eThe incidence of begomovirus infections in crop plants sharply increased in Brazil during the 1990s following the introduction of the invasive B biotype of the whitefly vector, Bemisia tabaci. It is believed that this biotype transmitted begomoviruses from noncultivated plants to crop species with greater efficiency than indigenous B. tabaci biotypes. Either through rapid host adaptation or selection pressure in genetically diverse populations of noncultivated hosts, over the past 20 years various previously unknown begomovirus species have became progressively more prevalent in cultivated species such as tomato. Here we assess the genetic structure of begomovirus populations infecting tomatoes and noncultivated hosts in southeastern Brazil. Between 2005 and 2010, we sampled and sequenced 126 DNA-A and 58 DNA-B full-length begomovirus components. We detected nine begomovirus species in tomatoes and eight in the noncultivated host samples, with four species common to both tomatoes and noncultivated hosts. Like many begomoviruses, most species are obvious interspecies recombinants. Furthermore, species identified in tomato have probable parental viruses from noncultivated hosts. While the population structures of five well-sampled viral species all displayed geographical subdivision, a noncultivated host-infecting virus was more genetically variable than the four predominantly tomato-infecting viruses.

A survey of begomoviruses infecting leguminous weeds (family Fabaceae) was carried out in four states of northeastern Brazil. A total of 26 full-length begomovirus components (19 DNA-A and seven DNA-B, with three pairs of cognate A and B components) were amplified using rolling-circle amplification, then cloned and sequenced. Sequence analysis indicated the presence of six species, four of them novel. In phylogenetic analysis five of the viruses clustered with other Brazilian begomoviruses, but one of them (Euphorbia yellow mosaic virus, EuYMV) clustered with viruses from other countries in Central and South America. Evidence of recombination was found among isolates of Macroptilium yellow spot virus (MaYSV). The MaYSV population had a high degree of genetic variability. Macroptilium lathyroides was revealed as a common host for several of these viruses, and could act as a mixing vessel from which recombinant viruses could emerge. The results indicate that leguminous weeds are reservoirs of several begomoviruses in Brazil, and could play a significant role in begomovirus epidemics, both as inoculum sources and as sources of emerging novel viruses.

The tropical tree Bixa orellana L. produces a range of secondary metabolites which biochemical and molecular biosynthesis basis are not well understood. In this work we have characterized a set of ESTs from a non-normalized cDNA library of B. orellana seeds to obtain information about the main developmental and metabolic processes taking place in developing seeds and their associated genes. After sequencing a set of randomly selected clones, most of the sequences were assigned with putative functions based on similarity, GO annotations and protein domains. The most abundant transcripts encoded proteins associated with cell wall (prolyl 4-hydroxylase), fatty acid (acyl carrier protein), and hormone/flavonoid (2OG-Fe oxygenase) synthesis, germination (MADS FLC-like protein) and embryo development (AP2/ERF transcription factor) regulation, photosynthesis (chlorophyll a-b binding protein), cell elongation (MAP65-1a), and stress responses (metallothionein- and thaumatin-like proteins). Enzymes were assigned to 16 different metabolic pathways related to both primary and secondary metabolisms. Characterization of two candidate genes of the bixin biosynthetic pathway, BoCCD and BoOMT, showed that they belong, respectively, to the carotenoid-cleavage dioxygenase 4 (CCD4) and caffeic acid O-methyltransferase (COMT) families, and are up-regulated during seed development. It indicates their involvement in the synthesis of this commercially important carotenoid pigment in seeds of B. orellana. Most of the genes identified here are the first representatives of their gene families in B. orellana.