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Diversity and genetic relationship in forty landraces of Cucurbita spp. collected at small farms in Rio de Janeiro, Brazil, were analyzed by RAPD and ISSR markers, using 20 and 15 primers, respectively. Both markers were efficient to cluster the accessions separating among species, but not so much to the detection of intra-specific variability, considering the event of different pairs of accessions comprising null genetic distances observed for both markers in C. moschata. Low values observed for genetic distance among the C. moschata landraces showed that most likely genetic losses is in progress in that region of cultivation due to anthropic and market pressure, which are stimulating the small farmers to abandon their local varieties in order to use commercial seeds, including hybrids, which is causing risk of genetic erosion.

The genus Dimorphandra has distinguish relevance considering either medicinal or biodiversity aspects because it includes two species that are economically important flavonoids sources for pharmachemical industry (D. mollis Benth. and D. gardneriana Tul.), and species endemic to Brazil, such as D. jorgei Silva and D. wilsonii Rizz., threatened by extinction. In order to evaluate variability among accessions of D. mollis (fava-d'anta), D. gardneriana and D. wilsonii, it was collected fruit from individual plants from three Brazilian states in a total of 57 accessions, which were analyzed with RAPD markers. It was used 20 seeds per progeny; the DNA was extracted from fully-formed young leaves, which were collected in bulk. The data were analyzed using a binary matrix, in which the score one represented presence of a band and zero, absence. The similarity matrix was developed by using the arithmetic complement of the Jaccard index, later grouped based on the Neighbor Joining algorithm. It was found considerable intra and inter specific variability in Dimorphandra spp., which were separated into four groups. Though genetic variability was found, the collecting trips showed that most of these areas are subject to loss of genetic resources of fava-d'anta due to the following factors: continuous anthropic activity, propensity for natural fires, and loss of natural seed dispersers (large fruit-eating mammals). Therefore, protections of these areas and ex situ conservation are essentials for the maintenance of genetic variability of these species. O gênero Dimorphandra tem grande relevância, sobretudo nos aspectos medicinais e de biodiversidade, por incluir duas espécies que são importantes economicamente como fontes de flavonoides para indústria farmacoquímica (D. mollis Benth. e D. gardneriana Tull.), e espécies endêmicas do Brasil, como a D. jorgei Silva e D. wilsonii Rizz., sendo esta ameaçada de extinção. Objetivando avaliar a variabilidade entre acessos de D. mollis, D. gardneriana e D. wilsonii, foram realizadas coletas de frutos separados por planta em três estados brasileiros em um total de 57 acessos que foram analisados por meio da técnica RAPD. Utilizaram-se vinte sementes por progênie e o DNA, extraído de folhas definitivas, jovens, e coletadas em bulk. Os dados foram analisados utilizando-se uma matriz de dados binários. Para formação da matriz de dissimilaridade, foi utilizado o complemento aritmético do Índice de Jaccard e posteriormente o agrupamento pelo algoritmo de Neighbor Joining. O estudo revelou que existe variabilidade entre e dentro das espécies de Dimorphandra spp., o qual formou quatro grupos. Apesar da variabilidade genética constatada, as expedições de coleta demonstraram que a maioria das áreas amostradas está sujeita a perdas de recursos genéticos de fava-d'anta devido aos seguintes fatores: ocorrência de ação antrópica contínua; propensão a incêndios naturais; e diminuição dos dispersores naturais de sementes (grandes mamíferos frugíveros). Assim, a proteção destas áreas e a conservação ex situ, são primordiais para manutenção da variabilidade genética dessas espécies.

Heterosis has been exploited in Capsicum annuum commercial hybrids; however, the use of heterosis in C. baccatum still remains to be explored, and studies related to the genetics and breeding of this species are scarce. The present study aimed to estimate the combining ability of five parents of C. baccatum var. pendulum , representatives of two distinct types of fruits (namely, lady's finger and cambuci), to calculate heterosis and to evaluate the agronomic potential of the hybrids for yield and fruit quality. The hybrids were produced from a complete diallel without reciprocals. The parents and hybrids were evaluated under field conditions in a randomized block design with three replications, and the following traits were assessed: number of fruits per plant, fruit weight, yield per plant, fruit length, fruit diameter and soluble solids. All traits were significant for general and specific combining ability, indicating that additive and non-additive effects are involved in the genetic control of these traits. The hybrid combinations between the types lady's finger and cambuci provided elongated fruits with smaller diameters and greater weight compared with the parents of the cambuci type. However, these factors did not lead to a significant increase in the yield per plant due to the decreased number of fruits except in hybrid UENF 1616 x UENF 1732. Considering only the parents and hybrids within each type of fruit, the genitor UENF 1624 (lady's finger) and the hybrid UENF 1639 x UENF 1732 (cambuci x cambuci) stood out for achieving a high yield per plant.

We investigated inheritance of resistance to Pepper yellow mosaic virus (PepYMV) in Capsicum baccatum var. pendulum accessions UENF 1616 (susceptible) crossed with UENF 1732 (resistant). Plants from generations P1, P2, F1, F2, BC1:1, and BC1:2 were inoculated and the symptoms were evaluated for 25 days. Subsequently, an area under the disease progress curve was calculated and subjected to generation means analysis. Only the average and epistatic effects were significant. The broad and narrow sense heritability estimates were 35.52 and 21.79%, respectively. The estimate of the minimum number of genes that control resistance was 7, indicating that resistance is polygenic and complex. Thus, methods to produce segregant populations that advocate selection in more advanced generations would be the most appropriate to produce chili pepper cultivars resistant to PepYMV.