inhibitors.     

Serology and systematics of the Ebenales and the Theales

The systematic position ofthe Ebenaceae, Sapotaceae, Styracaceae, Ochnaceae, Stachyuraceae, Dipterocarpaceae, Clusiaceae and Hypericaceae has been investigated using serological comparisons of sets of antigenic determinants. The results show that the Sytracaceae and Sapotaceae are undoubtedly more closely associated with the Actinidiaeceae and Theaceae, respectively, than with each other. We found no corresponding determinants betnween antigen systems from the Ebenaceae and systems from any other family whose relations to this family have been proposed. As discovered previously, investigations of antigen systems from the Ochnaceae, Dipterocarpaceae, Stachyuraceae, Clusiaceae and Hypericaceae are against the idea of a natural order “Theales” in which these families, or at least some of them, are combined with the Theaceae and Actinidiaceae. This paper completes our previous investigations which largely support a superorder Ericanae sensu Ehrendorfer and Takhtajan. We propose to include the Actinidiaceae and Theaceae in this superorder, assigning them a central position laong with the Sapotaceae and Sytracaeae on one side and the Primulales and Ericales on the other. Another most interesting finding is that there are corresponding determinants between antigen systems from the members of the Ericanae and representatives of the Polemoniaceae and Loasaceae.     

Pentacyclic triterpenoid and saponins from Gambeya boukokoensis

Chemical studies of the EtOAc extract of Gambeya boukokoensis Aubr. et Pellegr. stem bark led to the isolation of eight compounds. Three of them were elucidated as new compounds and designated as: gamboukokoensein A, 1alpha,2alpha,3beta,19alpha,23-pentahydroxyurs-12-en-28-oic acid; gamboukokoenside A, 2beta,3beta,6beta,28-tetrahydroxyolean-12-en-23-oic acid 23-O-alpha-L-arabinopyranosyl ester and gamboukokoenside B, 6beta,28-dihydroxy-3-oxoolean-12-en-23-oic acid 23-O-alpha-L-arabinopyranosyl ester. The other five compounds were known and identified as myrianthic acid, protobassic acid, oleanolic acid, erythrodiol and chondrillasterol. Their structures were elucidated on the basis of one and two dimensional NMR spectroscopic techniques, FABMS, ESMS and chemical evidence.     

Litter Cover Variability Affects Seedling Performance and Herbivory1

We assessed the effects of litter cover on herbivory and performance (annual survival and relative growth rate in height and leaf number) for established seedlings (≥9 cm tall, and ≥4 mo old), of four shade-tolerant, large-seeded, co-occurring Sapotaceae species. Seedlings were divided into three litter treatments: (1) litter addition, (2) control, and (3) continuous litter removal. The mean survival for all treatments in descending order were: Chrysophyllum pomiferum (89%), Pouteria pemviemis (84%), P. caimito (75%), and Micropholis venulosa (40%). For all variables, species differed significantly within litter treatments. In M. venulosa, survival and relative growth rate in leaf number significantly decreased with the removal of litter, whereas herbivory increased. Relative growth rate in height of P. peruviensis decreased significantly with litter removal, while the levels of herbivory were higher with the addition of litter. Conversely, litter quantity had no effect on the performance of C. pomiferum, but herbivory was lower in the removal treatment. Finally, in P. caimito, litter treatment did not affect performance or herbivory. Results suggest that differences in litter quantity differentially affect tree species with similar biology (i.e., large-seeds, shade tolerance) in life stages other than germination and early establishment. The variability in species' responses to litter might be an important factor in determining species richness, abundance, and distribution of tropical rain forest tree species at the seedling level.     

人心果和蛋黄果染色体核型分析

研究了山榄科的2种优稀热带果树--人心果及蛋黄果的染色体计数及其染色体形态与核型分析.结果表明:人心果体细胞染色体2n=2X=26,核型类型为2B型,核型公式为18m+8sm,染色体相对长度组成为2L+12M:+8M1+4S,不对称系数为61.71%;蛋黄果体细胞染色体2n=2X=28,核型类型为1A型.核型公式为26m+2sm,染色体相对长度组成为2L+10M2+16M1,不对称系数为59.193%.     

Modelling the known and unknown plant biodiversity of the Amazon Basin

Aims The overall aim of this study is to provide the data needed for Amazonian conservation and the sustainable management of the region. To this end I model the hypothetical distribution of plant species richness across the Amazon Basin, the distribution of the proportion of this species richness that can be accounted for by described species, and hence the distribution of the biodiversity which remains unknown. Location Amazonia, Neotropics. Methods Species richness across the Amazon Basin is estimated by comparing the occurrences of 1584 species of Magnoliophyta whose taxonomy and geographical distributions are relatively well known. These data are used to collate checklists for squares of 1° latitude by 1° longitude. Comparison of the checklists allows estimation of the relative expected diversity in the vicinity of each degree square. Summing the distributions of the hypothetical real ranges gives the proportion of the biodiversity that can be accounted for by described species. Subtraction of the second distribution from the first gives a distribution of the contribution to the overall biodiversity that the model predicts, potentially, results from as yet undescribed species. Results Collections documented in recent botanical monographs show an extremely biased distribution with the best knowledge being found in a very few relatively well‐collected areas. At the degree square level, this model predicts that gamma biodiversity in the Amazon Basin is uniformly high across most of the basin. The model predicts that four large areas of the basin are particularly poorly known, and that they should contain large numbers of uncollected species. Main conclusions The model presented here highlights the difficulties of quantifying Amazonian plant diversity and its distribution. The low density of collections, and especially their extremely clumped distribution, undermines confidence in theories that seek to explain the apparent distribution of biodiversity. The model's prediction is substantially different from published predictions of the distribution of alpha diversity. Testing of this model in the areas identified as lacunae would require collecting programmes designed to collect fertile material of rare species. If the model's predictions are approximately accurate, the plant biodiversity of the Amazon Basin is considerably underestimated.     

The relation between nickel and citric acid in some nickel-accumulating plants

A strong correlation has been found between the levels of nickel and citric acid in the leaves of 17 New Caledonian plant species which show a range of nickel-accumulating ability: Sebertia acuminata, Psychotria douarrei, Geissois pruinosa, Hybanthus austrocaledonicus, Hybanthus caledonicus, and 12 species of Homalium. Purified extracts of these plants contain nickel as a citrate complex. Three nickel-accumulating plants from beyond New Caledonia (Alyssum bertolonii, Alyssum serpyllifolium s.sp. lusitanicum and Pearsonia metallifera) do not contain unusually high levels of citrate, nor is citrate present in purified nickel-containing extracts of these species.