Knowledge about the origins and evolution of crop species represents an important prerequisite for efficient conservation and use of existing plant materials. This study was designed to solve the ongoing debate on the origins of the common bean by investigating the nucleotide diversity at five gene loci of a large sample that represents the entire geographical distribution of the wild forms of this species. Our data clearly indicate a Mesoamerican origin of the common bean. They also strongly support the occurrence of a bottleneck during the formation of the Andean gene pool that predates the domestication, which was suggested by recent studies based on multilocus molecular markers. Furthermore, a remarkable result was the genetic structure that was seen for the Mesoamerican accessions, with the identification of four different genetic groups that have different relationships with the sets of wild accessions from the Andes and northern Peru–Ecuador. This finding implies that both of the gene pools from South America originated through different migration events from the Mesoamerican populations that were characteristic of central Mexico

Together with the knowledge of the population structure, a critical aspect for the planning of association and/or population genomics studies is the level of linkage disequilibrium (LD) that characterizes the species and the population used for such an analysis. We have analyzed the population structure and LD in wild and domesticated populations of Phaseolus vulgaris L. using amplified fragment length polymorphism markers, most of which were genetically mapped in two recombinant inbred populations. Our results reflect the previous knowledge of the occurrence of two major wild gene pools of P. vulgaris, from which two independent domestication events originated, one in the Andes and one in Mesoamerica. The high level of LD in the whole sample was mostly due to the gene pool structure, with a much higher LD in domesticated compared to wild populations. In relation to association studies, our results also suggest that whole-genome-scan approaches are feasible in the common bean. Interestingly, an excess of inter-chromosomal LD was found in the domesticated populations, which suggests an important role for epistatic selection during domestication. Moreover, our results indicate the occurrence of a strong bottleneck in the Andean wild population before domestication, suggesting a Mesoamerican origin of P. vulgaris. Finally, our data support the occurrence of a single domestication event in Mesoamerica, and the same scenario in the Andes.

-The effect of the application of silicon to corn plants on the development of the fall armyworm Spodoptera frugiperda (J.E. Smith) was evaluated. Silicon treatment consisted in applying 3.2 ml of a sodium silicate solution [25-28% (w/v) SiO 2 ] plus 96.8 ml of water into the soil at 5, 10, 15, 20 and 25 days after emergence of corn plants kept in pots. Another group of plants were grown free of silicon. Larvae were fed on leaves obtained from silicon treated plants and their mortality at the end of the 2 nd larval instar, length of the larval and pupal period, and pupal weight were compared to those of larvae fed on normal leaves. No effect of silicon was observed on the length of larval and pupal phase, pupal weight and mortality of pupae. However, increased mortality and cannibalism were registered in groups of fall armyworm at the end of the 2 nd instar and greater mortality of the larvae was seen at the 2 nd and 6 th instars fed on silicon-treated corn plant leaves in comparison with the control. The jaws mandibles of fall armyworm at the 6 th instar showed marked wear on the incisor region when in contact with leaves with higher silicon content. Silicon application can make fall armyworm feeding difficult, causing higher mortality and cannibalism, thus increasing plant resistance to this species.KEY WORDS: Insecta, Zea mays, resistance, Integrate Pest Management.RESUMO -Este trabalho, objetivou avaliar o efeito da aplicação de silício em plantas de milho no desenvolvimento da lagarta-do-cartucho Spodoptera frugiperda (J.E. Smith). O tratamento com silício consistiu na aplicação de 3,2 ml de solução de silicato de sódio [25-28% (p/v) de SiO 2 ], mais 96,8 ml de água, via solo aos cinco dias, 10, 15, 20 e 25 dias após a emergência de plantas de milho mantidas em vasos. Outro grupo de plantas foi cultivado sem aplicação de silício. Avaliou-se o desenvolvimento de lagartas alimentadas com folhas de milho retiradas de plantas tratadas com silício, em comparação com lagartas alimentadas com folhas de milho não tratadas, registrando-se a mortalidade ao final do 2 o ínstar larval, a duração do período larval e pupal, a mortalidade larval e pupal e o peso de pupa. Não se observou efeito do silício na duração da fase larval e pupal, peso de pupa e na mortalidade de pupas. Entretanto, verificou-se maior mortalidade e aumento de canibalismo em grupos de lagartas ao final do 2 o ínstar, e maior mortalidade de lagartas individualizadas no 2 o e 6 o ínstares, quando foram alimentadas com folhas de plantas de milho tratadas com silício, em comparação com a testemunha. Observou-se que as mandíbulas das lagartas, nos seis ínstares, apresentaram desgaste acentuado na região incisora quando em contato com folhas com maior teor de silício. A aplicação de silício pode dificultar a alimentação de lagartas, causando aumento de mortalidade e canibalismo e, portanto, tornando as plantas de milho mais resistentes à lagarta-do-cartucho. PALAVRAS-CHAVE: Insecta, Zea mays, resistência, Manejo Integrado de Pragas.

Facioscapulohumeral muscular dystrophy (FSHD) progressively affects the facial, shoulder, and upper arm muscles and is associated with contractions of the polymorphic D4Z4 repeat array in 4q35. Recently, we demonstrated that FSHD alleles are hypomethylated at D4Z4. To study potential relationships between D4Z4 hypomethylation and both residual repeat size and clinical severity, we compared the clinical severity score with D4Z4 methylation in unrelated FSHD patients. Correcting the clinical severity score for age at examination improves the parameter to define clinical severity and provides further support for hypomethylation of FSHD alleles. However, a linear relationship between repeat size and clinical severity of the disease cannot be established. Interestingly, FSHD can be separated in two clinical severity classes: patients with residual repeat sizes of 10 to 20 kb are severely affected and show pronounced D4Z4 hypomethylation. In contrast, patients with repeat sizes of 20 to 31kb show large interindividual variation in clinical severity and D4Z4 hypomethylation. Because the majority of familial FSHD cases are represented in this interval and considering the overt variation in clinical severity in these familial cases, it thus is imperative to develop comprehensive allele-specific assays monitoring total D4Z4 methylation to investigate whether interindividual variation in D4Z4 methylation can be translated into a prognostic factor for clinical severity.

