Resumo em Inglês:

Abstract Macadamia is a nut tree native to Australian rainforest. Due to the small wild populations and the economic interest, studies assessing genetic information are fundamental for use and conservation of this species. Therefore, the present study aimed to assess the structure and genetic diversity of 28 cultivars of macadamia originated from United States, Australia and Brazil, introduced or developed by the Agronomic Institute’s breeding program, using 29 new microsatellite loci. The microsatellite loci showed high genetic diversity (3.65 alleles per locus on average). Our results also suggested the existence of no genetic structure between cultivars, regardless of their geographic origin. The modified Rogers’ distances between cultivars ranged from 0.227 to 0.671. Despite the lack of information about genealogy, the cultivars from this Brazilian germplasm showed moderate genetic diversity, so they can be used as parents in future crosses.

Resumo em Inglês:

Abstract The objective of this study was to evaluate the performance of hybrids and the heterosis in crosses of sweet sorghum using juicy sweet male-sterile lines and fertility-restoring lines with and without sensitivity to photoperiod. Thirty hybrids and six controls were evaluated in experiments laid out in a 6 × 6 triple lattice design. The genotypes differed for all traits. The general combining ability (GCA) of the R lines affected all traits, while the GCA of the A lines only affected juice extraction, total soluble solids, and tons of Brix per hectare (TBH). The photosensitive-restoring line CMSXS5022 had the highest positive GCA estimates for the fresh mass production and TBH traits. Heterosis was significant only for days to flowering and plant height. Overall, the photoperiod-sensitive hybrids stood out. The development of male-sterile lines requires better complementarity from restoring lines to reap the benefits of heterosis.

Resumo em Inglês:

Abstract Common bacterial blight (CBB) is an important disease in Phaseolus vulgaris L. A carioca diversity panel (CDP) composed of 149 cultivars of common bean was genotyped with 1,616 SNPs and evaluated for Xanthomonas phaseoli pv. phaseoli (Xap) resistance aiming to identify QTLs. Phenotypic evaluation was done in controlled conditions. The plants displayed in a randomized block design, with 3 replications were evaluated ten days after inoculation. GWAS analysis using the BLINK model identified one SNP on chromosome Pv07, with a different genomic location in relation to previous studies. Considering a confidence interval of 100 kb, gene annotation identified 13 candidate genes related to defense-associated genes, and their key functional motives were discussed. The marker identified may constitute an important resource for future marker assisted CBB resistance breeding.

Resumo em Inglês:

Abstract Genetic selection efficiency is measured by accuracy. Model selection relies on hypothesis testing with effectiveness given by statistical significance (p-value). Estimates of selection accuracy are based on variance parameters and precision. Model selection considers the amount of genetic variability and significance of effects. Questions arise as to which one to use: accuracy or p-value? We show there is a link between the two and both may be used. We derive equations for accuracy in multi-environment trials and determine numbers of repetitions and environments to reach accuracy. We propose a new methodology for accuracy classification based on p-values. This enables a better understanding of the level of accuracy being accepted when certain p-value is used. Accuracy of 90% is associated with p-value of 2%. Use of p-values up to 20% (accuracies above 50%) are acceptable to verify significance of genetic effects. Sample sizes for desired p-values are found via accuracy values.

Resumo em Inglês:

Abstract Searching for new approaches to confer resistance to diseases in plants is one of the main objectives of the Cacao breeding program (CBP). Witches' broom (WB) and black pod rot (BPR) are important cacao diseases in Bahia, Brazil. This study aimed to evaluate the resistance in plants from 40 progenies of genetic crosses between elite clones to natural infection by high levels of Moniliophthora perniciosa and Phytophthora spp. WB and BPR infection assessments were conducted in the field, including evaluation of vegetative brooms (VB), cushion brooms (CB), and total brooms (TB), as well as the percentage of WB-diseased (FRUWB) and BPR-diseased (FRUBPR) fruits. Ten progenies showed resistance to infection in both the canopy and fruits. No significant differences between the progenies were detected for FRUBPR.

Resumo em Inglês:

Abstract Bayesian approaches applied in association studies select regions of single-nucleotide polymorphisms, indicating genes with important effects. The Bayesian methods differ in terms of the distribution assumed for the marker effects. Here, we used the window posterior probability of association to detect potential regions. The present study evaluated the efficiency of these methods in identifying regions located close to genes. Data were simulated in six scenarios. Considering the lack of dominance, BayesA was more efficient in the scenario with three QTLs. For scenarios with 10 or 100 QTLs, BayesCπ and BayesDπ were more efficient according to the false positive rate and detection power. Considering the presence of dominance, all methods were similar in the scenario with three QTLs, except in terms of accuracy. BayesDπ was superior in the scenario with 10 QTLs, while BRR was more efficient in the scenario with 100 QTLs.

Resumo em Inglês:

Abstract Topcrosses are routinely used in maize-hybrid programs. This study aimed to evaluate heterosis components and combining ability to predict hybrid means between synthetics from two groups of S1 maize lines using the intergroup topcrosses model that includes S2 lines. Two groups, each with 30 S1 maize lines, were crossed using an intergroup topcross system, with a mixture of lines from one group as a tester for the contrasting group. Simultaneously, 30 S2 lines from each group were generated via self-pollination. Lines and topcrosses were experimentally evaluated and the data were analyzed using a model adapted to the study design. The results showed the suitability of the proposed model for studying heterosis components and general combining ability, detailing additive and dominance effects. Prediction of hybrid means between synthetics showed the potential of the lines to generate base populations for an interpopulation breeding program.

Resumo em Inglês:

Abstract ‘IAC Sempre Verde’ is a medium-seeded runner-type peanut highly resistant to late leaf spot and rust, the main diseases in peanut cultivation in Brazil. The newly released cultivar showed remarkable yield advantage over controls when diseases were not controlled and represents the first possibility for peanut cultivation under “Organic” management.

Resumo em Inglês:

Abstract BRS A502 is an upland rice cultivar with a medium cycle, high resistance to lodging, superior yield potential and grains of excellent industrial and cooking quality. The cultivar is indicated for crop rotation and succession in areas under intensive agriculture in the main field crop regions of Brazil.

Resumo em Inglês:

Abstract MGS Guaiçara e MGS Vereda are resistant to Meloidogyne paranaensis, one of the most aggressive nematode parasites of coffee. MGS Vereda is an early maturation cultivar, whereas MGS Guaiçara has a medium maturation cycle. Both cultivars produce red fruit, have high size, and high yield potential in infested areas.

Resumo em Inglês:

Abstract BRS Pampa CL is a rice cultivar developed by Embrapa, recommended for irrigated cultivation in Rio Grande do Sul State, Brazil. It shows modern architecture, high tiller ing, early cycle, and tolerance to the imidazolinone herbicide Kifix®. It stands out for its high yield potential and excellent grain quality.

Resumo em Inglês:

Abstract Cultivar BRS A706 CL is a new rice cultivar, resistant to herbicides of the chemical group of imidazolinones, with a yield potential of 15,635 kg ha-1. It has intermediate maturation, lodging tolerance, the stay green trait, moderate rice blast resistance, a high milling yield and premium grain quality.