[show abstract][hide abstract] ABSTRACT: We estimated genetic gains for popcorn varieties using selection indexes in a fourth cycle of intrapopulation recurrent selection developed in the campus of the Universidade Estadual do Norte Fluminense. Two hundred full-sib families were obtained from the popcorn population UNB-2U of the third recurrent selection cycle. The progenies were evaluated in a randomized block design with two replications at sites in two different environments: the Colégio Estadual Agrícola Antônio Sarlo, in Campos dos Goytacazes, and the Empresa de Pesquisa Agropecuária do Estado do Rio de Janeiro (PESAGRO-RIO), in Itaocara, both in the State of Rio de Janeiro. There were significant differences between families within sets in all traits, indicating genetic variability that could be exploited in future cycles. Thirty full-sib families were selected to continue the program. The selection indexes used to predict the gains were those of Mulamba and Mock, Smith and Hazel. The best results were obtained with the Mulamba and Mock index, which allowed the prediction of negative gains for the traits number of diseased ears and ears attacked by pests, number of broken plants and lodging, as well as ears with poor husk cover. It also provided higher gains for popping expansion and grain yield than with the other indexes, giving values of 10.55 and 8.50%, respectively, based on tentatively assigned random weights.
[show abstract][hide abstract] ABSTRACT: Pepper species of the genus Capsicum have been cultivated over centuries, producing both pungent and sweet fruit; the pungency is caused by alkaloids called capsaicinoids. Among the five cultivated species, Capsicum chinense is one of the most popular, being native to the Amazon basin. This species is characterized by a wide variety of fruit sizes, shapes and colors, with different capsaicinoid content. In addition, fruits are rich in vitamins A and C. Despite the importance of this plant as a spice and its medicinal uses, research on its genetic variability and potential for breeding programs is still incipient. We investigated the genetic control of some traits through diallel analysis with the objective of introgressing these traits into cultivated varieties. For the diallel analysis, the progeny of crosses between peppers with pungent and sweet fruits, together with the parents, were grown in pots under greenhouse conditions. The fruits were harvested and analyzed for the traits total fresh fruit mass, total dry fruit mass, percentage dry matter, total soluble solids, vitamin C content, fruit pungency, and number of seeds per fruit. Genetic variability was detected for all traits. In the diallel analysis, the additive-dominant model was considered to be adequate for total fresh fruit mass, percentage dry matter, total soluble solids, and vitamin C content. Additive genetic effects and dominance were found for all traits; consequently, breeding for improvement of these fruit traits would be viable.
[show abstract][hide abstract] ABSTRACT: We estimated the genetic diversity of 49 accessions of the hot pepper species Capsicum chinensis through analyses of 12 physicochemical traits of the fruit, eight multi-categorical variables, and with 32 RAPD primers. Data from the physicochemical traits were submitted to analysis of variance to estimate the genetic parameters, and their means were clustered by the Scott-Knott test. The matrices from the individual and combined distance were estimated by multivariate analyses before applying Tocher's optimization method. All physicochemical traits were examined for genetic variability by analysis of variance. The responses of these traits showed more contribution from genetic than from environmental factors, except the percentage of dry biomass, content of soluble solids and vitamin C level. Total capsaicin had the greatest genetic divergence. Nine clusters were formed from the quantitative data based on the generalized distance of Mahalanobis, using Tocher's method; four were formed from the multi-categorical data using the Cole-Rodgers coefficient, and eight were formed from the molecular data using the Nei and Li coefficient. The accessions were distributed into 14 groups using Tocher's method, and no significant correlation between pungency and origin was detected. Uni- and multivariate analyses permitted the identification of marked genetic diversity and fruit attributes capable of being improved through breeding programs.
[show abstract][hide abstract] ABSTRACT: Cocona (Solanum sessiliflorum Dunal) is a solanaceous shrub native to the Amazon region that produces an edible fruit. This species has numerous advantages, particularly a high nutritional value and productivity. However, due to irregular germination and rapid loss of seed viability, there are few plantations for production on a large scale. Development of alternative propagation strategies is essential for the production of homogeneous seedlings of genotypes with superior agronomic performance. We developed techniques for in vitro regeneration of the cocona varieties Santa Luzia and Thaís for large-scale production of healthy plantlets. Twenty days after seeding, seedling segments germinated in vitro were used as explant sources. Three successive experiments were performed: one to test the effect of the explant source and combinations of two growth regulators, auxin (indole acetic acid, IAA) and kinetin (KIN), on the morphogenetic response; another to investigate the effect of the combination of growth regulators on the morphogenetic response of hypocotyl segments, and another to evaluate how sucrose concentration affects the development of adventitious shoots. The best shoot induction was obtained using hypocotyl segments and stem apices, while rhizogenesis was greatest in leaves with a petiole. The number of adventitious shoots per explant on hypocotyl segments increased with 10 and 20 mg/L KIN, combined with 0.02 mg/L IAA in the variety Santa Luzia. Sucrose combined with these growth regulator levels increased the average number of calli; these were optimally produced when 45 g/L sucrose and 0.01 mg/L IAA + 20 mg/L KIN were applied. Only sucrose concentration influenced shoot proliferation in the two S. sessiliflorum varieties, with a maximum at 17.5 g/L.