Facioscapulohumeral muscular dystrophy (FSHD) is an inherited disease, and although strongly suggested, a contribution of inflammation to its pathogenesis has never been demonstrated. In FSHD patients, we found by immunohistochemistry inflammatory infiltrates mainly composed by CD8(+) T cells in muscles showing hyperintensity features on T2-weighted short tau inversion recovery magnetic resonance imaging (T2-STIR-MRI) sequences. Therefore, we evaluated the presence of circulating activated immune cells and the production of cytokines in patients with or without muscles showing hyperintensity features on T2-STIR-MRI sequences and from controls. FSHD patients displaying hyperintensity features in one or more muscles showed higher CD8(+)pSTAT1(+), CD8(+)T-bet(+) T cells and CD14(+)pSTAT1(+), CD14(+)T-bet(+) cells percentages and IL12p40, IFNγ and TNFα levels than patients without muscles displaying hyperintense features and controls. Moreover, the percentages of CD8(+)pSTAT1(+), CD8(+)T-bet(+) and CD14(+)pSTAT1(+) cells correlated with the proportion of muscles displaying hyperintensity features at T2-STIR sequences. These data indicate that circulating activated immune cells, mainly CD8(+) T cells, may favour FSHD progression by promoting active phases of muscle inflammation.

Wild common bean (Phaseolus vulgaris L.) is distributed throughout the Americas from Mexico to northern Argentina. Within this range, the species is divided into two gene pools (Andean and Middle American) along a latitudinal gradient. The diversity of 24 wild common bean genotypes from throughout the geographic range of the species was described by using sequence data from 13 loci. An isolation-migration model was evaluated using a coalescent analysis to estimate multiple demographic parameters. Using a Bayesian approach, Andean and Middle American subpopulations with high percentage of parentages were observed. Over all loci, the Middle American gene pool was more diverse than the Andean gene pool (p sil ¼ 0.0089 vs 0.0068). The two subpopulations were strongly genetically differentiated over all loci (F st ¼ 0.29). It is estimated that the two current wild gene pools diverged from a common ancestor B111 000 years ago. Subsequently, each gene pool underwent a bottleneck immediately after divergence and lasted B40 000 years. The Middle American bottleneck population size was B46% of the ancestral population size, whereas the Andean was 26%. Continuous asymmetric gene flow was detected between the two gene pools with a larger number of migrants entering Middle American gene pool from the Andean gene pool. These results suggest that because of the complex population structure associated with the ancestral divergence, subsequent bottlenecks in each gene pool, gene pool-specific domestication and intense selection within each gene pool by breeders; association mapping would best be practised within each common bean gene pool.

Molecular linkage maps are an important tool for gene discovery and cloning, crop improvement, further genetic studies, studies on diversity and evolutionary history, and cross-species comparisons. Linkage maps differ in both the type of marker and type of population used. In this study, gene-based markers were used for mapping in a recombinant inbred (RI) population of Phaseolus vulgaris L. P. vulgaris, common dry bean, is an important food source, economic product, and model organism for the legumes. Gene-based markers were developed that corresponded to genes controlling mutant phenotypes in Arabidopsis thaliana, genes undergoing selection during domestication in maize, and genes that function in a biochemical pathway in A. thaliana. Sequence information, including introns and 3' UTR, was generated for over 550 genes in the two genotypes of P. vulgaris. Over 1,800 single nucleotide polymorphisms and indels were found, 300 of which were screened in the RI population. The resulting LOD 2.0 map is 1,545 cM in length and consists of 275 gene-based and previously mapped core markers. An additional 153 markers that mapped at LOD <1.0 were placed in genetic bins. By screening the parents of other mapping populations, it was determined that the markers were useful for other common Mesoamerican × Andean mapping populations. The location of the mapped genes relative to their homologs in Arabidopsis thaliana (At), Medicago truncatula (Mt), and Lotus japonicus (Lj) were determine by using a tblastx analysis with the current psedouchromosome builds for each of the species. While only short blocks of synteny were observed with At, large-scale macrosyntenic blocks were observed with Mt and Lj. By using Mt and Lj as bridging species, the syntenic relationship between the common bean and peanut was inferred.

Given the susceptibility of tomato plants to pests, the aim of the present study was to understand how hormones are involved in the formation of tomato natural defences against insect herbivory. Tomato hormone mutants, previously introgressed into the same genetic background of reference, were screened for alterations in trichome densities and allelochemical content. Ethylene, gibberellin, and auxin mutants indirectly showed alteration in trichome density, through effects on epidermal cell area. However, brassinosteroids (BRs) and jasmonates (JAs) directly affected trichome density and allelochemical content, and in an opposite fashion. The BR-deficient mutant dpy showed enhanced pubescence, zingiberene biosynthesis, and proteinase inhibitor expression; the opposite was observed for the JA-insensitive jai1-1 mutant. The dpy x jai1-1 double mutant showed that jai1-1 is epistatic to dpy, indicating that BR acts upstream of the JA signalling pathway. Herbivory tests with the poliphagous insect Spodoptera frugiperda and the tomato pest Tuta absoluta clearly confirmed the importance of the JA-BR interaction in defence against herbivory. The study underscores the importance of hormonal interactions on relevant agricultural traits and raises a novel biological mechanism in tomato that may differ from the BR and JA interaction already suggested for Arabidopsis.