The Relationship between Population Structure and Aluminum Tolerance in Cultivated Sorghum

Background: Acid soils comprise up to 50% of the world's arable lands and in these areas aluminum (Al) toxicity impairs root growth, strongly limiting crop yield. Food security is thereby compromised in many developing countries located in tropical and subtropical regions worldwide. In sorghum, SbMATE, an Al-activated citrate transporter, underlies the Alt(SB) locus on chromosome 3 and confers Al tolerance via Al-activated root citrate release. Methodology: Population structure was studied in 254 sorghum accessions representative of the diversity present in cultivated sorghums. Al tolerance was assessed as the degree of root growth inhibition in nutrient solution containing Al. A genetic analysis based on markers flanking Alt(SB) and SbMATE expression was undertaken to assess a possible role for Alt(SB) in Al tolerant accessions. In addition, the mode of gene action was estimated concerning the Al tolerance trait. Comparisons between models that include population structure were applied to assess the importance of each subpopulation to Al tolerance. Conclusion/Significance: Six subpopulations were revealed featuring specific racial and geographic origins. Al tolerance was found to be rather rare and present primarily in guinea and to lesser extent in caudatum subpopulations. Alt(SB) was found to play a role in Al tolerance in most of the Al tolerant accessions. A striking variation was observed in the mode of gene action for the Al tolerance trait, which ranged from almost complete recessivity to near complete dominance, with a higher frequency of partially recessive sources of Al tolerance. A possible interpretation of our results concerning the origin and evolution of Al tolerance in cultivated sorghum is discussed. This study demonstrates the importance of deeply exploring the crop diversity reservoir both for a comprehensive view of the dynamics underlying the distribution and function of Al tolerance genes and to design efficient molecular breeding strategies aimed at enhancing Al tolerance.

DEVELOPMENT OF A NOVEL SET OF MICROSATELLITE MARKERS FOR CASTOR BEAN, RICINUS COMMUNIS (EUPHORBIACEAE)

Premise of study: Microsatellite primers were developed for castor bean (Ricinus communis L.) to investigate genetic diversity and population structure, and to provide support to germplasm management. Methods and Results: Eleven microsatellite loci were isolated using an enrichment cloning protocol and used to characterize castor bean germplasm from the collection at the Instituto Agronomico de Campinas (IAC). In a survey of 76 castor bean accessions, the investigated loci displayed polymorphism ranging from two to five alleles. Conclusions: The information derived from microsatellite markers led to significant gains in conserved allelic richness and provides support to the implementation of several molecular breeding strategies for castor bean.

Development and characterization of microsatellite markers for turmeric (Curcuma longa)

P>Curcuma longa L. is a sterile, triploid, vegetatively-propagated crop cultivated mainly in Southeast Asia. When dried rhizomes are ground, the resulting yellow powder is used by the food industry as a natural food dye. Moreover, many pharmacological compounds have broadened the commercial application of the crop. However, conventional breeding is difficult and hence, improvement has been limited to germplasm selection. To better utilize the germplasm collections and facilitate genotype selection, a total of 17 polymorphic microsatellite loci were developed using a CT/GT/CTT enriched genomic library. All microsatellites resulted in amplified PCR products, showing a banding pattern of 2-11 polymorphic bands per locus, enabling genotype discrimination. These results can be used in further studies aimed at characterizing C. longa genetic resource collections and also to improve breeding strategies.

Genetic variation for anatomic traits and volume shrinkage and their correlation with wood basic density in an Eucalyptus camaldulensis Dehn base population

Eucalyptus camaldulensis has great importance in Brazil because of their phenotypic plasticity for different environmental conditions, as soils, altitudes and rainfall. This study is an investigation of a base population of E. camaldulensis from Australia through a progeny test implanted in Selviria, MS. The trial was established in a randomized block design, with 25 families and 60 replications of single tree plots. Genetic parameters for anatomic traits and volume shrinkage were estimated, as well as their correlations with wood basic density. No significant differences among progenies were observed for the traits studied. The additive genetic variation coefficient at individual and among progeny levels ranged from low (0.26%) to high (16.98%). The narrow sense heritability at individual and family means levels also ranged from low (0.01) to high (0.87). This indicates that some traits are under strong genetic control and can be improved by selection. In the present situation, in order to attain the highest genetic gains, the sequential selection among and within progeny would be recommended.

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.