[show abstract][hide abstract] ABSTRACT: Flower buds from peach tomato plants ( Solanum sessiliflorum ) were collected to the establishment of a protocol of calli induction from anthers culture. Aseptic cultures were achieved after the immersion of explants into 70% ethanol for 45 sec followed by 0.8% sodium hypochlorite for 5 min. Cultivated anthers developed 50 and 70% of calli with 0.1 mg L<sup>-1</sup> indole-3-acetic acid (IAA)+5 mg L<sup>-1</sup> kinetin (KIN) and 0.1 mg L<sup>-1</sup> indole-3-acetic acid (IAA)+10 mg L<sup>-1</sup> kinetin (KIN), respectively. The calli oxidation increased in treatments free of activated charcoal, daily pre-refrigeration (4°C for 48 h) and 20 mg L<sup>-1</sup> of kinetin (KIN). The best plant growth regulator concentration for stimulating calli formation was 5 mg L<sup>-1</sup> of kinetin (KIN).
[show abstract][hide abstract] ABSTRACT: The tomato cv. ‘Santa Clara’ is widely cultivated among tomato producers in most of the South-east of Brazil. Recently, some plants of this cultivar were identified with morphological alterations in both vegetative and reproductive organs. These plants showed firm (firme) ripe fruits, slow and delayed ripening. They also had yellow leaves associated with precocious senescence and flowers with pale stigmas. The objective of this work was to determine the genetic model of inheritance for this mutation and to evaluate its effects on shelf life and loss of firmness in mature fruits, as well as analyse the occurrence of genetic relationships between this putative mutant and other pleiotropic mutants. Mutated plants were crossed with the non-mutant cv. ‘Santa Clara’ and some previously described pleiotropic mutants. Seeds of F1 and F2 generations and backcrosses were obtained for the segregation analysis. Morphological characteristics modified by this mutation are governed by a recessive gene with pleiotropic effects. In addition, the test of allelism showed a lack of genetic complementation between the ‘firme’ mutant and lutescent-2 mapped on chromosome 10. Fruits of the ‘firme’ mutant had a slower rate of softening compared with the cv. ‘Santa Clara’ and its hybrids. The fruit shelf life of the mutant ‘firme’ was significantly superior to the other genotypes. No maternal effect was detected in either qualitative or quantitative characteristics. Based on the data, the mutation ‘firme’ in the cv. ‘Santa Clara’ is located in the region containing the l-2 locus, which promoted alterations in ripening and post-harvest physiology of fruits. The mutation ‘firme’ may represent a new allele of the gene lutescent-2 or a gene linked to physiological events of fruit ripening.
[show abstract][hide abstract] ABSTRACT: This study aimed to establish a protocol for the micropropagation of the cubiu ( Solanum sessiliflorum ) varieties Santa Luzia (SL) and Thaís (TH). Firstly, nodal segments were cultured onto MS-based medium supplemented with vitamins, mio-inositol (200 mg L<sup>-1</sup>), glycine (400 mg L<sup>-1</sup>), sucrose (30 g L<sup>-1</sup>) and agar (6.5 g L<sup>-1</sup>), plus NAA (0, 0.25 and 0.5 mg L<sup>-1</sup>) and BAP (0, 1.0, 2.0 and 3.0 mg L<sup>-1</sup>). In the second experiment, nodal segments were placed on MS medium, plus vitamins, sucrose (15 g L<sup>-1</sup>), agar (6.5 g L<sup>-1</sup>) and IAA (0 and 0.01 mg L<sup>-1</sup>) in combination with KIN, TDZ or ZEA at 0, 0.64, 1.25, 2.50, 5.0, 10.0 and 20.0 mg L<sup>-1</sup>. The combinations of NAA and BAP inhibited shoot-bud growth and maintenance of the apical dominance. High TDZ concentrations induced prolific shoot formation with the greatest number of axillary shoots, although with indefinite morphology in many cases. The combination of 0.01 mg L<sup>-1</sup> IAA and 5.0 mg L<sup>-1</sup> TDZ induced the most intense axillary shoot proliferation in SL, whereas 2.5 mg L<sup>-1</sup> TDZ and 0.01 mg L<sup>-1</sup> IAA, combined with 1.25 mL<sup>-1</sup> TDZ, were most effective for adventitious shoot-bud differentiation. For TH, the proliferation of axillary and adventitious buds was improved in the treatment with 5.0 mg L<sup>-1</sup> TDZ and 2.5 mg L<sup>-1</sup> TDZ, respectively. After 60 days of cultivation, the adventitious and axillary shoot-buds on MS-based medium lacking growth regulators were 4.2±0.32 cm long and the plants presented a well-developed root system.
[show abstract][hide abstract] ABSTRACT: Total fresh and dry weight of Capsicum chinense fruit accessions were inversely correlated with accumulation of dry matter, and fruits with a higher percentage of dry matter accumulated proportionally more total soluble solids. Based on regression analysis, a 1% increase in fruit dry weight was associated with a 0.28% improvement in total soluble content, up to a maximum total soluble solid content of 10.25%. Regardless of shape, larger fruits had thicker pericarps, and were therefore more suitable for open air fresh markets. Smaller fruits had thinner pericarps and higher concentrations of total soluble solids and were more appropriate for dehydration and paprika production. Dry fruits with color intensities greater than 200 ASTA units, as required for paprika production, were found in 18.4% of the analyzed accessions. A large number of accessions, close to 27%, had total capsaicinoid concentrations less than or equal to 1.9 mg g−1 dry weight, and can be considered as sweet or light pungent fruits. A small percentage of accessions (2.5%) were classified as extremely hot fruits.