Brazil and Argentina have a combined soybean area of 53.6 million hectares, which accounts for over half of the total global production. The soybean crop in South America extends from latitude 8–10° S to 32–36° S. Such a vast, almost contiguous area imposes a serious sanitary risk to the crop. Currently, the prevalence of anthracnose is increasing, with recurring reports of severe epidemics and expressive yield losses. Soybean anthracnose is mainly associated with Colletotrichum truncatum, although other Colletotrichum species have also been reported as causal agents of this disease. Knowledge about the morphological, cultural, and molecular variability of C. truncatum in South America is crucial for disease management. Here, we present data on the molecular, morphological, biological, cultural, and pathogenicity of C. truncatum isolates collected in Brazil and Argentina. Light microscopy and randomly-amplified polymorphic DNA (RAPD) analysis were used for estimating the variability of isolates. Colletotrichum truncatum displayed three types of conidiogenesis, viz. conidial formation from conidiogenous cells on hyphal extremities, in conidiomas in acervuli, and directly from fertile setae (a mechanism yet-unreported for C. truncatum). RAPD profiling was effective in revealing the genetic diversity among C. truncatum isolates. The intra-group similarity was greater among the Argentinian isolates when compared to the Brazilian group. Furthermore, the results indicated a strong correlation between geographical origin and molecular grouping, with the exclusive or semi-exclusive assembling of Brazilian and Argentinian isolates in distinct clades. Finally, a preliminary account of the reaction of soybean accessions to C. truncatum is also included.

A complex of begomoviruses (Geminiviridae) can cause severe tomato yield losses in the neotropics. Here, next-generation sequencing was employed for large-scale assessment of single-stranded (ss)DNA virus diversity in tomatoes either harboring or lacking the large-spectrum begomovirus tolerance Ty-1 gene. Individual leaf samples exhibiting begomovirus-like symptoms (n = 107) were field-collected, circular DNA-enriched, subdivided into pools (with and without Ty-1), and Illumina-sequenced. Virus-specific PCR and Sanger dideoxy sequencing validations confirmed 15 distinct ssDNA virus/subviral agents (occurring mainly in mixed infections), which highlight the potential drawbacks of employing virus-specific resistance in tomato breeding. More viruses (14 versus 6 species) were observed in tomatoes without the Ty-1 gene. A gemycircularvirus (Genomoviridae), a new alpha-satellite, and two novel Begomovirus species were identified exclusively in samples without the Ty-1 gene. A novel begomovirus was found only in the Ty-1 pool, being the only species associated with severe symptoms in Ty-1 plants in our survey. Our work is the first step towards the elucidation of the potential begomovirus adaptation to Ty-1 and its specific filtering effects on a subset of ssDNA viral/subviral agents.

The correct use of hydrogels in some situations can increase seedling survival rates, plant growth, and the water-retention capacity of the growing medium. A technique for the production of a nanocomposite hydrogel using calcium montmorillonite (NC-MMt) was recently developed. However, additional research is necessary in order to validate this innovative input, particularly for the production of vegetable crops seedlings. In this context, the main objective of the present study was to evaluate the growth and development of seedlings, tomato hybrid ‘BRS Nagai’, in substrates containing different amendments of hydrogel NC-MMt. The trial was conducted in a 3x3 factorial arranged in a complete randomized blocks design, with three replications. Three substrates (peat moss, pine bark, and coconut peat) corresponded to the first factor and three rates of the NC-MMt hydrogel (0%= R1, 1.5%= R2 and 2.0%= R3, on a w/w basis) corresponded to the second factor. Each plot was composed of 16 plants that were assessed after three weeks. Overall, peat moss-based and pine bark-based substrates resulted in higher values for most of the analyzed traits: plant emergency percentage, plant height, stem diameter, leaf area, plant height/shoot dry weight ratio, root dry weight, shoot dry weight/root dry weight ratio and the Dickinson Quality Index. Rates of NC-MMt hydrogel displayed significant responses only to root superficial area and root volume. NC-MMt hydrogel amendment (mainly 1.5%) combined with specific substrates (mainly peat moss-based substrate) was able to improve the growth of ‘BRS Nagai’ tomato seedlings, with no observed toxic effects.

Eggplant (Solanum melongena L.) and scarlet eggplant (S. aethiopicum L.) are economically important vegetable crops in warm regions of Brazil. Samples of the eggplant cultivars ‘Napoli’ and ‘Ciça’ with interveinal yellowing in the older leaves similar to that induced by criniviruses were collected in fields heavily colonized by Bemisia tabaci MEAM-1 species in Canguçu–Rio Grande do Sul State in February 2013 (isolate named as CR-131) and Formosa–Goiás State in April 2015 (CR-173). Scarlet eggplants cv. ‘Comprido’ showing identical symptoms were also sampled in Venda Nova do Imigrante–Espírito Santo State in April 2013 (CR-148), Bragança Paulista–São Paulo State in June 2013 (CR-155), and Brasília–Federal District in June 2015 (CR-193). In order to check for infection by the criniviruses Tomato chlorosis virus (ToCV) and Tomato infectious chlorosis virus (TICV), RT-PCR assays were carried out (with one sample per site) using the primer pair HS-11/HS-12. All symptomatic samples displayed a 587-bp amplicon, ...