Energy substrate utilization during nightly vocal activity in three species of Scinax (Anura/Hylidae)

Anuran amphibians exhibit different patterns of energy substrate utilization that correlate with the intensity of vocal and locomotor activities. Given the remarkable differences among species in breeding and feeding strategies, and the different ways energy is used in the whole animal, the suggested correlations between calling and locomotor behavior and the level of energy substrates in the muscles responsible for such activities are more complex than previously reported. We explored the relationships between calling and locomotor behavior and energy supply to trunk and hindlimb muscles, respectively, within the ecologically diverse tree-frog genus Scinax. Specifically, we measured the relative amount of carbohydrates and lipids in these two groups of muscles, and in the liver of three species of Scinax that differ in vocal and locomotor performance, and compared our results with those of two other species for which comparable data are available. We also compared the contents of lipids and carbohydrates of conspecific males collected at the beginning and after 4 h of calling activity. The stomach content to potential feeding opportunities across species was also assessed in both groups of males. Scinax hiemalis and S. rizibilis exhibit comparatively low and episodic calling during long periods of activity whereas S. crospedospilus calls at higher rates over shorter periods. Male S. hiemalis had highest levels of trunk muscle glycogen followed by those of S. rizilbilis and S. crospedospilus, respectively. There was no correlation between total lipid content in trunk muscle and calling rate among different species, suggesting that other metabolic aspects may be responsible for the energetic support for vocal activity. The levels of lipids and carbohydrates in trunk and hindlimb muscles and liver of males collected at the beginning and 4 h into the calling period were similar across species, so the extent of energetic reserves does not appear to constrain vocal or locomotor activity. Finally, we found exceptionally high levels of carbohydrates and lipids in the liver of S. rizibilis, a trait perhaps related to a long and demanding breeding period.

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.

Inbreeding levels in Northeast Brazil: strategies for the prospecting of new genetic disorders

A new autosomal recessive genetic condition, the SPOAN syndrome (an acronym for spastic paraplegia, optic atrophy and neuropathy syndrome), was recently discovered in an isolated region of the State of Rio Grande do Norte in Northeast Brazil, in a population that was identified by the IBGE (Brazilian Institute of Geography and Statistics) as belonging to the Brazilian communities with the highest rates of "deficiencies" (Neri, 2003), a term used to describe diseases, malformations, and handicaps in general. This prompted us to conduct a study of consanguinity levels in five of its municipal districts by directly interviewing their inhabitants. Information on 7,639 couples (corresponding to about 40% of the whole population of the studied districts) was obtained. The research disclosed the existence of very high frequencies of consanguineous marriages, which varied from about 9% to 32%, suggesting the presence of a direct association between genetic diseases such as the SPOAN syndrome, genetic drift and inbreeding levels. This fact calls for the introduction of educational programs for the local populations, as well as for further studies aiming to identify and characterize other genetic conditions. Epidemiological strategies developed to collect inbreeding data, with the collaboration of health systems available in the region, might be very successful in the prospecting of genetic disorders.

Karyotypic analyses and morphological comments on the endemic and endangered Brazilian painted tree rat Callistomys pictus (Rodentia, Echimyidae)

The genus Callistomys belongs to the rodent family Echimyidae, subfamily Echimyinae, and its only living representative is Callistomys pictus, a rare and vulnerable endemic species of the state of Bahia, Brazil. Callistomys has been previously classified as Nelomys, Loncheres, Isothrix and Echimys. In this paper we present the karyotype of Callistomys pictus, including CBG and GTG-banding patterns and silver staining of the nucleolus organizer regions (Ag-NORs). Comments on Callistomys pictus morphological traits and a compilation of Echimyinae chromosomal data are also included. Our analyses revealed that Callistomys can be recognized both by its distintinctive morphology and by its karyotype.

Kelp gulls, Larus dominicanus (Aves: Laridae), breeding in Keller Peninsula, King George Island, Antarctic Peninsula

We examined the distribution, abundance and density of the Kelp Gull, Larus dominicanus (Lichtenstein, 1823), at Keller Peninsula on two occasions during the breeding season of 2007-2008 (once for incubation and once for chick stages) and compared our results with previously published data. We present information on the number of eggs, incubation success, and initial development of L. dominicanus chicks in the studied sites. The abundance and density of the species has remained statistically similar in Keller Peninsula over the last 30 years (since 1978-1979). Although the abundance and density were almost unchanged, we recorded alterations in the occupation of the breeding areas by L. dominicanus, mainly the abandonment of breeding sites in the eastern portion of Keller Peninsula. The results of the present study compared with similar previous investigations on the abundance of L. dominicanus indicate that the populations have been in equilibrium over the years.

The ichthyofauna of upper rio Capivari: defining conservation strategies based on the composition and distribution of fish species

Although the rio Capivari basin is recognized as an area of great importance for the ichthyofauna, it lacks virtually every basic requirement for the definition of appropriate conservation strategies, since not even its species composition is known. The objective of this work is to determine the composition and distribution of fish species in the upper rio Capivari basin, relating them to the local physical features, and to evaluate the effectiveness of proposed conservations units, delimited based on areas of native vegetation remains, on the conservation of local ichthyofauna. During 2007, 50 different watercourses were sampled with gillnets, cast nets and kick nets. A total of 1308 individuals belonging to 41 species were captured. Degree of conservation, altitude and width were the parameters that best explained fish species richness. Considering the recently proposed boundaries for potential conservation units in the region only 15 or 20 out of 41 species would be found in the State Park and Environmental Protection Area respectively. In practice, the proposed conservation units would not be effective tools for fish conservation, since it would be located in mountainous areas of high altitude, of headwaters streams and where few species are found. In such context, the conservation of specific stretches of larger rivers is critical.

Recommendations for folate intake in women: implications for public health strategies

Folate deficiency has been associated with anemia and other adverse outcomes in pregnancy such as neural tube defects. The current recommendations for prevention of such outcomes are difficult to achieve through diet only, and folic acid supplementation and food fortification are feasible public health strategies. However, it is necessary to determine the usual diet and supplement use among women of reproductive age, including an accurate assessment of other dietary micronutrients. In addition to the beneficial effects observed in randomized clinical trials, health risks to the population have also been widely evaluated and discussed in the scientific community: for a minority to benefit from fortification programs, many are exposed to high folic acid intake levels.

Observations on Haemagogus janthinomys Dyar (Diptera: Culicidae) and other mosquito populations within tree holes in a gallery forest in the northwestern region of Sao Paulo state, Brazil

In 2000, an outbreak of sylvatic yellow fever possibly occurred in gallery forests of the Grande river in the Paraná basin in the northwestern region of São Paulo state. The aim of this study was to obtain information on the bionomics of Haemagogus and other mosquitoes inside tree holes in that area. Eighteen open tree holes were sampled for immature specimens. Adults were collected twice a month in the forest in Santa Albertina county from July 2000 to June 2001. The seasonal frequency of fourth instars was obtained by the Williams geometric mean (Mw), while the adult frequency was estimated either by hourly arithmetic or the Williams' means. Cole's index was applied to evaluate larval inter-specific associations. Among the ten mosquito species identified, the most abundant was Aedes terrens Walker followed by Sabethes tridentatus Cerqueira and Haemagogus janthinomys Dyar. Larval and adult abundance of these species was higher in summer than in winter. Although larval abundance of Hg. janthinomys peaked in the rainy season, correlation with rainfall was not significant. Six groups of larval associations were distinguished, one of which the most positively stable. The Hg. janthinomys and Ae. terrens association was significant, and Limatus durhamii Theobald was the species with most negative associations.

Association of the borer Spermophthorus apuleiae (Coleoptera; Curculionidae; Scolytinae) with the "pau-ferro" tree Caesalpinia ferrea (Leguminosae)

The weevil subfamily Scolytinae includes beetles which may feed on the bark, trunk or roots of both live and dead trees and are sometimes considered forest and silvicultural pests. Less frequently, some species feed on seeds and may be cause economic losses when associated to plant cultivars. Spermophthorus apuleiae Costa-Lima is a Neotropical Scolytinae formerly recorded to be "associated" with seeds of Caesalpinia ferrea var. leiostachya Benth, a Brazilian tree popularly known in Portuguese as "pau-ferro". Hitherto, it was not clear whether these beetles actually feed on the seeds of that plant. In order to investigate the ability of S. apuleiae to feed on seeds of "pau-ferro", observations were done and colonies of these beetles were established. Both in the field and in captivity the beetles were not observed feeding on the seeds. Even when beetles were exposed to seeds as the only source of food they were incapable of boring or eating the seeds and died. Our data therefore suggest that S. apuleiae is a frugivorous species which peculiarly does not eat seeds of "pau-ferro".

Resprouting from roots in four Brazilian tree species

Previous studies pointed out that species richness and high density values within the Leguminosae in Brazilian forest fragments affected by fire could be due, at least partially, to the high incidence of root sprouting in this family. However, there are few Studies of the factors that induce root sprouting in woody plants after disturbance. We investigated the bud formation on root cuttings, and considered a man-made disturbance that isolates the root from the shoot apical dominance of three Leguminosae (Bauhinia forficata Link., Centrolobium tomentosum Guill. ex Benth, and Inga laurina (Sw.) Willd) and one Rutaceae (Esenbeckia febrifuga (St. Hit.) Juss. ex Mart.). All these species resprout frequently after fire. We also attempted to induce bud formation on root systems by removing the main trunk, girdling or sectioning the shallow lateral roots from forest tree species Esenbeckia febrifuga and Hymenaea courbaril L. We identified the origin of shoot primordia and their early development by fixing the samples in Karnovsky solution, dehydrating in ethyl alcohol series and embedding in plastic resin. Serial sections were cut on a rotary microtome and stained with toluidine blue O. Permanent slides were mounted in synthetic resin. We observed different modes of bud origin on root cuttings: close to the vascular cambium (C. tomentosum), from the callus (B. forficata and E febrifuga) and from the phloematic parenchyma proliferation (L laurina). Fragments of B. forficala root bark were also capable of forming reparative buds from healing phellogen formed in callus in the bark's inner side. In the attempt of bud induction on root systems, Hymenaea courbaril did not respond to any of the induction tests, probably because of plant age. However, Esenbeckia febrifuga roots formed suckers when the main trunk was removed or their roots were sectioned and isolated from the original plant. We experimentally demonstrated the ability of four tree species to resprout from roots after disturbance. Our results suggest that the release of apical dominance enables root resprouting in the studied species. Rev. Biol. Trop. 57 (3): 789-800. Epub 2009 September 30.